# User:Cmglee

Hello world!

My interest in editing Wikipedia is in illustration, so let me know if you wish some article on science, technology, architecture or mathematics illustrated.

Here is some of my work to date:

$\begin{array}{l} \text{mean} \\ = e^{\mu + \sigma^2 / 2} \\ = e^{0 + 0.25^2 / 2} \\ \approx 1.032 \\ \text{mode} \\ = e^{\mu - \sigma^2} \\ \approx 0.939 \\ \end{array}$

Distances of selected bodies of the Solar System from the Sun. The left and right edges of each bar correspond to the perihelion and aphelion of the body, respectively. Long bars denote high orbital eccentricity. The radius of the Sun is 0.7 million km, and the radius of Jupiter (the largest planet) is 0.07 million km, both too small to resolve on this image.

Left frame
Drawings and
3D renders
Photographs Maths and tables Charts using
EasyTimeline
Templates for
general use

...plus selected pieces of interest...

## comparison optical telescope primary mirrors.svg ☎ 7 Jul 2014

Comparison of nominal sizes of primary mirrors of some notable optical telescopes (click for detail)

I had been reading about the Very Large Telescope, European Extremely Large Telescope and Overwhelmingly Large Telescope (when will they run out of adverbs?!) but couldn't picture how much larger each progressively gets, so I drew this graphic comparing the nominal sizes of the primary mirrors of some large existing and future optical telescopes with various objects like tennis and basketball courts, and the Arecibo radio telescope.

The telescopes are colour-coded by country in which they are located, and whether they currently exist. Their dimensions are as found on the Web, though holes in most mirrors are not shown due to insufficient data. Dotted circles show mirrors with equivalent light-gathering ability.

I'm amazed how enormous the cancelled Overwhelmingly Large Telescope would have been, and conversely, how relatively small the space telescopes (even the JWST). Also note that the hole in the E-ELT is as big as the entire mirror of the largest current telescopes!

SVG-wise, this is my first time using CSS in an original SVG. Quite a neat idea — I must do it more often...

Very nice picture! But I notice that the segmented mirrors show the central aperture, while all the circular mirrors are shown as solid The LSST, for example, has an extremely large central aperture (5116 mm hole in 8360 mm outer diameter), which greatly reduces its collecting area. Likewise, OWL had a very large (33m) central aperture due to the decision to use a flat secondary. Would you like a list of sizes for the various telescopes? 71.41.210.146 (talk) 01:12, 10 July 2014 (UTC)

## Titanic casualties.svg ☎ 14 Jun 2014

Breakdown of survivors and victims of the RMS Titanic (click for more detail)
Visualisation of some British currency terms before decimalisation (click for more detail)

I recently decided to explore a sometimes-derided type of statistical chart: Pictograms.

Often considered eye-candy, particularly when used where a bar chart is more appropriate, pictograms are usually relegated to infographics in mass media.

I wondered in which use cases pictograms were superior. One example I could think of was where the reader might want to count the number of icons, instead of looking up a scale. This fits well with small discrete numbers, especially where each icon naturally represents a single unit.

To that end, I drew these pictograms, which I think gives a better picture (mind the pun!) of the subject than any other type of chart. Any thoughts?

## Fourier series square wave circles animation.gif ☎ 4 May 2014

This video has an excellent visualisation of the effect of taking progressively more terms in a Fourier series. I wish I had seen it when I was learning about Fourier transforms etc, and so, to help future students, I decided to compare four functions using the same technique:

The animations were made by first creating SVGs of their 60 frames and uploading them to Wikimedia Commons to render them into PNGs, which unfortunately centre-aligned the first tspan (instead of the entire row) of each denominator. They were then downloaded, and sliced and combined into GIF animations with these ImageMagick commands:

convert.exe Fourier_series_square_wave_circle_animation.svg.png -crop 1x60@ +repage +adjoin Fourier_series_square_wave_circle_animation_%%03d.png
convert.exe -delay 10 -loop 0 -page +0+0 ^
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-coalesce -depth 3 -colors 32 -dither FloydSteinberg Fourier_series_square_wave_circle_animation.gif


## Nucleosynthesis periodic table.svg ☎ 31 Mar 2014

Periodic table showing the origin of elements

As Neil deGrasse Tyson movingly put it [1], an astounding fact is that we are star dust — most of the elements in our bodies (barring some recent radioactive-decay products) were created in stars, by cosmic rays or during the Big Bang itself.

At a talk at the Cambridge Institute of Astronomy, the speaker presented a slide similar to this periodic table showing the origins of the elements. I was surprised to find Wikipedia without an equivalent graphic, so decided to make one!

Simplified Git data flow

The SVG itself is straightforward, the only interesting bit being the Appley skeuomorphic gradient shading I "invented" when making the Git chart on the left:

  

Applying this to a shape makes its top 10% half-transparent white, and its bottom 10% black but fully transparent. The middle region has a curious gradient which, in my opinion, looks quite attractive when overlaid on a copy of the shape filled with the intended solid colour.

## Comparison ISS HST orbits globe centered in Cape Verde.svg ☎ 28 Feb 2014

Comparison of ISS and Hubble Space Telescope orbits

I caught Gravity on a flight and marvelled at the amazing special effects and way-above-average accuracy of its portrayal of space travel, particularly how the alarm sounds came back when the hallucination turned up the air pressure and how the Soyuz righted itself during reentry.

Nevertheless, one of the popular gripes is how easy it was to travel between the Hubble, ISS and Tiangong. Of course, one could imagine an alternate universe where they are put into almost identical orbits. When the film first came out, I drew this graphic to show how different the real ISS and Hubble's orbits are. Even if they were at the same height and almost the same longitude/latitude, their orbital inclinations would require huge change in delta-v which I doubt a backpack could provide.

As for the creation of the image, I faced the classic problem of "drawing Saturn with its rings": How to draw a circle with an ellipse both behind and in front of it?

The solution I used was to erase half the ellipse using an SVG clip-mask, and draw it over the globe which already has the full ellipse drawn under it. Because of anti-aliasing, the twice-drawn half is slightly thicker than the other half, but it's not noticeable at normal resolutions. I could have made the ellipse below also a half-ellipse but thought that any gap in the joint would look even worse...

## Burj Khalifa floors.svg ☎ 14 Jan 2014

Burj Khalifa with floors colour-coded by function

This dimetric projection of the tallest building in the world is my first SVG animated using CSS3. I had previously used JavaScript/ECMAScript to animate SVG but the Wikimedia uploader rejected it as JavaScript was considered a security risk. Using CSS3 is more limited, allowing noninteractive animation of various attributes, the transform attribute in this case.

Using the technique to simulate 3D rotation below, I rotated each different floor plan, replicated it in the appropriate colour as many times as needed, and scaled the whole group vertically by half. The illusion was reinforced by the sheer number of floors. The only niggles were...

