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The selection textures and displacement maps are created before all other operations. We only need to make them once; they will serve for all the following projects. Of course, they can be shared on the web so that the job isn’t done a hundred times.

### 1.1 Textures for selection Mostly, the objects which cast a shadow are trees and buildings. Inside a forest zone, trees are closely grouped, so it’s at the borders of the forest or inside clearings that we can observe cast shadows. We will need to know which parts of one particular texture casts a shadow. This is the purpose of the textures used for selection map. For each forest and urban texture used in a particular TerraScene project, we have to create the corresponding texture for selection. Select carefully on the original texture each part that will be bumped up. ##### Tips for urban textures: Select the lightest shades. For manual work, switch to quick mask. Use the “facet” filter to eliminate some noise and get square houses. Erase the streets and parkings lots, paint the buildings which are not selected. Residential parts with many trees can be defined as a single object. The level of detail is your choice. It’s a long work, so limit the number of texture types you will use for rendering. SAVE SELECTION as a new channel. Create a new document exactly the same size as the original texture. LOAD SELECTION from the first document. Fill the selection with a specific pure colour. You may want to fill the remaining parts (clearings, streets) with another colour, in case they would need some interventions later in the process. Else, keep them white. Save your textures as .jpg to a new folder inside the TerraScene texture folder. Suggestion : Give the same name as the original texture, with the letters “SEL” before. Ex: Suburb-usa.jpg becomes SELsuburb-usa.jpg Here are some samples for the standard TerraScene textures : Cool-conifer-forest.jpg and City-heavy-usa.jpg. NOTE : The unselected parts have been filled with deeper color. The textures need some work yet - some streets were selected because of their light shade and must be deselected.
Texture | Texture for selection
One more example with Suburb-usa.jpg (larger scale). Here you can see some trees and some grouped residential houses as well as individual buildings. NOTE : I used different colors for each urban map, because I want the “City-heavy-usa” buildings to cast longer shadows : thus I need to select them separately. However, if you don’t use the advanced advices below (part 5), only one colour is needed.