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fisheye on hemisphere texture mapping

April 22, 2012 | 10:16 pm

Hi all,

I’m trying to map a fisheye image onto a hemisphere mesh. I’ve gotten close, but the texture mapping is not quite right. The edges near the equator are stretched and the pole is squished. Does anyone have suggestions?

I’ve pasted the patch below. Try this fisheye image:

http://paulbourke.net/exhibition/astc2007/sponge_b.jpg

In the example you will see how the lines of the image get wavy near the equator as a result of the incorrect texture map.

Thanks,
Charles

– Pasted Max Patch, click to expand. –

April 24, 2012 | 4:50 am

Just off the top of my head, it seems that this problem could be caused by the fact that the image you are using is, in itself, a mapping of 3D data on a 2D screen. Using a texture on 3D geometry is the same thing; we see it in 2D so the GPU has to re-map it.
What you would need would be similar to a mercator projection. Perhaps someone here has made an automatic mercator converter.


April 29, 2012 | 1:36 pm

The answer is that you have to make a custom texture map. Thank you Paul Bourke:

http://paulbourke.net/texture_colour/texturemap/#fisheye


April 30, 2012 | 7:52 pm

Awesome link veasec! We’re doing some projecting in a planetarium and were looking for this exact material! Thanks so much!


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