Vesta model

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chris
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Re: Vesta model

Post #21by chris » 17.12.2011, 03:31

t00fri wrote:
chris wrote:I'll try generating a version of the Vesta model that uses a cylindrical texture mapping. It shouldn't be too difficult. Hopefully, the cylindrical map is well-aligned with the 3D model (I mention it, because I recall reading somewhere that the map uses a new planetographic coordinate system.)

Thanks! That should be very useful for gaining more experience with this issue.

It will actually require more effort than I'd originally thought. The mesh vertices aren't aligned with respect to any meridian. Thus, it's necessary to split any triangles that cross the 0 degree meridian (or whichever meridian one chooses for the vertical edges of the texture.) It's not incredibly difficult to do, but this complication means that the task requires more than a trivial Python or perl script.

--Chris

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t00fri
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Re: Vesta model

Post #22by t00fri » 17.12.2011, 12:58

Too bad...

As to your uniform vesta color assignment, I suppose, it is also part of the binary vesta.cmod settings that users cannot edit. The Color [. . .] statement in shadermodel.dsc does not allow to modify the color of vesta.

Fridger
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t00fri
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Re: Vesta model

Post #23by t00fri » 18.12.2011, 11:45

Here is another interesting "synthetic true color" image of Vesta
http://www-b.jpl.nasa.gov/spaceimages/d ... d=PIA14973
Image

Caption (quoted)
...
This is an RGB composite image where red is set as the 700nm band, green is set as the 550nm band and blue is set as the 440nm band. The wavelength of red light is around 700nm, of green light is around 550nm and of blue light is around 440nm, so this image approximates what the human eye would see looking at Vesta. It is an approximation because the human eye can see many more wavelengths than the three used here. This image shows the diverse colors of Vesta's surface: the left and middle parts of the image are dominated by reddish hues and the right part of the image is more blue in color.

A uniform coloration (without using a surface texture) is unable to do justice to these subtle shades of color.

Vesta_Chris.jpg


For a more precise evaluation the .tif format should of course be used instead of the .jpg displayed here.

Fridger
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