Tarsier: Raster data

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 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

You can do basic manipulations and analyses of raster data using operations in the Raster drop down menu. To access this menu, a raster viewer window must be active (selected). Selected operations will then only apply to the active raster.

For more advanced manipulations and analyses you can use various tools, analysts, or models (see below).

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

Take the Tarsier tutorial for Raster data.