1. The framerate of the animation: each floor being made of 12 elements (6 for each fill and stroke — combining both resulted in an ugly redundant line at the apex of each lobe) and there being over 200 floors meant that there were over 1200 elements to animate in each frame,
2. The sharp angles of the base and spire "floors" giving a jagged appearance in silhouette, and
3. The Mediawiki renderer ignoring the CSS3 — it would have been perfect if it rendered an animated GIF (animated PNGs being less well-supported).
Firefox 26.0 breaks animation

I was so satisfied that I retroactively applied it to the Absolute World Tower model and was even more impressed with the quality of the rendering. As there were fewer elements and the floors were more rounded, both the animation and the silhouette were much smoother. That the Mediawiki renderer ignores CSS3 was used to show the rightmost text label only in a static thumbnail.

Sadly, browser support for CSS3 is still patchy: the test animation of falling snowflakes works in Chrome, but not in Firefox 26.0. At time of writing, noone has suggested a fix or workaround for this bug :-(

Incidentally, it's now been 2 years since I started this behind-the-scene look at my work with Wikipedia/Wikimedia. Does anyone actually look at this? If so, I'd love to hear from you — cheers!

## coupon collector problem.svg ☎ 28 Dec 2013

Graph of number of coupons, n vs the expected number of tries needed to collect them all, E (T )

I play a game which has characters making various sculptures, each attempt generating 1 of 12 possible sculptures at random. Every time I complete a "collection" of 12, I get a bonus and get to start a new collection.

I wondered how many tries I need, on average, to complete a collection from scratch. A search introduced me to the Coupon collector's problem. Paraphrasing the article,

In probability theory, the coupon collector's problem describes the "collect all coupons and win" contests. ... Given n coupons, how many coupons, E (T ) do you expect you need to draw with replacement before having drawn each coupon at least once?

Hn = 1/1 + 1/2 + 1/3 + 1/4 + 1/5 + ... + 1/n

Mathematical induction gives E (T ) = n Hn , which I've plotted for n from 1 to 60 (to cover the case of 52 playing cards — I'd have preferred 100, but that makes the smaller bars too hard to see).

I added dotted lines to show the number of tries needed for each coupon. Though this value increases, it increases rather slowly, as E (T ) being linearly proportional to n logn implies.

Back to my game, my 12 sculptures would thus require 38 attempts, on average. In practice, I found that it takes fewer tries, perhaps because it wasn't as random as I'd thought.

By the way, I love the elegant proof that the harmonic series diverges (goes to infinity as n approaches infinity), unlike a geometric series with a ratio between -1 and 1 (not inclusive). I'll consider drawing a proof without words of it one day...

## rolling shutter effect.svg ☎ 10 Nov 2013

Simulated effect of a rolling shutter on a spinning disc (Click for animation)
My, what flexible rotors you have!

I used to be baffled by photographs like the one of the helicopter on the left, wondering what on Earth could have caused such distortion on the blades! I recently learnt that it is an effect of the rolling shutter on many digital cameras, especially those on mobile phones.

Unlike film cameras which expose the entire frame at the same time (actually they have rolling blinds too, but the effect is only apparent at very fast shutter speeds), cameras without a mechanical shutter expose and read off a line at a time. This means that by the time the last row is captured, a fast-moving subject will have moved significantly from where it was when the first row was captured.

To illustrate the warping more precisely, I came up with a sequence of 24 frames of a rotating disc and simulated a rolling shutter scanning a row at a time. In each frame, the left half shows the state of the disc and the position of the captured row, while the right half shows the image captured until that point. Sadly, there is a bug in Mediawiki (not in Firefox or Chrome) that renders some artifacts in the top rows; I guess it didn't like my 24 levels of nesting to generate the captured image sequence, the most I've used to date.

Nevertheless, it's now clear to me that the part of the disc moving in the direction of the scan (the right side) is smeared out into large shapes while those moving the other way (the left side) is compressed. The small number of rows cause the jagged appearance; more rows in a real camera lead to smoother curves.

To complete the simulation, I sliced the image into 24 layers in Gimp and stitched them into GIF animation.

I later found this video which explains it even better. I might make a similar animation in the future...

UPDATE 31 MAR 2014: Really proud to see my animation not only used on Vsauce, but host Michael Stevens even built on it to explain that our view of the Andromeda Galaxy suffers from a rolling-shutter effect.

## Hipparcos Catalogue equirectangular plot.svg ☎ 21 Oct 2013

File:Hipparcos_Catalogue_equirectangular_plot.svg marked the completion of my trio of charts of objects in the night sky, all of right ascension against declination in an equirectangular grid:

 The first plot is of the 88 modern constellations. Surprisingly, constellations are now defined as regions of the sky rather than groups of stars, so the graphic shows their boundaries rather than the traditional lines-between-stars. I also added the ecliptic and a negative bitmap to show the Milky Way. User:Timwi kindly helped me shade the regions using the four-colour theorem, which help tell adjacent ones apart. The next graphic is of the fuzzy things catalogued in the 18th century by astronomer Charles Messier. As science progressed, it was discovered that they were very different objects, some being clouds of gas while others being clusters of stars. Yet others were whole galaxies far, far away... (but that was a long time ago!) The finale is a chart of the 2000 or so brightest stars more recently catalogued by the Hipparcos project. That was an opportunity to revive the lines-between-the-stars, which was obtained from data files of the excellent virtual planetarium, Stellarium. I'm tempted to draw them on the first plot, too, but that will have to wait for another day...

## cmglee London FCO Grand Staircase.jpg ☎ 28 Sep 2013

The Grand Staircase of the Foreign and Commonwealth Office

Another year, another Open House London!

This time, I managed to win the ballot for a place on the Arriva Heritage Bus Tour, which used the last classic Routemaster, RM2217 to take us to 5 landmarks:

I also visited the Foreign and Commonwealth Office (FCO), and the Brunel Museum and its recently-reopened entrance shaft of the Thames Tunnel.

Of course, my trusty camera came along, so here's another batch of photos for your viewing pleasure...

## million award logo.svg ☎ 27 Aug 2013

Logo for Million Award
 This user has not won a Million Award but is nevertheless proud to have designed a logo for it!

Today, I got my first Wikimedia request for a logo design (a very old hobby) for the so-called Million Award, which I think is a good idea — much as I enjoy drawing pretty pictures of my interests, I've long thought that my efforts benefit society most when spent on popular topics which are somehow lacking.

The requester, User:Khazar2 had adapted my visualization of 1 million graphic (see below), so I continued in that direction. Befitting the theme of "million", the middle cube has 1 millionth the virtual volume of the large cube, while the CMYK colours evoke the idea of "articles" in the traditional printing sense. "1M" is hopefully language-independent and the star is a common motif for awards such as the Barnstar.

The skewed text is also my first use of SVG matrix affine transformation, and I was delighted that the bottom-right edge of the star (simply Unicode character U+272A) lined up with the bottom-right side of the cube. It was also my first attempt to specify a particular font, in this case, one with tapering (not slab) serifs so that the "1" and "M" look more elegant and reminiscent of printed text.

All in all, it was a fun little project for the day!

