Note that this is part 5 of our tutorial – you may need to start at the beginning.
We’ve got a model and a colour scheme – that’s it, right?
Well there’s one more step to the process. While the diffuse skin tells the model what colour to be, it’s the job of the specular texture to determine what each part of the model is made of and how it reacts to light.
Here we will be working with individual colour channels in the image.
In the specular texture, the red channel indicates how specular a surface is – how much light bounces off it. Metals for example will have a lot of red, while paint will have less. A value of zero results in a surface that almost doesn’t pick up light at all, a perfect black-body.
The green channel indicates how polished and smooth the surface is. The more green, the brighter and sharper the reflection, while less green makes the reflection blurry and dull. Polished stainless and aluminium will often have very high green values, while mild steel would be moderate, and cracked paint would have almost none of either red or green.
The blue channel indicates how emissive the surface is. The higher the value, the more light it generates (and the more it ignores the lighting around it). This is used for LEDs, backlit screens or other equipment that may have light-emitting components.
Step 1:
Open up (or continue using) the layers from your Diffuse texture made in the previous section.
Step 2:
Block out the materials that most of the areas are in. If your entire model is made out of one material, this is as easy as filling the image with a colour. Try not to use true black or true white, as these can lead to excessive results.
Step 3:
Trace or overlay any areas of particular brightness or darkness.
Step 4:
Trace or overlay any areas where light is emitted.
Again, we suggest resizing your image to 512x512px before saving, as this is the ideal balance between file-size and quality for ARDI applications.