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 its 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. Its 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

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Texture for selection

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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 dont use the advanced advices below (part 5), only
one colour is needed.

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