Vector Based Spatial Analysis

Easy and FREE, for MS Windows and Linux

(You can be up and running within minutes!)

Feature Summary:

  • Graphically create and edit geometric data, as with a CAD program
  • Import Shapefiles and OpenStreetMap data
  • Use raster images as background and a CAD drawing as an overlay
  • Transform coordinates based on the Proj4 library.
  • Color polygons based on user data values using either discrete intervals or gradients
  • Allocate point data to user specified buffers for points, polygons and multilines (e.g. find all gas stations within 1 mile of a highway)
  • Allocate point data to polygons. (e.g. assign structures to hydrological basins)
  • Allocate polygon data to other polygons. (e.g. allocate population data by census block to political boundaries)
  • Create thiessen polygons (e.g. for all hospitals within a state, define the areas closest to each hospital)
  • Create data contours (e.g. create lines of equal ground elevation based on a set of elevation points)
  • Create contour polygons (e.g. define the area where average rainfall exceeds a selected value based on weather station data)
  • Calculate the area and perimeter of irregular polygons, including exclusion polygons (i.e. holes)
  • Data is stored in an open database allowing manipulation by other software

Even if you don't yet need these easy to use spatial analysis operations, TdhGIS makes a very good Shapefile viewer and editor!

About the Author

Tim Hirrel (

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