[GeoWeb3DContest] Rotterdam data

[Information and updates on Web3D's Rotterdam city data competition]

Correction to the vrml editor screenshot:
http://dug9.users.sourceforge.net/web3d/temp/dune_screenshot_vrml_rotterdam_afrikaanderwuk.jpg



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> To: geoweb3dcontest at web3d.org
> Date: Fri, 20 Mar 2015 13:25:27 -0600
> From: geoweb3dcontest at web3d.org
> Subject: [GeoWeb3DContest] Rotterdam data
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> The Rotterdam texture atlases appear to be completely random.
> When I open a vrml version of the afrikuunderwuk data in a vrml editor:
> http://dug9.users.sourceforge.net/web3d/temp/screenshot_dug9gui_test.jpg
> the long buidling in the lower left, I can pick chunks/sections of it, and just in the little stretch we see, there are 3 different texture files involved. So to draw that building, you'd need to load at least 3 1024x1024 image textures. That's sub-optimal.
> I don't see a pattern to how they did the textures.
> -Doug
> more..
> ROTTERDAM> AFRIKUNNDERWUK TEXTURES
> (8 x 19) + 5 ~= 160
> 160 x 1024x1024x4 = 160 x 4MB = 640MB
> with mipmapping lets say 128 layers 1.3GB
> Yes that's texture heavy.
>
> Hypotheses for seeming randomness to the texture atlases:
> H0: military requirements: they had to scramble the textures in little bits so an enemy could not reconstruct a coherent base map from the texture images
> H1: the software they used for authoring accidentally randomized
> H2: there's a pattern / a method to the madness and I just can't see it
>
> A first job of fixing might be to reconstruct a conherent base/orhtophoto texture
> Method 1: use googleEarth snapshots
> Method 2: get a vrml browser to render (however slowly) the buildings and ground as given, as seen from above. Then do a snapshot in the vrml browser to get a vertical texture. Tile those textures to get an orthophoto
> Method 3: ask Rotterdam for their original ortho images
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> Once there are coherent orthophoto textures for the ground, then the building texture coordinates would need to be re-done.
> Method A: manually
> Method B: use image correlation and search algorithms to find roof texture in orthophoto, then shift the texture coordinates
> Because there are textures for the sides of the buildings too, and if we desire per-building atlases, then
> Method C: iterate over buildings, and for each building:
> - iterate over shape faces, and for each face
> -- from texture coordinates and original atlas image, extract the pixels for that face, and place in a new per-building atlas
> and in this way automatically build per-building atlases including sides and roof
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