With TdhGIS, you can:

• Create thiessen and buffer polygons from points.

• Allocate point data to polygons.

• Allocate polygon data to other polygons.

• Color polygons based on user data using either discrete intervals or gradients.

• Create contour lines and polygons.

• Intersect, merge, and subtract sets of polygons.

• Determine the area and perimeter of polygons, including exclusion polygons (i.e. holes).

• Import and export shape files.

With TdhGISnet, you can:

• Perform shortest path analysis for any number of intermediate destinations.

• Import OpenStreetMap data by specifying way tags (e.g. select roads, walkways, rails or any other way data in OSM).

• Add nodes anywhere, permanently or temporarily, by clicking or specifying coordinates.

• Edit data, display results graphically and produce reports usable within spreadsheets or database managers.

With either program, you can:

• Use raster images as background.

• Transform coordinates based on the Proj4 library. (e.g. convert from longitude-latitude to cartesian coordinates.

TdhGIS and TdhGISnet are free software, run on Linux and MS Windows and can be downloaded at TdhGIS.com