Once you have finished, create another weight map called "Dents" (with initial value of 0%) and use the airbrush again, but this time painting areas that should be dented or damaged.
The Dents weightmap
You can see here why I decided to subdivide those particular parts of the mesh.
That's all you need to do in modeller. The next stage is the surfacing in Layout. If you want to download the model at this stage of the tutorial (i.e. without surfacing), use the link below.
Creating the scene
An important consideration when surfacing an object is setting up the lighting and environment so you can get the best feedback about the changes you are making. After all, what's the point in changing the reflectivity if there's nothing to reflect? When setting up the lighting you should try to have the following:
- Provides main diffuse lighting. Preferably set at an angle to give varied
lighting across the different surface directions. Try to leave one face dark, as this will help show reflectivity
- Very bright light from behind. Highlights the edges of the object and helps to show up the bump channel
- Try using a few point lights close to the surface to help show specularity
- Turn it off! This does nothing for you. It will hide the reflectivity in darker
areas, and any subtle changes that you make will be difficult to see.
It's also a good idea to have an object for your subject to reflect. I tend to use a luminous white half sphere to mimic a bright sky (with the "Hidden From Camera" option selected), but what you use is up to you.
You can download the scene below. The lighting is set to work with the anvil object downloaded from the previous page.
I usually find that the bump channel is the best channel to start with. If you start with the colour channel, it can make it difficult to see what effect your adjustments on other channels are having. A good point to note is to make sure Anti-Aliasing is turned on when making your adjustments, as it makes a huge difference to the final appearance of the bump.
I said at the beginning of the tutorial that I wouldn't take you through too much detail of the surface parameters. The exception to this is the Bump channel, as I'll be introducing you to the concepts. For the other channels, I'll give you a view of the overall strategy, and then you can make up your own mind with regards to the aesthetics.
For the bump channel I used three components: a Crumple procedural for the main bump (removed from where the "Smooth" weightmap exists), a Hetero Terrain procedural for dents (specified by the "Dents" weightmap), and a Veins procedural. You can see each of these as it is applied in turn below (note that Diffuse has been temporarily reduced to 40% to prevent the lights from burning out the surface, and shadowing has been turned off)
Notice in the first picture how the Crumple procedural is not present where the "Smooth" weightmap is defined. The second picture is the other way round; the Hetero Terrain procedural is present where the "Dents" weightmap is defined. In the third picture, the Veins texture is very subtle but it is there! It helps to give the impression of grooves in the surface.