## cmglee Horniman London skyline.jpg ☎ 25 Jul 2013

I revisited the Horniman Museum, one of my favourite museums in London because of their approach to education by comparing artifacts from different cultures. I also love their skeleton-skin preparations, which show just the skeleton in half of a stuffed animal, as it shows how the bones (and consequently, muscles and internal organs) fit in the body. These are some examples:

I also reshot the London skyline from Forest Hill to show a completed Shard. Sadly, the summer air was quite hazy, but some image-processing helped. In the style of Horniman, see how the city has changed in 1½ years!

London skyline from Forest Hill in July 2013
London skyline from Forest Hill in Jan 2012

## Template:Alcohol metabolism formulae ☎ 25 Jun 2013

A CrossCountry train passing behind the new building of the Laboratory of Molecular Biology in the Cambridge Biomedical Campus, view from the southwest on the Cambridgeshire Guided Busway bridge on 22 June 2013.

The Laboratory of Molecular Biology opened its doors to the public on Sat, 22 June, so my friends and I attended some talks, exhibitions and a tour of their new home. (I also used the opportunity to take some photos!)

One of the speakers talked about a mutation causing possibly the greatest cancer risk in the world: ALDH2*2

With China rapidly adopting a drinking culture, about 25% of the East Asians (perhaps 300 million people) face increased risk of esophageal cancer. If I understood correctly, the risk of an affected person drinking, compared to an unaffected one, is greater than that of lung cancer from smoking (of course, the quantity matters...)

I couldn't find a graphic of the breakdown of alcohol in the alcohol flush reaction page, so tried to create one. I could have done it in SVG, but thought it was an interesting experiment to do it in the LATEX-like maths "equation editor". I had to tweak the spacing quite a bit and couldn't draw diagonal double bonds, but managed the following:

$\begin{smallmatrix} &\text{H}& &\text{H}& & & &\text{H}& &\text{H}& & &\text{H}& & & \\ & | & & | & &\mathsf{ADH} & & | & & | &\mathsf{ALDH} & & | & & & \\ \text{H}\,-\!&\text{C}&\!-\!&\text{C}&\!-\,\text{O}\,-\,\text{H}&\xrightarrow{\qquad}&\text{H}\,-\!&\text{C}&\!-\!&\text{C}&\xrightarrow{\qquad\ }&\text{H}\,-\!&\text{C}&\!-\!&\text{C}&\!-\,\text{O}\,-\,\text{H}\\ & | & & | & & & & | & & \| & & & | & & \| & \\ &\text{H}& &\text{H}& & & &\text{H}& &\text{O}& & &\text{H}& &\text{O}& \\ \end{smallmatrix}$
Metabolism of alcohol (ethanol) to acetaldehyde (ethanal) and then acetic acid (ethanoic acid)

Whatjsay? :-)

## perpetual calendar cycle.svg ☎ 14 Jun 2013

Table showing the 400-year cycle of the 14 possible calendars in the Gregorian calendar, arranged in columns to show a semi-regular 28-year pattern. The days of week denote the day of week that January 1st of the numbered year falls on. "+" and darkened cells indicate leap years.

Timwi's image at http://imgur.com/gallery/eUMMCtb got me interested in calendars again — I must be getting old!

His most amazing find was that the 400-year cycle of the Gregorian calendar (the one in everyday use today) has a multiple of 7 days, meaning that the cycle repeats exactly every 400 years. But interesting and colourful as his graphic was, it didn't help with my understanding of how the 14 possible calendars actually change, so I decided to draw my own...

While on holiday, I wrote a quick program to output into a simple text file as one line separated by spaces:

• The day-of-week of January 1st of each year from 2001 to 2400 (unlike Timwi's choice of 2000 to 2399, I started with 2001 so that the rare 400-year leap on 29 Feb 2000 after 1 Jan wouldn't disrupt the pattern), and
• Whether the year was a leap year.

Changing the width of my text editor window let me see in how many years the pattern more-or-less repeated.

The answer was 28, not surprisingly the lowest common multiple of 7 (days in a week) and 4 (almost every 4th year is leap), the pattern disrupted only by the non-leap years 2100, 2200 and 2300. 28 columns would, however, be too wide, so I decided to go down then across, instead of across then down.

The pattern appeared more regular now, but the non-leap century years still played havoc, until I got the idea of skipping the necessary number of cells until the pattern resumed. There are actually 2 possible places each non-leap century year can go. I chose the later one so that 2300 doesn't end up at the top of its column.

This resulted in the graphic on the right. It's now much clearer to me how the calendars cycle — one day forward each non-leap year, and two days forward each leap year, except for the non-leap century years which leave large gaps.

P.S. I redrew the graphic in Wikitext below, if anyone wants an HTML copy.

Day of week of Jan 1 Leap year Gregorian calendar for years from 2001 to 2400
Monday   2001 2029 2057 2085 2125 2153 2181 2221 2249 2277 2317 2345 2373
Tuesday   2002 2030 2058 2086 2126 2154 2182 2222 2250 2278 2318 2346 2374
Wednesday   2003 2031 2059 2087 2127 2155 2183 2200 2223 2251 2279 2319 2347 2375
Thursday 2004 2032 2060 2088 2128 2156 2184 2224 2252 2280 2320 2348 2376
Saturday   2005 2033 2061 2089 2101 2129 2157 2185 2225 2253 2281 2321 2349 2377
Sunday   2006 2034 2062 2090 2102 2130 2158 2186 2226 2254 2282 2322 2350 2378
Monday   2007 2035 2063 2091 2103 2131 2159 2187 2227 2255 2283 2300 2323 2351 2379
Tuesday 2008 2036 2064 2092 2104 2132 2160 2188 2228 2256 2284 2324 2352 2380
Thursday   2009 2037 2065 2093 2105 2133 2161 2189 2201 2229 2257 2285 2325 2353 2381
Friday   2010 2038 2066 2094 2106 2134 2162 2190 2202 2230 2258 2286 2326 2354 2382
Saturday   2011 2039 2067 2095 2107 2135 2163 2191 2203 2231 2259 2287 2327 2355 2383
Sunday 2012 2040 2068 2096 2108 2136 2164 2192 2204 2232 2260 2288 2328 2356 2384
Tuesday   2013 2041 2069 2097 2109 2137 2165 2193 2205 2233 2261 2289 2301 2329 2357 2385
Wednesday   2014 2042 2070 2098 2110 2138 2166 2194 2206 2234 2262 2290 2302 2330 2358 2386
Thursday   2015 2043 2071 2099 2111 2139 2167 2195 2207 2235 2263 2291 2303 2331 2359 2387
Friday 2016 2044 2072 2112 2140 2168 2196 2208 2236 2264 2292 2304 2332 2360 2388
Sunday   2017 2045 2073 2113 2141 2169 2197 2209 2237 2265 2293 2305 2333 2361 2389
Monday   2018 2046 2074 2114 2142 2170 2198 2210 2238 2266 2294 2306 2334 2362 2390
Tuesday   2019 2047 2075 2115 2143 2171 2199 2211 2239 2267 2295 2307 2335 2363 2391
Wednesday 2020 2048 2076 2116 2144 2172 2212 2240 2268 2296 2308 2336 2364 2392
Friday   2021 2049 2077 2117 2145 2173 2213 2241 2269 2297 2309 2337 2365 2393
Saturday   2022 2050 2078 2118 2146 2174 2214 2242 2270 2298 2310 2338 2366 2394
Sunday   2023 2051 2079 2119 2147 2175 2215 2243 2271 2299 2311 2339 2367 2395
Monday 2024 2052 2080 2120 2148 2176 2216 2244 2272 2312 2340 2368 2396
Wednesday   2025 2053 2081 2121 2149 2177 2217 2245 2273 2313 2341 2369 2397
Thursday   2026 2054 2082 2122 2150 2178 2218 2246 2274 2314 2342 2370 2398
Friday   2027 2055 2083 2100 2123 2151 2179 2219 2247 2275 2315 2343 2371 2399
Saturday 2028 2056 2084 2124 2152 2180 2220 2248 2276 2316 2344 2372 2400

