Defining a Map from a Graphics Image

Overview
GenesisII can generate a surface directly from a graphics file. This is useful as some surface data is available in this format, and it can also be used for creating surfaces from non-landscape sources, such as pictures of the Mandlebrot set.

The graphics file must be in bmp format. If your file is in a different format is can easily be converted using a utility such as Paintshop Pro. GenesisII creates a map of the same dimensions as the graphics file, mapping each pixel to a grid point.

Each pixel in the graphics file logically consists of three numbers representing the red, green and blue components of the pixel, each of which can be any value from 0 to 255. GenesisII combines these values to calculate a single number, which it then converts to a height.

The three colour components can be combined in any one of six different ways depending on the order in which the components are processed. For example if and order of Red, Green, Blue is selected then the number is calculated as

(Red-value * 256 * 256) + (Green * 256) + (Blue).

To convert this to a height GenesisII takes this as a fraction of the maximum value and multiplies this by the value entered for the maximum height in the graphics import dialog.

Importing a Graphics file

1. Select Importà from the Tools menu.
2. When the read file dialog is displayed choose Graphics file (bmp) as the file type, select a bmp file to import, and click OK. The Graphics file import dialog is displayed.
3. Set a maximum height value and choose an order for colour components processing from the set of six radio buttons. You will also need to specify a grid point spacing (nominally) in metres. Press ok to start the import.