Difference between revisions of "Tarsier: Raster data"

Revision as of 11:49, 28 February 2009

As the name implies, a Tarsier Raster Data file (.tra) is Tarsier's gridded data format. It is made up of two parts: 1) an ASCII header file that specifies the structure of the grid and data properties, and 2) a series of data values stored as binary numbers.

A typical Tarsier header looks like:

 Cols         25
 Rows         25
 XLLCorner     0
 YLLCorner     0
 CellWidth      1
 CellHeight      1
 NoDataValue  -9999.000000
 Projection  latlon
 Precision  float
 Format  binary
 *                

This raster is a 25 X 25 pixel lat/long grid with the lower left corner located at the intersection of the prime meridian and the equator. The resolution is 1 degree. Data points are stored as floating point numbers (can include signed decimals) and the value -9999 represents no data.

The size of the raster is limited by the memory of your machine, but most modern computers can easily handle raster up to 49,000,000 pixles (7,000 x 7,000).

Tarsino has a peculiar fondness for UTM grids, but other projections are also supported:

-add table of projections-

The following precisions are available:

-add table of precissions-

Working with Raster Data

Learn more about rasters and how to work with .tra files

Take the Tarsier tutorial for Raster data.