Tile parsing error uVertexCount

[bertt]

I'm trying to parse a terrain tile with the following code but got an error about uVertexCount. Tile 1608.zip I've checked the Gzip compression. Tile is rendered well in the Cesium viewer.

Code:

from quantized_mesh_tile.global_geodetic import GlobalGeodetic
from quantized_mesh_tile.terrain import TerrainTile
geodetic = GlobalGeodetic(True)
[z, x, y] = [11,2107,1608]
[minx, miny, maxx, maxy] = geodetic.TileBounds(x, y, z)
ter = TerrainTile(west=minx, south=miny, east=maxx, north=maxy)
ter.fromFile('1608.terrain')

Stacktrace:

Traceback (most recent call last):
  File "test.py", line 24, in <module>
    ter.fromFile('1608.terrain')
  File "C:\Python27\lib\site-packages\quantized_mesh_tile\terrain.py", line 433, in fromFile
    self.fromStringIO(f, hasLighting=hasLighting, hasWatermask=hasWatermask)
  File "C:\Python27\lib\site-packages\quantized_mesh_tile\terrain.py", line 334, in fromStringIO
    unpackEntry(f, TerrainTile.vertexData['uVertexCount'])
  File "C:\Python27\lib\site-packages\quantized_mesh_tile\utils.py", line 19, in unpackEntry
    return unpack('<%s' % entry, f.read(calcsize(entry)))[0]
struct.error: unpack requires a string argument of length 2

Any idea whats going on?

[loicgasser]

Hi this seems a very similar error to ; https://github.com/loicgasser/quantized-mesh-tile/issues/15

[bertt]

yes looks very similar :-) but in this case got the same error on other OS (Ubuntu) so I suspect its something else.

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/quantized_mesh_tile/terrain.py", line 433, in fromFile
    self.fromStringIO(f, hasLighting=hasLighting, hasWatermask=hasWatermask)
  File "/usr/local/lib/python2.7/dist-packages/quantized_mesh_tile/terrain.py", line 334, in fromStringIO
    unpackEntry(f, TerrainTile.vertexData['uVertexCount'])
  File "/usr/local/lib/python2.7/dist-packages/quantized_mesh_tile/utils.py", line 19, in unpackEntry
    return unpack('<%s' % entry, f.read(calcsize(entry)))[0]
struct.error: unpack requires a string argument of length 2

[loicgasser]

in the attached file the tile coordinates are not the same as in the code sample. 739397 seems to be the value for x.

Are you sure about z,x,y tile coordinates?

[bertt]

yes should be 11,2107,1608. Where did you get the value x=739397 from? I don't see it in the header.

[loicgasser]

I got it from the filename, are those Cesium tile? Where did you get it from? I'll try it out on my machine.

[bertt]

Tiles are produced by running ctb-tile on a tif file, for example http://www.rijkswaterstaat.nl/apps/geoservices/geodata/dmc/ahn2_05_int/geogegevens/raster/01_09/i09bz1.tif

[loicgasser]

That's a heightmap terrain format not quantized mesh (regular triangles)

See: https://github.com/AnalyticalGraphicsInc/cesium/wiki/heightmap-1.0-terrain-format and https://cesiumjs.org/data-and-assets/terrain/formats/quantized-mesh-1.0.html