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File:Penang island.stl

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Original file(5,120 × 2,880 pixels, file size: 2.54 MB, MIME type: application/sla)

View Penang island.stl  on viewstl.com

Summary

Description
English: Penang Island terrain 3D model based on ASTER Global DEM data by CMG Lee.
Date
Source Own work
Author Cmglee
Other versions

Python source

#!/usr/bin/env python

header    = 'Penang Island terrain 3D model based on ASTER Global DEM data by CMG Lee.'
path_dem  = 'Penang_Island_heightmap_ASTGTM2_N05E100_dem_20pc.png'
scale     = 5e-2
thickness = 1

import re, struct, math, png
def fmt(string): ## string.format(**vars()) using tags {expression!format} by CMG Lee
 def f(tag): i_sep = tag.rfind('!'); return (re.sub('\.0+$', '', str(eval(tag[1:-1])))
  if (i_sep < 0) else ('{:%s}' % tag[i_sep + 1:-1]).format(eval(tag[1:i_sep])))
 return (re.sub(r'(?<!{){[^{}]+}', lambda m:f(m.group()), string)
         .replace('{{', '{').replace('}}', '}'))
def append(obj, string): return obj.append(fmt(string))
def tabbify(cellss, separator='|'):
 cellpadss = [list(rows) + [''] * (len(max(cellss, key=len)) - len(rows)) for rows in cellss]
 fmts = ['%%%ds' % (max([len(str(cell)) for cell in cols])) for cols in zip(*cellpadss)]
 return '\n'.join([separator.join(fmts) % tuple(rows) for rows in cellpadss])
def hex_rgb(colour): ## convert [#]RGB to #RRGGBB and [#]RRGGBB to #RRGGBB
 return '#%s' % (colour if len(colour) > 4 else ''.join([c * 2 for c in colour])).lstrip('#')
def viscam_colour(colour):
 colour_hex      = hex_rgb(colour)
 colour_top5bits = [int(colour_hex[i:i+2], 16) >> 3 for i in range(1,7,2)]
 return (1 << 15) + (colour_top5bits[0] << 10) + (colour_top5bits[1] << 5) + colour_top5bits[2]
def roundm(x, multiple=1):
 if   (isinstance(x, tuple)): return tuple(roundm(list(x), multiple))
 elif (isinstance(x, list )): return [roundm(x_i, multiple) for x_i in x]
 else: return int(math.floor(float(x) / multiple + 0.5)) * multiple
def flatten(lss): return [l for ls in lss for l in ls]
def rotate(facetss, degs): ## around x then y then z axes
 (deg_x,deg_y,deg_z) = degs
 (sin_x,cos_x) = (math.sin(math.radians(deg_x)), math.cos(math.radians(deg_x)))
 (sin_y,cos_y) = (math.sin(math.radians(deg_y)), math.cos(math.radians(deg_y)))
 (sin_z,cos_z) = (math.sin(math.radians(deg_z)), math.cos(math.radians(deg_z)))
 facet_rotatess = []
 for facets in facetss:
  facet_rotates = []
  for i_point in range(4):
   (x, y, z) = [facets[3 * i_point + i_xyz] for i_xyz in range(3)]
   if (x is None or y is None or z is None):
    facet_rotates += [x, y, z]
   else:
    (y, z) = (y * cos_x - z * sin_x,  y * sin_x + z * cos_x) ## rotate about x
    (x, z) = (x * cos_y + z * sin_y, -x * sin_y + z * cos_y) ## rotate about y
    (x, y) = (x * cos_z - y * sin_z,  x * sin_z + y * cos_z) ## rotate about z
    facet_rotates += [round(value, 9) for value in [x, y, z]]
  facet_rotatess.append(facet_rotates)
 return facet_rotatess
def translate(facetss, ds): ## ds = (dx,dy,dz)
 return [facets[:3] + [facets[3 * i_point + i_xyz] + ds[i_xyz]
                       for i_point in range(1,4) for i_xyz in range(3)]
         for facets in facetss]

## Read elevation data
(map_width, map_height, map_pixels, map_metadatas) = png.Reader(path_dem).read_flat()
print(map_width, map_height, len(map_pixels), map_metadatas)
heightss = [[map_pixels[4 * (map_width * y + x) + 1]
             for y in range(map_height)] for x in range(map_width)]

