Talk:Contour line

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contour crossings[edit]

Yes, at a saddle point. Charles Matthews 08:26, 25 January 2006 (UTC)
Also at a shear cliff the lines will lie on top of each other. You can have the contours cross completely for multivalued functions. The geographic equivalent would be an large overhanging piece of rock. The contour corrisponding to the altitude that is the top surface of the rock (or a fraction below it in fact) would follow the edge of the overhang. The contour for the altitude just above the ground ok? beneath the overhang would go right up to the cliff wall, intersecting the higher one. This would create a zone (for example) that belonged to both "Above 100m" and "Below 50m" simultaneously, which is of course possible if the ground is at 45m and with an overhang at 105m. —The preceding unsigned comment was added by (talk) 13:52, 17 March 2006 (UTC)


How did early map makers estimate contour lines? or put another way, how did they know their level according to sea level? i understand the use of altimeters, but not the practise. —The preceding unsigned comment was added by (talk) 18:34, 13 February 2006 (UTC)

answer: see surveying article.--Natcase 04:36, 21 December 2006 (UTC)

See a dictionary while your at it. —Preceding unsigned comment added by (talk) 12:45, 14 January 2009 (UTC)


ok to merge isoline into contour real diff Anlace 14:20, 1 June 2006 (UTC)

isoline/contour line, very much the same thing, merge is good idea User:LordHarris 22 June 2006

merger completed content was lost Anlace 08:20, 2 July 2006 (UTC)

Contour map should redirect here, not to topo map[edit]

just look how many different applications are served here. that redirect seems appropriate to arrive at this article.Covalent 23:39, 17 September 2006 (UTC)

done. --Natcase 04:36, 21 December 2006 (UTC)


I suggest merging all (or nearly all) of the "iso-" article stubs into this single article, organized by subject area. I've reorgnized the list of isopleth types as a starter. There are generally references to thematic articles (for example light pollution for isophote), which put the specific example into a good context. I'm putting merge markers on a bunch of them tonight.--Natcase 04:36, 21 December 2006 (UTC)

oppose myriad mergers. this will lead to a very large unwieldy article when the topics are fleshed out. Anlace 05:05, 21 December 2006 (UTC)
I revise my suggestion. Some current links go to irrelevant articles (isochrone for example has nothing to do with drive time) and should be delinked. Others are clearly important in their subject areas (isogloss for example), so a more judicious mix of moving stubs here, and referencing full articles, and more disambiguating terms with multiple uses... this could be a bit of a project. My goal, Anlace, is to get rid of the stubs that are essentially Wiktionary entries, and which if fleshed out would largely repeat what should be said generally under "contour lines." See isobar for examples of content that ought to be here.--Natcase 05:10, 21 December 2006 (UTC)
This revised intent sounds fine and i support revised merger. I suppose we can always do a split if someone can create a large article out of one of the merged stubs. regards. Anlace 05:45, 21 December 2006 (UTC)

As far as I tell from a quick Internet search, in English the word "isohypse" is mainly used with its specific meaning in meteorology. In geology, it is sometimes used as an alternative to "contour line" for describing the boundary between rock formations. I haven't found it being used to refer to land surface contours, except in text that seems to be based on Wikipedia, or in text in German (it seems that "isohypse" and "Höhenlinie" are both used to mean contour line). Therefore I suggest that isohypse is kept just for its meteorological meaning (or as a redirect to a meteorological article); the lurid example image could be moved to cartographic relief depiction. JonH 12:37, 21 December 2006 (UTC)

The list of "iso-"s feels a little like the "encyclopedic" lists of names phobias. I like how -phob- handles this, seeing also phobia and specific phobias (though inthis case I don't think we need three articles. I think non-list sections by area of study would help give some sense of context and perspective to the whole. Though I won't place bets on someone with a bent for lists coming in later and resurrecting the lists themselves (maybe that's why we need a separate article for the list). In an encyclopedic sense, I thinks the current list is missing things. Not sure what, but we could probably invent some cool iso's ourselves. Isowiki, for example (lines showing equal density of wikipedia article writers as a percentage of the general population) —The preceding unsigned comment was added by Natcase (talkcontribs) 05:47, 22 December 2006 (UTC).

