C-47 WIP (2)

Painted Shadows and Highlights
Shadows and highlights on objects help them to look more realistic since real objects in the real world generate them as a function of being lit. However, shadows and highlights move across the surface of an object as that object moves through its environment. If these details are burned-in to the texture, they become fixed artifacts on the surface and therefore look wrong when the object moves (or spins/rotates) in a lit environment. Additionally, since the rendering engine automatically generates shadows, if they exist both in the texture and as a function of being lit in the rendering engine, there are two sets of shadows and highlights on an object; one set which moves as expected and another which does not.

Using captured images directly for textures can lead to the inclusion of shadows and highlights as burned-in artifacts in those images. In order to avoid the discontinuity this situation will create, they might need to be removed by hand and this can be difficult and time-consuming. When using captured source images to make textures from, try to think about these artifacts and how they will make the object look when it moves. By the same token, some care could be taken when painting shadows and highlights into textures by hand. It is recommended that the painter make an effort to reduce the strength and definition of painted shadows and highlights.

Including some painted shadows and highlights is certainly advisable since it gives an object a more realistic appearance especially when it is sitting still in its environment. Painting highlights and shadows on separate layers is one of the best methods for controlling how they end up interacting with the finished texture. Opacity and blurring levels can be changed independently and if the layers are set to blend with the rest of the texture (such as setting the blending mode of highlight layers to Dodge or Lighten and the shadow layers to Multiply or Darken) the effect these layers have on the rest of the texture can be modified in extremely subtle and effective ways.

Shadows and highlights may not be burned-in to photographic (or otherwise captured) source if the correct lighting is present when the images were originally captured. Directional lighting (from specific sources such as the sun, or artificial lights) is the main culprit here. Burned-in shadows and highlights will usually be considerably moderated if directional lighting is minimized when the source images are recorded. If the images in question are recorded under mostly ambient lighting conditions (such as overcast days) the effect of burned-in shadows and highlights is greatly reduced. It is of course, very difficult to arrange perfect lighting conditions and this almost by itself is a compelling enough argument for painting textures from scratch.