## Dewan Rakyat 2013 Equal Area.svg ☎ 9 May 2013

Results of the Malaysian Dewan Rakyat based on the 2013 general election, showing parliamentary constituencies represented by equal-area hexagons with approximate geographic locations.

Once again, I'm honoured to see this cartogram of the parliamentary constituency results of the Malaysian general election, 2013 appearing on the main page of the Chinese Wikipedia.

To be honest, most of the credit should go to User:Hytar who made the cartogram for the Malaysian general election, 2008. I just fixed a few minor cosmetic issues, tidied up the SVG code and updated the data to reflect the 2013 results. Due to his or her judicious use of CSS, the task was pretty straightforward.

I must give kudos to Hytar, too, for being so supportive and polite — a model Wikipedian if there was one!

The next job is to update File:Dewan_Undangan_Negeri_2008_Equal_Area.svg with this year's results. Hytar referred to some spreadsheets going around. Obtaining one would make updating the 505 hexagons much easier.

## Template:Blakey 65moll.jpg K/T impact site ☎ 9 Apr 2013

* Impact site
* Impact site
* Impact site
K/T impact site on a contemporary world map (65 mya)[1]

Today, I discovered a new technique to annotate images, using the Annotated image template. I had previously converted bitmaps to Base64 and embedded them in SVG files. With the template, I could add labels to any image directly in the Wiki markup.

For example, the code below produces the graphic on the right. The template also let me crop the sides of the Mollweide projection, to make the graphic fit inside text and yet allow detail on the map to be clearly seen. To isolate the label from the bitmap, I repeated it twice in black with slight offsets to simulate an outline — an alternative was to use a CSS shadow but CSS support for it is dicey.

I was surprised to find plenty of maps of the Chicxulub crater, the location of the Cretaceous–Paleogene_extinction_event, but no world maps showing this location on Wikimedia. Of course, the world looked a bit different 65 million years ago!

{{ Annotated image
| image   = Blakey_65moll.jpg
| caption = K/T impact site on a contemporary world map (65 mya)<ref>[http://www.scotese.com/K/t.htm K/T extinction]</ref>
| width   = 300 | height = 190 | image-width = 400 | image-left = -45 | image-top = -3
| annotations = {{Annotation|74|64|* Impact site|font-weight=bold|color=black}}
{{Annotation|76|66|* Impact site|font-weight=bold|color=black}}
{{Annotation|75|65|* Impact site|font-weight=bold|color=white}}
}}


## chain hoist.svg ☎ 10 Mar 2013

Example of a differential pulley

Tightening border security

Ever since I learnt about the differential pulley, I have been intrigued by the mechanism. Although it superficially resembles a block and tackle, at least two of its pulleys are sprockets, which engage with a chain, hence its other name, "chain hoist". Additionally, these two pulleys are joined together, and the ratio of their diameters (or radii) determines its mechanical advantage.

Drawing a graphic of it was an interesting exercise in SVG-hacking:

First, the teeth of the sprockets were simply the dotted stroke (outline) of the circle representing the pulley, set to the same colour as its fill, and with the duty cycle, phase and width adjusted to fit.

Next, I needed a path that looked like a chain, and found a way to do it with three dashed lines of different duty cycles, phases, widths and colours, one of them in the background colour to "erase" the hole in the links. This looked fine until I overlaid the chain on the pulleys, making the background colour incorrectly appear over the pulleys. If only clip paths had an inverse function which let one ignore pixels inside the path, rather than outside!

I left the problem for over a year before discovering masks. I could now draw the chain without the holes and overlay the whole thing on any background. The experiment on the left, a world map with borders replaced with chains, proved that this technique was feasible as long as turns were not too sharp. The hack was successfully applied to the differential pulley graphic (right), though I later found that Google Chrome had trouble with my mask. Oh well...

## commons:Category:Historical images of Penang ☎ 3 Mar 2013

Mount Erskine in 1824

I met User:Charles Matthews, User:Deryck Chan and User:Magnus Manske at the Cambridge Wikimedia Meetup Number 17 again yesterday and they convinced me that artwork from 1850 and before is globally considered public domain. I've therefore completed upload of 50 historical paintings and drawings of Penang housed in the Penang Museum and Art Gallery. The works show a much quieter island compared to the bustling city of today, but likely presents a European colonist's romanticised perspective. Nevertheless, it serves as a good historical record of the island.

There are 11 other pieces dating from after 1850, and 2 with dates unstated. Perhaps someone can upload them as they come out of copyright in the coming years...

## Sexagenary cycle years.svg ☎ 9 Feb 2013

Relationship between the current Sexagenary cycle and Common Era years
An optical illusion similar to Rotating Snakes by Kitaoka Akiyoshi

As several Asian cultures celebrate the lunar new year tomorrow, I made a couple of somewhat related illustrations.

I have sometimes wondered how the Chinese decide that a particular year is the Year of the Water Snake (for example). I knew that the 12 animals of the Chinese zodiac go in sequence but the element was a mystery. The Sexagenary cycle article makes it clear: The element cycles in the order wood, fire, earth, metal and water, changing every two years (the first year being yang and the second, yin). With that in mind, I drew the graphic on the right, adding in the numeric years. As it wasn't immediately obvious, I also added a tortuous line to show the progression — hope it's not too messy... I initially laid the years out in a table before realising that they wrap around in both X and Y axes: The surface of a toroid! Alas, drawing a toroidal surface isn't that easy, so the best I could manage was to make an annulus (mathematics) and wrapping the element radially.

The graphic on the left is based on a clever optical illusion which tricks the brain into seeing movement where there is none. The original, named Rotating Snakes, by psychologist Kitaoka Akiyoshi is an example of peripheral drift illusion which works on the viewer's peripheral vision. For best effect, one should use as large an image as possible, such as this one. An even more stunning illusion is found on the cover of the indie album Merriweather Post Pavilion.