merging has begun. cleanup and expansion are needed...--Natcase 04:40, 10 January 2007 (UTC) merge is now complete as proposed; removing merge proposal header.--Natcase 16:14, 13 January 2007 (UTC)

In 2007, the merge did not include Isoclinic line, Aclinic line, or Isodynamic line. But these are also no more than dictionary definitions, just like the original Isogon (geomagnetism) article. I have already included them in Contour line#Magenetism, so all that needs to be done is to change the articles into redirects, so that readers will see the complete family of geomagnetic contour lines. I think the redirects Magnetic equator and Geomagnetic equator would be best if they went directly to Magnetic dip. JonH (talk) 13:17, 7 March 2010 (UTC)

Lost contours[edit]

for a long time this article listed "air quality contour" and "noise contour" as recognized terms. these terms are in fact extremely common and important in the fields of urban planning, highway design and environmental health. where did these go? they must be restored. regards. Anlace 16:42, 10 January 2007 (UTC)

The links went away becaue the list was for specific names of contour types, not types of maps where contours are used. Those two listings were in the form of "noise: countour line" instead of "noise: isodecibel" or whatever the term (if any). You are right, they should be in here somewhere. The point was made above that "isohypse" (for example) is infrequently used, and I suspect a lot of the other "iso's" are spurious or at least infrequently used, and so perhaps the "list of isos" should be modified to be a more general list of subject areas, whether the used specialized terminology or the more generic "contour line."
The question raises another one, though. We should include at least some discussion of 3-dimensional visualizations using contours. I know nothing about them though; anyone?--Natcase 04:14, 12 January 2007 (UTC)
so where should the air quality and noise contours be discussed. under meteorology? or under an other environmental factors heading? i could add something to the 3-D issue but it is a vacuous discussion without a good graphic. Anlace 04:48, 12 January 2007 (UTC)
I've altered the format to make it more article-like and less list-like; there is now a place for enironmental science. Feel free to rewrite/replace the filler I added.--Natcase 13:58, 12 January 2007 (UTC)

Specifics on non-map applications?[edit]

So far, all the specificity applies to map applications. Some specific discussion on non-map applications would be welcome. Any suggestions on existing wiki sources to pull from?--Natcase 23:41, 23 January 2007 (UTC)

i agree. i will work on this as i have time. its on my "to do" list. there are some speciifcs that can be pulled in from noise barrier for example. Anlace 00:33, 24 January 2007 (UTC)
Isobars (for constant pressure), isotherms, and other iso-lines are used in graphs in thermodynamics and other science and engineering applications. They are useful in representing more than two dimensions on a two dimensional graph. I think some discussion on this would be useful somwhere in Wikipedia. H Padleckas 00:52, 11 August 2007 (UTC)


No mention of isohypses in section on meteorology. No mention of constant pressure charts. No met categories either. JMcC 13:20, 3 April 2007 (UTC)

For my comments on the use of the word isohypse, see the "merge" section further up this page. The existing surface weather analysis article is already quite long, but it does not really discuss air pressure. I think there needs to be a new article that describes how air pressure affects the wind (and it could explain the use of charts that show isobars and isohypses), but I do not know enough about meteorology to write such an article. JonH 13:08, 4 April 2007 (UTC)
Perhaps a categorization in 'Meteorology'as well? —Preceding unsigned comment added by Rajpaj (talkcontribs) 11:36, 21 May 2011 (UTC)

Line colour[edit]

I have removed the claim that "the Ordnance Survey changes contour lines from brown to grey to indicate bare rock and scree." I use OS maps a lot and have never seen this distinction. At both 1:25000 and 1:50000 scales, contour lines are always brown. Rock and scree are shown using other symbols. However, certain Swiss topo maps do use grey contour lines on rocky ground. It is much clearer IMHO. 16:53, 9 May 2007 (UTC)

image demoing concept[edit]

Contour lines

I'd like to add this image to the article. Anyone agree/disagree?-Ravedave 04:10, 15 June 2007 (UTC)

