Last Updated November 9, 2011

Creating a Terrain using a Height Map

Introduction

You can create a terrain mesh using a heightmap.

The terrain is created by using a regular grid of points laid on the x-z plane. The x & z coordinates of this grid follow a regular pattern like the vertices of a chess board. The y-coord from each point is taken from a heightmap. The heightmap is an image file, each pixel in the image represents one of the points on our grid. The height of the point (y-coord) is represented by the colour of the pixel. Below is a height map of one of the Hawaiian Islands. The bright areas represent high ground.

Grey-scale height map

The height map is loaded as an image (texture)and the pixel data used to modulate vertex coordinates .

Wireframe terrain

Normals

In order for this terrain to be correctly rendered with lighting, each vertex needs a normal. A normal for a vertex is found by averaging the normals for the neighbouring triangles.

Texture

To add realisim we can add a texture to the terrain (this will usually be a different texture to the height map). In this case I have created a texture which will show the zero height areas as blue (sea), low-lying areas as yellow (beach), and mountain tops as white (snow). This texture need to be correctly aligned in order to work. (The texture was created from the original heightmap + some simple photoshop manipulation)

Terrain texture