Happy lunar new year to all who celebrate it!

## Comparison of pyramids.svg ☎ 31 Jan 2013

English version with collapsed pyramid at Meidum
German version with Bosnian "Pyramid of the Sun"

I've just updated my comparison of some pyramidal buildings, adding the collapsed pyramid at Meidum to replace the Bosnian "Pyramid of the Sun" which was forcefully removed due to the misconception that I had tried to promote the Bosnian hill as a building. That was never my intention — I thought that including it in the graphic only served to highlight how ridiculously enormous it was compared to other pyramids. Nevertheless, an editor removed it, leaving an unsightly gap in the labels.

Meanwhile, I had been thinking about including the Meidum pyramid but felt that my SVG skills were inadequate at the time. Now that I had more experience with Bézier curves and a gap to fill, I traced this illustration and added it to the graphic, renumbering the pyramids in the process (I had checked that no pages that used it referred to the numbers).

Guess you can't win every battle, but you can make the most of the outcome!

## Template:Distance from Sun using EasyTimeline ☎ 2 Jan 2013

Today marks the Perihelion of the Earth, the moment in a year that the Earth is closest to the Sun, paradoxically near the coldest time of year in the Northern Hemisphere!

A while back, I discovered the ability to render graphics in an article by just writing some code, instead of uploading an image (such as SVG) and transcluding it: EasyTimeline.

Originally designed to create timelines, it can be repurposed to draw bar charts in general. My first use of it is the chart below graphically illustrating the range of distances some bodies of the solar system can be from the Sun. It can be seen that the inner planets have almost circular orbits whereas the outer dwarf planets and Halley's Comet have very eccentric orbits.

Distances of selected bodies of the Solar System from the Sun. The left and right edges of each bar correspond to the perihelion and aphelion of the body, respectively. Long bars denote high orbital eccentricity. The radius of the Sun is 0.7 million km, and the radius of Jupiter (the largest planet) is 0.07 million km, both too small to resolve on this image.

## Mesoamerican Long Count Calendar visualization.svg ☎ 21 Dec 2012

Visualisation of the Mesoamerican Long Count calendar
Visualisation of powers of ten from 1 to 1 million

I'm pleasantly suprised at the lack of media coverage of the 2012 phenomenon, considering the frenzy when the 2012 movie was released — it's certainly nothing like what accompanied the Y2K scare.

Nevertheless, I was curious to find out the relevance of today's date in the Mayan calendar and read about their units of time. 21st December 2012 marks the end of the 13th (written 12 in their dates as they start counting at zero), and the start of the 14th b'ak'tun, a unit of time 144000 days long (around 400 years).

Using the idea I developed to visualise largish numbers at the same scale (one million in the illustration on the right, and one billion in this one for high-resolution screens), I drew similar blocks representing the Mesoamerican time units up to a piktun (around 8000 years), in principle representing almost 3 million small cubes in the largest block! I added colours and a scale showing equivalent dates on the Western calendar. To reduce the width of the image, I flipped my trimetric projection horizontally.

From this image, I can see that while the date is interesting, it's not exceptional as it occurs once every 394 years. Moreover, nothing major happened at the last few changeovers: 1618, 1224 and 830.

On that note, I'll just wish everyone, "Happy new b'ak'tun!"

## Heathrow Airport map with third runway.svg ☎ 17 Dec 2012

Map of London Heathrow Airport showing proposed extension and third runway
Fukushima I and II Nuclear Accidents Overview Map as of 15 March 2011

The map on the left is my first attempt to combine an SVG export of OpenStreetMap data with annotation to show the terminals of London Heathrow Airport and its proposed extension, although I had previously embedded bitmaps of OpenStreetMap maps in the illustration of the Fukushima Daiichi nuclear disaster (right).

Though I have used Heathrow Airport for many years, I had no idea about its layout, other than the Central Bus Station and Underground station serving Terminals 1 and 3 (and formerly Terminal 2) while Terminal 4 had its own stations. The map now makes it clear how the buildings are laid out with respect to the runways and one another. I took the opportunity to illustrate the controversial third runway and extension, which has garnered plenty of press coverage in the UK.

Technical-wise, I found adding annotations straightforward but modifying existing SVG objects (even just changing their colours) quite difficult, particularly since there were so many objects that I had to hunt down the target object by colour, which was specified as, for instance, rgb(80%,60%,100%) instead of the more common #cc99ff format. I also thought the SVG was extremely inefficient in terms of file size. I would have, for example, grouped all objects of the same style and applied the styling to the group, rather than style each object individually. If I ever need to annotate an exported OpenStreetMap SVG again, I'll consider using an editor like Inkscape.

## Parallax barrier vs lenticular screen.svg ☎ 30 Nov 2012

Comparison of parallax-barrier and lenticular autostereoscopic displays
Principle of operation of a pound lock

Another thing that we talked about at the CUWPS gathering was three-dimensional (3D) displays, such as those in the Nintendo 3DS. I showed the group the drawing on the left to illustrate the principle, and the subject changed to drawing SVG.

We looked at the source code and discussed use of groups, transforms and defined blocks to reduce the effort of producing one, while also saving on file size.

This drawing is one of my forays into simulating a 3D scene in a 2D medium, ironic considering the subject of the drawing is technology to simulate 3D with 2D!

The projection used is the approximate isometric projection used in isometric graphics in video games and pixel art, actually a dimetric projection. It simplifies mapping between 3D and 2D coordinates in this case, so I could work out the coordinates by hand, but traditionally, it allowed pixels to fall neatly into the raster graphics matrix without needing antialiasing. It looks slightly more aesthetic than true isometric to me, too, as more of the sides is visible than the top, just like how I would sketch a 3D object.

Another drawing done with the same projection is the sequence on the right is showing how some canal locks work.

## Penang Harbour HMS Magpie 1884 Penang map.jpg ☎ 26 Nov 2012

Detail of an 1884 map showing Penang Island and part of Province Wellesley
1799 map of early George Town, Penang

I have always been interested in the small island of Penang and was over the moon when I found this scan (left) of an ancient map dating from 1799. Though it was only 13 years since Penang's founding, the map had landmarks such as Fort Cornwallis, Penang Road and the grid of streets near Beach Street. It was fascinating that while land to the southeast had been reclaimed to build Weld Quay, land to the north had been lost to the sea, which may explain why the Esplanade was built.

It then occurred to me that Penang being a British colony meant that there must be extensive historical records of early Penang within a stone's throw at the Cambridge University Library. I found that very book from which the 1799 map came, and also a more recent map in the Map Room (right) — how Penang had grown in 85 years!

I spoke of my experience with the Cambridge University Wikipedia Society at their gathering yesterday and discussed with President Deryck about expanding GLAM to include the University Library archives. I know I'd certainly be interested in their ancient maps ୯ ͡°  ͜১͡° ੭

## Cambridge University colleges timeline.svg ☎ 29 Oct 2012

Timeline of the colleges of the University of Cambridge compared with some events in British history.

