Cylindrical Projection Textures from "Space photographs

[granthutchison]

I assigned 115.0 and 16.0 km for the maximum radius and height difference, as posted in the NASA site. The script that I am using displaces the primitive with those values as input. Besides, there are lighting, shading and projection variables that can make the results look way different. I still think that there is some issue with that image: despite the oblong shape, there is no corresponding hue variation to that altitude change (ie. the right side of the map should turn more and more yellowish, but it doesn't). I don't want to guess the geometry, but I'd like to discuss this.

The silhouette of the object should be pretty robust to changes in lighting, shading and projection, and it certainly looks different in the original images. Either the reported altitude difference isn't the whole story or they've exaggerated it for some misguided reason.

Grant

[Toti]

The silhouette of the object should be pretty robust to changes in lighting, shading and projection

Lighting and shading can have a virtual effect on the silhouette when the image is viewed in a non-gamma-corrected screen (like mine). I can only see the colored parts: the darker areas vanish into the background (as a consequence, the image looks oblong). Of course, adjusting gamma with adequate software shows the real geometry.
But projection does have a great impact: the first image was adquired with an orthogonal projection camera:


And this one was done with a 35 mm. "lens":


There was no other change done to the scene.
But what I meant in my last post is that even including those variables, I find difficult to explain this curious distortion. It might be in fact that it was deformed on purpose, but it doesn't make any sense in an image that attempts to portray Phoebe's true shape
Also, I am not touching the color information provided by the original image, so the cylindrical height map->3d model transform should be direct and accurate.

Anyway, I have included another Phoebe model, carefully scaled to approximate the original image contours, that were obtained by normalizing the images' sizes along the vertical axis (they have different dimensions) and then applying the threshold tool.

Probably this can be enhaced: I have posted the instructions and a script that does most of the job, so if anyone wants to try changing a few parameters, please feel free to do it.

[Cham]

Sorry, I'm unable to use your link. It says I don't have permission to use that link !!

Also, can you make a 3ds model, as I only have Celestia 1.3.1 on my Mac.

Thanks.