## Add facets
facetss = []
for y in range(map_height - 1):
 for x in range(map_width - 1):
  (x0, y0, x1, y1) = (x, -y, x + 1, -(y + 1))
  z00 = heightss[x    ][y    ] * scale
  z01 = heightss[x    ][y + 1] * scale
  z11 = heightss[x + 1][y + 1] * scale
  z10 = heightss[x + 1][y    ] * scale
  if (abs(z00 - z11) < abs(z01 - z10)):
   if (z11 != 0 or z10 != 0 or z00 != 0):
    facetss.append([None,0,0,  x1,y1,z11,  x1,y0,z10,  x0,y0,z00])
   if (z00 != 0 or z01 != 0 or z11 != 0):
    facetss.append([None,0,0,  x0,y0,z00,  x0,y1,z01,  x1,y1,z11])
  else:
   if (z10 != 0 or z00 != 0 or z01 != 0):
    facetss.append([None,0,0,  x1,y0,z10,  x0,y0,z00,  x0,y1,z01])
   if (z01 != 0 or z11 != 0 or z10 != 0):
    facetss.append([None,0,0,  x0,y1,z01,  x1,y1,z11,  x1,y0,z10])
  # sys.stdout.write(chr(int(math.ceil(heightss[x][y] * 0.1)) + 32))
 # print('')
# writer = png.Writer(width=map_width, height=map_height, alpha=map_metadatas['alpha'])
# writer.write_array(open('test.png', 'wb'), map_pixels)
facetss += [facets[0: 5] + [max(0, facets[ 5] - thickness)] +
            facets[9:11] + [max(0, facets[11] - thickness)] +
            facets[6: 8] + [max(0, facets[ 8] - thickness)] for facets in facetss]
# facetss = [facets[:3] + facets[6:9] + facets[3:6] + facets[9:] for facets in facetss] ## flip

## Calculate normals
for facets in facetss:
 if (facets[0] is None or facets[1] is None or facets[2] is None):
  us      = [facets[i_xyz + 9] - facets[i_xyz + 6] for i_xyz in range(3)]
  vs      = [facets[i_xyz + 6] - facets[i_xyz + 3] for i_xyz in range(3)]
  normals = [us[1]*vs[2] - us[2]*vs[1], us[2]*vs[0] - us[0]*vs[2], us[0]*vs[1] - us[1]*vs[0]]
  normal_length = sum([component * component for component in normals]) ** 0.5
  facets[:3] = [-round(component / normal_length, 10) for component in normals]

# print(tabbify([['N%s'  % (xyz   )                   for xyz in list('xyz')] +
#                ['%s%d' % (xyz, n) for n in range(3) for xyz in list('XYZ')] + ['RGB']] + facetss))
## Compile STL
outss = ([[('STL\n\n%-73s\n\n' % (header[:73])).encode('utf-8'), struct.pack('<L',len(facetss))]] +
         [[struct.pack('<f',float(value)) for value in facets[:12]] +
          [struct.pack('<H',0 if (len(facets) <= 12) else
                            viscam_colour(facets[12]))] for facets in facetss])
out   = b''.join([bytes(out) for outs in outss for out in outs])
# out += ('\n\n## Python script to generate STL\n\n%s\n' % (open(__file__).read())).encode('utf-8')
print("# bytes:%d\t# facets:%d\ttitle:\"%-73s\"" % (len(out), len(facetss), header[:73]))
with open(__file__[:__file__.rfind('.')] + '.stl', 'wb') as f_out: f_out.write(out)

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons

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You are free:
  • to share – to copy, distribute and transmit the work
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Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

Wikimedia Foundation
The uploader of this file has agreed to the Wikimedia Foundation 3D patent license: This file and any 3D objects depicted in the file are both my own work. I hereby grant to each user, maker, or distributor of the object depicted in the file a worldwide, royalty-free, fully-paid-up, nonexclusive, irrevocable and perpetual license at no additional cost under any patent or patent application I own now or in the future, to make, have made, use, offer to sell, sell, import, and distribute this file and any 3D objects depicted in the file that would otherwise infringe any claims of any patents I hold now or in the future.

Please note that in the event of any differences in meaning or interpretation between the original English version of this license and a translation, the original English version takes precedence.

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current12:54, 31 March 2018Thumbnail for version as of 12:54, 31 March 20185,120 × 2,880 (2.54 MB)CmgleeUser created page with UploadWizard
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