04. Finalising diffuse map
Add weathering to the wall by importing greyscale grunge maps and multiply the layer in Photoshop so they blend in with the wall texture. I like to fake ambient occlusion to some areas of the walls by painting in soft black areas and setting opacity to low, this helps to give the asset some definition when it’s baked in the engine. It's quick and dirty, but gives the effect I am looking for. Adding details like graffiti to the texture page gives it more realism.
Making a natural wall surface
Colouring your brick work with different shades of white, grey and black will give your normal map an uneven surface, pushing and pulling the individual bricks in and out and enhancing the natural, realistic look we are attempting to achieve
05. Specular map
The specular map gives lighting information for our surfaces. The whiter the texture the more specular or gloss it will have, the darker the texture the more matte it will be.
In this example, you can see the metallic garage door will be quite a shiny surface, so it is almost completely white in our texture; the brick work would not be shiny so it is a dark grey. Keep the dirty grunge texture included as this will help to show a variation of specular levels on the surface.
06. Creating the Normal map
Use a greyscale version of the diffuse (height) map as a base and start to paint over light and dark areas that you want to be pushed in or pulled out in the normal map. Remove the grunge and graffiti layers from your height map, then bring it into CrazyBump.
Once CrazyBump has finish calculating the normals, turn the medium to large details right down to reduce lumpy, rounded edges; keep the fine detail high to pick out the rough concrete surface details.
Stitch edge tools are very handy. Selecting an edge and clicking the Stitch tool will move and weld the correct UV cluster – perfect for manually unwrapping complex assets
Expert tip: Using the UV layer as a guide
Duplicate the UV render, move it to the top of the layer stack and set it to Colour Dodge. This provides guidelines to work with so you can correctly line up textures to the model.
Words: Andrew Finch
Andrew is a senior environment and lighting artist at Codemasters Game Studio in Birmingham. He has been in the industry for seven years.
This article first appeared in issue 188 of 3D World magazine.
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