Viewing conditions for informational overlay textures

[timcrews]

Hello:

I am sure this is not one of the originally intended uses for Celestia, but one of the things I currently use it for is to view various overlay textures for the Earth that convey information about different areas. These overlay textures are not visual representations of the appearance of the Earth. Instead, they convey information such as land cover type, ocean temperature, base elevation, etc.

When viewing these alternate textures, I am not at all concerned with visual realism. I only want to see the textures as clearly as possible, so I can closely study the information they convey.

In the Development thread, I have requested the ability to set ambient lighting to high (i.e., equally lit from all directions.) That way, I don't have to keep messing with the time values to make sure the Sun is directly over the portion of the Earth I am viewing.

I have already set the HazeDensity to 0.0.

What should I set the specular settings to, in order to avoid all specularity? I have experimented, but I have not accomplished this.

In general, it seems even on the fully sunlit side of the Earth, that the information is more dimly lit than is the original texture when viewed outside of Celestia. Are there any other settings that might be affecting this?

Thanks for any advice,

Tim Crews

[selden]

Tim,

I don't see any script commands that would affect specularity, unlike the light level. Apparently it's strictly a function of the specularity value declared in an .SSC file.

I assume you're using AltSurface declarations to display your surface textures. With no specularity level defined, you shouldn't see any highlights.

Would you be willing to provide a copy of a surface texture that's giving you problems?

My e'mail address is available using the appropriate button below.

[timcrews]

Selden:

Ah, I see now that simply removing the Specular-related directives from the AltSurface declaration does the job of eliminating specularity. For some reason, I thought that I needed the specular directive, but with some value that resulted in zero specularity. I assumed that a lack of a directive would result in some default (non-zero) specularity. I have removed the Specular directives and no longer have any problems seeing what I want to see.

But even when I still did have specularity problems under normal ambient light levels, it turns out that your advice from the thread in the development forum (setting ambient light to 1.0) also eliminates specularity. Interesting. [Later edit: This lack of specular reflections was not caused by the ambient light being set to 1.0. It was because I had temporarily specified the desired texture as an Overlay texture instead of the main texture. The Overlay texture doesn't exhibit specular reflections.]

Unless your e-mail box can handle a 450MB file, I don't think I can send you the texture! It's the 32K land-cover VT discussed in the Textures forum.

Thanks for your help,

Tim Crews

[selden]

Tim,

no, 450MB is a bit more than the mail system would accept

But I'd expect that a 1Kx512 non-VT version would show similar display problems -- although the coloration wouldn't be particularly useful.

[Arcturus]

In the Development thread, I have requested the ability to set ambient lighting to high (i.e., equally lit from all directions.) That way, I don't have to keep messing with the time values to make sure the Sun is directly over the portion of the Earth I am viewing.

Simply add the line :

Emissive true

in the script after Texture XXX and the object is lighted from all directions at once (which also means that bumpmaps are useless as there are no shadows anymore if they are not present in the texture).

Ron