I attended the 16th Cambridge Wikimedia meetup and inaugural Cambridge University Wikipedia Society meeting yesterday and had the pleasure of meeting several enthusiastic Wikimedians/Wikipedians and learning about the projects and ideas of User:Charles Matthews and User:Magnus Manske. I'm looking forward to the planned collaboration with the University of Cambridge and local museums.

Speaking of Cambridge University, on the right is a chart I made a while ago to illustrate the complex history of the colleges of the University of Cambridge. It shows the years of formation of the colleges, when they changed their names, and most importantly, when they started admitting women (or men, in the case of Girton College and Hughes Hall). Obtaining all this data from disparate sources was quite a challenge, and I'm still missing one crucial date:

When St Edmund's College became mixed.

Repeated emails to various parties in the college were unanswered, so I've shaded the transition to the range of years this could have happened. Anyone got any idea?

UPDATE 28 NOV 2012: User:Deryck Chan managed to get a statement from St Edmund's Emeritus Fellow Dr Michael A Hoskin that he remembered it as 1969. Pending confirmation of historical records, I've tentatively indicated 1969 as the year St Edmund's became mixed.

UPDATE 17 DEC 2012: Thanks to the tireless effort by the St Edmund's College Combination Room Women’s Officer, Miss Maryam Farooq, the year women could be admitted to St Edmund's College, as postgrads, has been established to be 1965.

## Container City massing model.svg ☎ 28 Sep 2012

Container City II.
Illustration of the structure of Container City showing how the containers are stacked.
Interior of Studio 12 in Container City I.

Last weekend, hundreds of establishments in London welcomed visitors for Open House London, and so I took the opportunity to visit a pioneering work of shipping container architecture at Trinity Buoy Wharf: Container City.

The structure consists of two buildings named Container City I and Container City II, made out of 52 old 40-foot shipping containers. Even the lift shaft and stairwell are containers standing on end. I really like the balconies made from the containers' open doors, and the bright colours.

Unlike the exterior, its interior looks pretty much like ordinary flats except for the portholes and occasional glimpses of the exterior, and tall people may find the low ceiling claustrophobic! Being an open house, a studio was open to the public, though I cynically think it's just a ploy to get people to rent it :-)

To better understand its structure, I reused my patented (not!) trimetric projection to depict the containers, one layer at a time. The SVG code was wholly done in Notepad++, believe it or not, though the hardest part was finding out what colour each container was painted!

## Using watch and sun as compass.svg ☎ 24 Sep 2012

A method to identify north and south directions using the sun and a 12-hour analogue clock or watch set to the local time, 10:10 a.m. in this example.

Continuing the theme of clock faces, I recently found out about a method scouts and similar groups learn to locate north and south using the sun and an analogue clock or watch:

As the sun appears to complete one rotation around the sky in 24 hours while the hour hand of a 12-hour clock takes 12 hours, bisecting the angle lets one identify the cardinal directions.

Unfortunately, modern timekeeping complicates matters with time zones and daylight saving. Most countries (except perhaps China and Kiribati) have time zones roughly corresponding to the local time. Daylight saving normally move clocks forward by an hour.

Using this information, the more detailed description at Cardinal_direction#Watch_face and the infamous marketing time, I illustrated these four scenarios:

1. In the northern hemisphere, with daylight saving.
2. In the northern hemisphere, without daylight saving.
3. In the southern hemisphere, with daylight saving.
4. In the southern hemisphere, without daylight saving.

The SVG itself is rather straightforward, the only difficulty being calculating the rotational transforms. What I'm a little proud of, though, is the sun rendered with 8 quadratic Bezier curves and a radial gradient!

## Template:Comparison_four_face_clocks.jpg ☎ 25 Aug 2012

Comparison of some notable four-face clocks at the same scale.
 Top-left: Metropolitan Life Insurance Company Tower Bottom-left: Allen-Bradley Clock Tower (previous record holder) Middle: Abraj Al Bait Top-right: Big Ben clock tower Bottom-right: Kremlin Clock
The Abraj Al-Bait towers

I had read about the Abraj Al-Bait Towers (left) and was curious to know how large its new-world-record clock actually was. The statistics, such as its 46-metre-diameter clock faces don't really do it justice, so I decided to create a photomontage of notable four-face clocks and clock towers, all at the same scale.

I chose the Allan-Bradley (the previous record-holder), Big Ben clock tower and Met Life Tower clocks, and later added the Kremlin one, as I felt that they gave a fair representation of famous large four-face clocks.

Orthorectified negative (top) and positive (bottom) representations of the picture, partially obscured.

Next was sourcing photographs of these clocks. I used the crop tool in Photoshop to orthorectify them, so that they appear like they were taken head-on. This process was simplified by the fact that the faces were nearly two-dimensional and I could assume that they were circular. I had had recent practice orthorectifying images, such as one of The Great Picture on the left.

I then had to find a way to get all the images to the same scale. Using the more common "diameter of dial" was troublesome, as the extent of the dial varied from clock to clock. Instead, I used the published lengths of their minute hands as it is easy to measure and one of the longest measurements specified, to reduce uncertainties.

Composite the montage, write a caption, create a template to present it uniformly, and that was basically it...

Now one can see how enormous the new clock is; the entire Big Ben clock tower (to be named the Elizabeth Tower for the British Queen's 60th year at the throne) could fit in the Abraj Al-Bait spire, and if the new clock had numbers on the dial (it has ticks), each number would be almost as big as one Big Ben clock!

## Turning Torso structure.svg ☎ 19 Aug 2012

Simplified plan and massing model of Tower 1 of Absolute World residential condominium in Ontario.
Turning Torso by night.
Illustration of the general structure of the Turning Torso by Santiago Calatrava. (1) shows a typical floor plan, where the grey circle denotes the core and blue shapes denote the steel framework. (2) shows the way the nine segments fit around the core, and (3) is a dimetric projection of the tower.

I met an architect who is a fan of Santiago Calatrava and we started talking about his Turning Torso. I found it difficult to visualise its shape, especially because most photograph show only the view taken from the ground (far left).

A little Googling later uncovered plans at http://www.calatrava.info/imageViewer/turningtorso/stor_plan.gif and http://blogfiles7.naver.net/data19/2006/10/27/22/Turning_Torso_Plans-43rd_Floor_1-jinsub0707.jpg .

With a trick I learnt from Adobe Flash to simulate 3D shapes with 2D ones (rotate then scale horizonatally and vertically by different amounts, and rotate again if needed), I drew this illustration (near left). I can now see the building's shape much more clearly! By the way, guess what influenced the choice of colours...

UPDATE 10 MARCH 2013: The idea was reused for the illustration of Absolute World on the right.

## Comparison convolution correlation.svg ☎ 10 Jul 2012

One corner of a squircle (blue) compared with that of a rounded rectangle (red)
Visual comparison of convolution, cross-correlation and autocorrelation.

I had wondered how to draw the intersection of two SVG shapes, such as the purple areas in the image on the right. One simple method is to set the opacity of the upper (drawn later) shape between 0 and 1, to make it semitransparent. However, this also causes the non-overlapping area to be semi-transparent.