  • It looks good to me. JonH 08:52, 15 June 2007 (UTC)
Looks like a nice image. Add it with the proper context somewhere in this article. H Padleckas 01:02, 11 August 2007 (UTC)

uh and[edit]

all comics and manga, all sketch art, flash art, Bizantine art...basically everything, or this not the appropriate term in american English? --AnY FOUR! 04:38, 27 July 2007 (UTC)

Yes, the proper term in American English for what you describe is "outline." There may be some further discussion in articles on art, not sure. --Natcase 20:39, 5 August 2007 (UTC)

WikiProject class rating[edit]

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:46, 10 November 2007 (UTC)

Contour line question[edit]

How are caves and overhangs "handled"/shown with contour lines? Jackiespeel (talk) 23:00, 7 December 2007 (UTC)

Contour interval and disambiguation[edit]

It was proposed some time ago that Contour interval be merged into this article. Not a lot there to merge, but I'm OK with that. Without objection, I'll do it soon

I also think we should create a separate disambig page, and move the various disambigs there. okeydokey?--Natcase (talk) 20:07, 17 August 2008 (UTC)

It's good to see you are still caring for this page. Some time ago, I also thought contour should be a proper disambiguation page, and wrote the following draft. But I didn't get around to making the edit, mainly because I realised there are about 50 pages linking to it which need to be changed. Most need to link to contour line, but a few should link to contour integration, while others just use the word contour in a general sense. JonH (talk) 17:13, 18 August 2008 (UTC)
[The draft has now been used as the basis for the contour page]
Disambig page added and the merge from contour interval. I left out the table from contour interval; it seems to be generated against a specific scale of map. If someone wants to figure out what it means, fix it and reinsert it, that would be fine with me.--Natcase (talk) 02:18, 1 September 2008 (UTC). Links to Contour fixed, mostly.--Natcase (talk) 02:17, 2 September 2008 (UTC)
Good work! I have made some minor changes to contour, and changed contours so it just redirects to contour. JonH (talk) 19:08, 6 October 2008 (UTC)

edits to lead[edit]

In copyediting the lead, I retained the general mathematical definition first, even though it is, IMO, more difficult to understand than one in terms of maps. I also notice that the previous version specifically mentioned cartography, so would it be better to say "In cartography, …" somewhere in the lead? --Jtir (talk) 21:15, 10 September 2008 (UTC)

I think math first is better, as it is more general. And yes, probably good to mention cartography. Certainly that's what a lot of folks will be coming here for. I'd actually like to get more about the use of contour curves in intergral calculus, but don't have any expertise.--Natcase (talk) 23:59, 10 September 2008 (UTC)
A more detailed mathematical description of contour lines would be a useful addition. I'm thinking of that in Courant and Robbins or Courant and McShane. Line integral already mentions contour integrals as a special case of integration.
What did you have in mind?
FWIW, I came across this article while looking for info on interpolation between contour lines.
--Jtir (talk) 20:42, 13 September 2008 (UTC)
I had nothing specific in mind, but the leap from math to cartography was too sudden for me. I like your changes.--Natcase (talk) 21:48, 13 September 2008 (UTC)


I found it a little odd that Isopleth redirects to here (Contour line), while Isopleths is a stub-class article in its own right. Is there any sensible reason why this should be so? --RexxS (talk) 04:02, 4 January 2009 (UTC) No, here isn't a good reason. Someone should join it in. Looks like duplicate content.--Natcase (talk) 00:47, 11 February 2009 (UTC)

merged--Natcase (talk) 13:43, 26 February 2009 (UTC)

Index Contours[edit]

Article doesn't mention anything about index contours, be nice to add that somewhere. —Preceding unsigned comment added by Snazzyy (talkcontribs) 01:40, 10 February 2009 (UTC)

Lines of equal travel time[edit]

How about adding some travel-time contour maps, e.g. the rather excellent Ojw (talk) 17:49, 28 October 2009 (UTC)


I have incorporated the "Courbe niveau" diagram (shown above under "image demoing concept") into the article. I have also moved the example of a topographic map further down the article to replace the previous brightly colored relief diagram.

