Reflection Map

[soulburn3d]

Well, there's a lot of terminology here, and it's different depending on what software you're using. A reflectance map is a map that determines how reflective a surface is at a specific spot, which is what you're describing, black is not reflective, white is very reflective. Some software also calls this a reflection map. However, in some software a reflection map is a bitmap that simulates the environment your object is in, and it will appear in reflections. Personally I prefer the name environment map for this sort of thing.

Anyways, I think the reason you're not seeing a proper result on your cube is because of this phenomenon...

http://www.neilblevins.com/cg_education/flat_metallic_surfaces/flat_metallic_surfaces.htm

Try it on a sphere and see if it works. And, let us know what software you're using.

- Neil

[danfitchie]

Thankyou for the reply mate. After reading the texturing for dummies threads post by Leah i think it was on these forums i noticed that a lot of it is to do with different terminolgies.

Just a question about what you said about environment maps, do you mean like HDR maps?
I use max so if i created say a specularity map in PS and then applied it to the model, it would make it look shiny but what if i wanted to say paint a diffuse map for i dont know a plane for instance and then paint another map so that only certain parts of that planes diffuse texture relfect the environment in max that the plane is in- without using a fake HDR map of a say kitchen. Is that different to what you suggested?

[soulburn3d]

Just a question about what you said about environment maps, do you mean like HDR maps?

All an HDR image is is an image that contains colors brighter than 1. However, they are frequently used as environment maps yes.

I use max so if i created say a specularity map in PS and then applied it to the model, it would make it look shiny but what if i wanted to say paint a diffuse map for i dont know a plane for instance and then paint another map so that only certain parts of that planes diffuse texture relfect the environment in max that the plane is in- without using a fake HDR map of a say kitchen. Is that different to what you suggested?

That is one hell of a long sentense there :) A diffuse texture does not reflect an environment. A specular reflection (which is the proper term for what you're calling a reflection) sits ontop of your diffuse texture. In max and most other software, a specular reflection is broken up into two parts, the specular highlight and the reflection. A specular highlight is a specular reflection of a point light source (such as an omni light, or spotlight in max). So if you adjust the parameters such as glossiness, or you create a specular map, you are adjusting the size and strength of your specular highlight. The reflection is everything else, and usually requires a process called raytracing to capture this sort of reflection. To do raytracing you need to use a material such as the raytrace material, that works inside of max's scanline renderer, or you need to use a third party renderer such as Brazil, Mentalray (which comes with max), vray, etc. Each material that works with these renderers deal with reflections slightly differently But if you don't want to use an environment map, then just make your material reflective, paint a reflect map to varty the amount of reflectivity, assign it and hit render.

I highly recommend a few more tutorials that discuss this stuff in more depth...

http://www.neilblevins.com/cg_education/metal_and_refs/metal_and_refs.htm
http://www.neilblevins.com/cg_education/chrome/chrome.htm

- Neil

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