Free Geography Tools

If you have a set of data points randomly distributed in space, and want to create a basic grid of evenly-spaced set of data points derived from this data (nothing fancy, like curve fitting or Kriging), QuikGrid is blazingly fast at this task. For example, here’s a evenly-spaced set of 625 elevation points (25 x 25) downloaded using the Zonums Terrain app, loaded into QuikGrid and displayed as a set of contours, and coloring representing different heights:

For the same area, I also downloaded a set of 625 randomly-selected points, which QuikGrid can automatically grid, contour, and display in a similar fashion, essentially instantaneously:

In some areas, the spacing between random points is too great for QuikGrid’s default distance cutoff tolerance, and it fills in those blanks with data values of zero. But by adjusting the tolerance, it’s possible to fill in some of those gaps:

Some gaps on the edges, where it has trouble filling in the remaining gaps. Comparing this contour image to the evenly-gridded surface at the top, there are some differences, especially in locations where values changes rapidly. But for a basic approximation, it’s not bad, and offers a quick-and-dirty alternative to more complicated gridding processes.

QuikGrid can also visualize grids in 3-dimensions as well:

Import formats supported by QuikGrid include data triplets with a variety of acceptable inputs for position, including variations on lat/long in degrees/minutes/seconds. If you have decimal lat/long, use the “Input metric data points” option, but be aware that the y-value will be longitude, and the x-value latitude, as in the examples above. It also accepts data point input in DXF and Submetrix format, as well as grid input in ER Mapper Raster, USGS 1-degree DEMs (aka 1:250K DEMs) and QuikGrid’s own grid format. Generated grids can be saved as xyz triplets, Surfer, QuikGrid and ER Mapper formats; you can also export contours and grids in DXF format, and grid surfaces in VRML. There are many other features, including a scripting language, and various display and labeling options.

The helpfile is comprehensive, and well-done, and includes instructions on running the program in Linux under the Wine emulator. The C++ source code is also available, released under the Gnu GPL.