I am not sure what to do about the "Mathematical contour plot" image. Judging by the vandalism that this article receives, many of its readers are school children, and I fear that instead of seeing contour lines as quite a simple concept (lines joining points of equal value) they will look at the image and give up because they do not understand trigonometric functions. The image looks interesting, but it is confusing because it emphasizes the colored areas between the contour lines instead of the lines themselves, and it needs the complicated caption just to explain where the function is zero. Would anyone object if I removed the image? JonH (talk) 15:11, 24 November 2009 (UTC)


But it reads "Mathematical contour plot." Not all readers are schoolkids; some, say in college math, may profit.

dino (talk) 17:45, 24 November 2009 (UTC)

Suggestion: contour plot algorithms?[edit]

Algorithms to draw/find the lines contour plots aught to be notable and mentioned. (talk) 21:14, 15 March 2011 (UTC)

Not necessarily. More than likely, these were made with Mathematica. In that program, you simply coodinate your contour plot. —Preceding unsigned comment added by Rajpaj (talkcontribs) 13:40, 21 May 2011 (UTC)
see level set method - boundaries of level sets are contour lines, equipotential alines are contour lines. Algorithms can be : boundary detection or boundary tracing.--Adam majewski (talk) 09:57, 2 October 2011 (UTC)

I need help,[edit]

I was directed to this page by User:Opbeith to have a request solved.Can anyone help me.

Can anyone get close to any climate organisation e.g NASA or others to get climate information on Nigeria containing average rainfall for all nigerian regions and use isohyets or contour lines to contruct the rainfall information of Nigeria for the Geography of Nigeria article and arrange them on the map in the format provided below.

0 mm   - 500mm
500mm  - 750mm
750mm  - 1000mm
1000mm - 1250mm
1250mm - 1500mm
1500mm - 1850mm
1850mm - 2000mm
2000mm - 2500mm
2500mm - 3000mm
3000mm - 3500mm
3500mm - 4000mm
above 4000mm.
thanks Netknowle message me!  05:05, 13 June 2011 (UTC)

Contour line(disambiguation))[edit]

Hi. What do you think about dividing this article in 2 : countout line(geographic) and contour line ( math ) ? --Adam majewski (talk) 09:59, 2 October 2011 (UTC)

This is definitely required. 99% of readers arriving on this page just want to know about contour lines on maps. They do not need a discussion of mathematical functions. Likewise, those who are looking for the maths just want the maths. These articles should never have been merged (admittedly back in 2006, when this may not have been obvious). JA Translator (talk) 21:02, 6 February 2019 (UTC)

Possible unwarranted promotion[edit]

"When maps with contour lines became common, the idea spread to other applications. Perhaps the latest to develop are air quality and noise pollution contour maps, which first appeared in the US, in approximately 1970, largely as a result of national legislation requiring spatial delineation of these parameters. In 2007, Pictometry International was the first to allow users to dynamically generate elevation contour lines to be laid over oblique images."

I'm an industry outsider but it seems unlikely that Pictometry International are significant enough to warrant that mention - indeed it reads as blatant advertising. Thoughts?

Question about the term Isotherm[edit]

When I typed in Isotherm in wikipedia, it directed me to contour lines. While the topics are very similar, and the definition of an Isotherm is adequate, I still think there should be more information on how the concept of an Isotherm was created. Maybe include a historical section mentioning the impact that Alexander Von Humboldt had regarding his studies on the correlation between vegetation and climate, which led to the assimilation of climates and there ecosystems across the globe. Just a thought.


(Mrjohnson007 (talk) 02:34, 11 February 2014 (UTC))

I just added a line mentioning Humboldt's coining of the term and first published map of isotherms. (Could also be moved in part or in whole into the history section.) Perhaps someone else could add a link from that pointing back to the Humboldt article. (talk) 06:39, 22 September 2016 (UTC) (Pfeiffer)

Is "isochalaz" a hoax?[edit]

"Isochalaz" only appears in word lists. I can't find it in any journal, or in actual real use anywhere. Equinox 03:51, 20 November 2016 (UTC)

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