Elevation Grid
Exercise

Description

In this exercise you will create a shape using an ElevationGrid node from scratch. Later you will modify the ElevationGrid to add per-vertex colors.

In visualization, real and mathematical surfaces are often computed on a 2D regular grid. Calculated values are mapped to heights above the grid, creating mathematical Elevation Grid. Similarly, Elevation Grid surfaces can be created using real-world elevation information for parts of the Earth.

This exercise focuses upon use of ElevationGrid and Color nodes.

VRML Concepts

This exercise requires you to understand and make use of the following VRML features and concepts:
• Basics
  • VRML file structure
  • Comments
• Shapes and appearance
  • Shape node
  • Appearance node
  • Material node
  • ElevationGrid node
  • Color node

Files

Since you are creating your own VRML file from scratch, no files are needed to get started with this exercise.

Tasks

1. Create a VRML file called "elevgrd1.wrl" which contains an ElevationGrid Shape that conforms to the following specifications:
   • Use a Material node to color the shape.
     (A nice diffuse color is 0.2 0.2 1.0)

   • Use the following height values:
     
     0.0, 0.0, 0.0, 0.0,
     0.0, 0.2, 0.1, 0.0,
     0.0, 1.0, -0.5, 0.0,
     0.0, 0.0, 0.0, 0.0,

     HINT: Notice that there are 4 values in the x dimension and 4 values in the z dimension.

   HINT: Use a 1.0 spacing in both x and z dimensions.

   HINT: To enable VRML to draw both sides of the ElevationGrid, specify a "solid FALSE" field and value.

   SOLUTION: elevgrd1.wrl

   ---

2. Copy the file "elevgrd1.wrl" to "elevgrd2.wrl", then add a Color node to the ElevationGrid to override the Material node.

   Use the following color values:
   

   0.2 0.2 1.0, 0.2 0.2 1.0, 0.2 0.2 1.0, 0.2 0.2 1.0,
   0.2 0.2 1.0, 1.0 0.0 0.0, 0.0 1.0 0.0, 0.2 0.2 1.0,
   0.2 0.2 1.0, 0.0 1.0 1.0, 1.0 1.0 0.0, 0.2 0.2 1.0,
   0.2 0.2 1.0, 0.2 0.2 1.0, 0.2 0.2 1.0, 0.2 0.2 1.0,

   SOLUTION: elevgrd2.wrl