It occurred to me that I could draw that shape twice. Calling the shapes A and B, we can draw A and then B fully opaque, and finally draw a semitransparent version of A on top. The opaque A ensures that the non-overlapping areas remain opaque. In theory, this is slightly different from a single opaque A due to anti-aliasing at its edges, but I haven't found any problems in practice.

The same idea was used in the graphic comparing convolution and correlation functions on two signals. This image additionally uses a more advanced technique with clip paths to shade the common areas under the graphs, but a description of it will have to wait until another day...

## Template:CiviltàValleIndoMappa-en ☎ 28 Jun 2012

Location of Cmglee in the Indus Valley and extent of Indus Valley Civilization (green).

I've just discovered a way to embed the name of the current page in a transcluded template, using the {{PAGENAME}} system variable.

For example, the caption of the image on the right should read, "Location of Cmglee in the Indus Valley and extent of Indus Valley Civilization (green)." (unless someone has changed the template!)

Of course, that doesn't make much sense! That's because the name of this page is Cmglee (its full name being User:Cmglee).

When the CiviltàValleIndoMappa-en template is used in the articles for the cities labelled, such as Mohenjo-daro and Harappa, it does its magic. For instance, in the Mohenjo-daro article, the caption reads, "Location of Mohenjo-daro in the Indus Valley and extent of Indus Valley Civilization (green)."

This allows the same image with an appropriate caption to be placed in multiple articles without having to copy and paste the same wikitext and then amend the city name in all of these pages. Moreover, updating the template instantly updates all pages using it. Nice!

## 2012 Summer Olympics torch relay map.svg ☎ 14 Jun 2012

Simplified route of the 2012 Summer Olympics torch relay.
Illustration of use of cubic Bezier splines to smooth a polyline, The different colours indicate different curviness values (black lowest and red highest). Triangles and squares indicate control points for the Bezier spline of the corresponding colour.

One of the frustrating limitations of SVG is the lack of a feature to automatically draw a smooth curve through a set of points. Sure, one can draw Bézier curves and elliptical arcs between pairs of points, but the coordinates of control points or arc radii must be specified.

Based on an algorithm at Stack Overflow, I developed a Perl function to automatically calculate the control points of cubic Bezier splines to smooth a polyline.

Each point (except the end points) can take up to two curviness values which determine how curvy or straight the curve on each side of the point is. Zero curviness results in a simple polyline. Applied to individual points, this can be used to create sharp corners. Negative curviness is used to create loops. The test curves on the left illustrate its use.

One of the first applications of this function (adapted to gradually change the colour of the curve along its length) is the creation of the simplified torch relay route map to the right. The actual route is far more tortuous than this. To make it easy to trace at this scale, I just wanted the curve to smoothly pass through all the marked places. To make crossings clearer, the curviness of certain points were tweaked until visually acceptable.

Another application, which I shall use more often as the need arises, is the drawing of the smooth curve of many mathematical functions. Currently, I have to generate hundreds of points to get a reasonably smooth curve. With this function, far fewer points will be required.

## cmglee ArcelorMittal Orbit.jpg ☎ 7 Jun 2012

ArcelorMittal Orbit viewed from Stratford High Street (A118).

I was pleasantly surprised and honoured to see my photograph of ArcelorMittal Orbit appearing on the Wikipedia main page on 17 May.

It was almost an accident that I shot this photo. On that fateful day, I had taken a coach from Cambridge to London to catch a London Prepares test event at the Olympic Park. I had expected to alight at Stratford, as I had done several times before. I was aghast that National Express had changed the 010 coach schedule to bypass Stratford, forcing me to get off at Bow and walk back to Stratford.

I remembered a great view of the Olympic Stadium and Orbit visible from the flyover above the A118 roundabout — I had uploaded a much lower-quality version of the same scene from a coach to London a few months before, as can be seen from the file's history. So, I decided to climb it.

Though there were no signs forbidding pedestrian entry, the overpass was mighty hairy, with nary a footpath to avoid the fast-moving traffic. Nevertheless, I was rewarded with this magnificent view — if you could call the Orbit "magnificent" ;-)

And that's the story behind the picture... Keep tuning in for more behind-the-scenes!

## Comparison gender life expectancy CIA factbook.svg ☎ 26 May 2012

Comparison of male and female life expectancy at birth for countries and territories as defined in the 2011 CIA Factbook, with selected bubbles labelled. The dotted line corresponds to equal female and male life expectancy. The apparent 3D volumes of the bubbles are linearly proportional to their population, i.e. their radii are linearly proportional to the cube root of the population.
Earthquakes of moment magnitude 8.0 and greater since 1900. The apparent 3D volumes of the bubbles are linearly proportional to their respective fatalities.

This BBC News article reminded me of the graphic on the right, which I made to compare the life expectancies (at birth) of males and females in different countries. As is widely known, women generally outlive men, particularly in the Eastern European countries labelled. The BBC article discusses possible reasons for this. There is, however, a reversal of this trend in sub-Saharan Africa. It is even more extreme in Montserrat, where (if the figures are to be believed), men live a whole 3¾ years longer than women, on average.

I initially found it a challenge to depict the size of the countries' populations, ranging from about 5000 to almost 7 billion. I could have used a logarithmic scale, but decided to imagine the markers as 3-dimensional "bubbles" with volumes proportional to their population. That let me cover the 6 orders of magnitude with radii covering 2 orders of magnitude, so that if, for example, the smallest bubble were 1 pixel wide, the largest would be a manageable 100 pixels wide.

Additionally, the transparent bubbles let multiple bubbles overlap and still be visible. A small dot at their centres allow the reader to read off the life expectancies in years.

The same idea was reused for the graphic on the left, showing fatalities in earthquakes of magnitude 8 and greater since 1900.

## Comparison of highest mountains.svg ☎ 9 Apr 2012

Comparison of the heights of the Eight-thousanders, Seven Summits and Seven Second Summits

Mark I
Mark II
Diagram comparing the height of Burj Khalifa to other buildings and structures

A recent exchange I had with RacerX11 reminded me of the benefits of constructive cooperative editing.

I (and presumably some others) have wondered how the famous tall mountains around the world, such as Aconcagua and Kilimanjaro compare with the giants of the Himalayas. Of course, I could look up their heights to the metre in various tables, but there's nothing like a scale image to provide instant understanding, as in the comparison of skyscrapers on the left.

So I decided the compare the Eight-thousanders, Seven Summits and Seven Second Summits in the top-right graphic. Sadly, I had to use triangles as I did not have the actual elevation profiles of the mountains.
Neither RacerX11 nor I were satisfied with my use of symbols to show which list each mountain belonged to. There were actually 5 lists:

1. The Eight-thousanders
2. Bass's Seven Summits
3. Bass's Seven Second Summits
4. Messner's Seven Summits
5. Messner's Seven Second Summits

After throwing ideas at each other, I realised that I could group their labels as in the bottom-right graphic. RacerX11's finishing touch was to use symbols to distinguish just the 4 mountains in the Bass and Messner lists.

