Creating a Terrain Object

The Terrain object is a great object that enables you to create terrains from splines representing elevation contours. These contour splines can be created in Max or imported using a format like AutoCAD's DWG. If the splines are created in Max, make sure that they are attached to each other as one object, in the order in which they will eventually be attached. The splines all must be closed splines.

To create a terrain, create splines at varying elevations, select all the splines, and click the Terrain button. You can use the Pick Operand button in the Pick Operand rollout to select additional splines to add to the Terrain object. All splines in the object become operands and are displayed in the Operands list.

The Form group includes three options that determine how the terrain is formed: Graded Surface, Graded Solid, and Layered Solid. The Graded Surface option displays a surface grid over the contour splines; the Graded Solid adds a bottom to the object; and the Layered Solid displays each contour as a flat, terraced area. The Stitch Border option causes polygons to be created to close open splines by creating a single edge that closes the spline. The Retriangulate option optimizes how the polygons are divided to better represent the contours.

The Display group includes options to display the Terrain mesh, the Contour lines, or Both. You can also specify how you want to update the terrain.

The Simplification rollout lets you alter the resolution of the terrain by selecting how many vertical and horizontal points and lines to use. Options include using all points (no simplification), half of the points, a quarter of the points, twice the points, or four times the points.

Coloring elevations

The Color by Elevation rollout, shown in Figure 18.8, displays as reference the Maximum and Minimum Elevations. Between these is a Reference Elevation value, which is the location where the landmass meets the water. Entering a Reference Elevation and clicking the Create Defaults button automatically creates several separate color zones. You can add, modify, or delete zones using the Add, Modify, or Delete Zone buttons.

Figure 18.8: The Color by Elevation rollout lets you change the color for different elevations

You can access each color zone from a list. To change a zone's color, select it and click the color swatch. You can set colors to Blend to the Color Above or to be Solid to Top of Zone.

Tutorial: Creating an island with the Terrain compound object

In this tutorial, we create a simple island. The Color by Elevation rollout makes distinguishing the water from the land easy.

To create an island using the Terrain object, follow these steps:

1. Select Create Shapes Ellipse, and drag in the Top view to create several ellipses of various sizes representing the contours of the island.

   The first ellipse you create should be the largest, and they should get progressively smaller.

2. In the Left view, select and move the ellipses up and down so that the largest one is on the bottom and the smallest one is on top. You can create two smaller hills by including two ellipses at the same level.

3. Use the Edit Select All (Ctrl+A) menu command to select all the ellipses, and select Create Compound Terrain.

   The ellipses automatically join together. Joining all the ellipses forms the island.

4. In the Color by Elevation rollout, select a Reference Elevation of 5 and click the Create Defaults button.

   This automatically creates color zones for the island. The elevation values for each zone are displayed in a list within the Color by Elevation rollout. Selecting an elevation value in the list displays its color in the color swatch.

5. Select each elevation value individually, and set all Zones to Blend to the Color Above option for all zones, except for the Zone with the lightest blue.

   This creates a distinct break between the sea and the land of the island.

Figure 18.9 shows the final terrain. In an example later in this chapter, we use the Scatter compound object to add trees to the small terrain island.

Figure 18.9: A Terrain island created with the Terrain compound object