It would have been superb to add the Volcanic Seven Summits and Volcanic Seven Second Summits, too, but the image was already a bit cluttered, and there is controversy on the membership of the list itself.

UPDATE 31 JAN 2013: I just found out that Thomas Laussermair has written on http://visualign.wordpress.com/2012/06/04/graphic-comparing-highest-mountains/ very kind words about the image and a mod I made for him — thanks, tlausser/visualign!

## Cambridge Kings Hedges Jenny Wren bus stop RL.jpg ☎ 29 Feb 2012

Left frame
The Jenny Wren pub and bus stop with an approaching Citi 1 bus.

I borrowed a Fujifilm FinePix Real 3D W3 and went around taking photos of Cambridge in the summer of 2011.

I then developed the stereoscopic image template to let the reader view the pictures in various arrangements — though cross-eye viewing lets one view much larger images, some people find parallel viewing more comfortable. The template supports side-by-side sterescopic images in both parallel and cross-eye formats.

The first stereoscopic photograph I've uploaded to Wikimedia shows a Stagecoach Citi 1 bus in King's Hedges, a residential suburb to the north of Cambridge city centre.

## Ideal projectile motion for different angles.svg ☎ 25 Feb 2012

Trajectories of projectiles launched at different elevation angles but the same speed of 10 m/s in a vacuum and uniform downward gravity field of 10 m/s2. Points are at 0.05 s intervals and the length of their tails is linearly proportional to their speed. t = time from launch, T = time of flight, R = range and H = highest point of trajectory (indicated with arrows).

Being a markup language, SVG code can be easily generated using a program or script, as contrasted with, say, a Microsoft PowerPoint or Adobe Illustrator drawing.

As I'm already familiar with Perl (the less-abstruse constructs, at least!) I wrote scripts to automatically generate SVG code which would otherwise need lots of calculator work, such as drawing graphs. Labels and other decoration can then be manually added to complete the illustration. So that a future editor can easily tweak the code, the Perl code appends itself to the SVG as a comment.

An example is this diagram which shows how a projectile behaves when launched at different angles of elevation, in the absence of air resistance.

As is often taught in high school, a 45° angle indeed gives the greatest range. What is less known is that the time of flight increases with the angle. Since there are two complementary angles giving the same range (other than the maximum), it is possible for artillery to fire a shell at the larger angle, then another at the smaller one after an appropriate delay, so that both shells hit the target at the same time — a basic form of Multiple Rounds Simultaneous Impact.

## Moon names.svg ☎ 17 Feb 2012

Lunar nearside with major maria and craters labeled.
Erdzugewandte Seite des Mondes mit den größten Maria und Kratern gekennzeichnet.

One of the features of SVG which initially attracted me was the ability to embed a bitmap, such as a JPEG or PNG image.

This allows labels to be relatively easily updated or translated into different languages, by simply replacing the English terms in its SVG file with a text editor, as Timwi has done with the lower image on the right.

Original JPEG with "burnt-in" labels.

Before I learnt this, I had to tediously edit the image on the left to correct "sea of storms" to "sea of crises" (unable to find a matching font, I manually cut and pasted individual letters from other labels).

Even after doing so, saving the file slightly reduced the image quality, due to the lossy compression JPEG uses.

UPDATE 31 JAN 2013: http://www.motobit.com/util/base64-decoder-encoder.asp provides a useful facility to convert an image to Base64 which can then be embedded in an SVG as follows (replace png with jpeg, gif etc as needed):



## Tensegrity simple 3.gif ☎ 21 Jan 2012

Left frame
Animation Each compression member (green) is symmetric with the other two, and symmetric from end to end. Each end is connected to three cables (red) which provide compression and define the position of that end.
The simplest tensegrity structure

I had once toyed with the POV-Ray raytracer. Similar to SVG, one writes code to render an image, but in this case in 3D!

As I thought that the tensegrity article could benefit from an animation to better show the spatial relationship of structural parts, I decided to create a GIF animation of a rotating structure, as on the left.

Alas, a reader found the animation distracting, so we settled on a static image with a link to the animation. It then occurred to me to use the stereoscopic image template I had once written to display the static image, as on the right...

## Herbert Backstage Pass cmglee 65.jpg ☎ 2 Jan 2012

Group photograph at the end of Herbert Backstage Pass.

Following the success of Derby Backstage Pass, the UK chapter of the Wikimedia Foundation and Herbert Art Gallery and Museum, Coventry organised Herbert Backstage Pass on 1 October 2011. The first major Wikipedia-related event I've attended, it seemed a perfect collaboration: The museum giving Wikimedia members access to parts not normally accessible to the public as well as time and attention of curators and other staff, while the members contribute to Wikipedia articles relevant to the collection.

This photograph (right) was taken at the end of the day, sadly after several attendees had left. More photos of the event can be viewed here.

ThrustSSC

UPDATE 15 OCTOBER 2013: My visit to the Coventry Transport Museum to see ThrustSSC on that Coventry trip has just resulted in my third (as far as I can tell) image to appear on the Wikipedia main page (today's). ☻✌

## Symmetrical 5-set Venn diagram.svg ☎ 1 Jan 2012

Five-set Venn diagram using congruent ellipses in a radially symmetrical arrangement devised by Branko Grünbaum. Labels have been simplified for greater readability; for example, A denotes ABcCcDcEc (or A ∩ ~B ∩ ~C ∩ ~D ∩ ~E), while BCE denotes AcBCDcE (or ~ABC ∩ ~DE).

This image marked the start of my regular contribution of SVG drawings to Wikipedia. I found using SVG to mark up images (especially by hand or with a script) rather fascinating, albeit at times frustrating due to

1. Some design decisions of the SVG syntax (e.g. specifying label text colour with fill but line colour with stroke), and
2. Limitations of the Wikimedia SVG renderer (e.g. not properly supporting markers making arrows hard to code, and differences in text size and alignment between the rendered PNG and browser render, as can be seen by the image's long editing history).

Making this image taught me various SVG basics, such as setting the viewport, creating and transforming primitives, and using defined blocks. A trick I found is how to properly outline overlapping shapes with semi-transparent fills (the naive method causes strokes (outlines) to be overlaid, giving outlines of inconsistent colour):

Make the collection of shapes a block, and use it once with zero stroke-opacity to paint the fills, then again with zero fill-opacity to paint the strokes.

The Venn diagram itself is an aesthetic solution to the puzzle of how to represent, with just ellipses, all possible combinations of five sets with each combination appearing exactly once.[2]

Do you still have the code you used to generate the 5 way Venn diagram? I would like to know the center of the ellipsis; hence I'm asking. Thank you. Carstensen (talk) 10:00, 16 April 2013 (UTC)

1. ^ K/T extinction
2. ^ Grünbaum, Branko, "Venn Diagrams and Independent Families of Sets." Math. Mag. 48, 12-23, 1975.