JS writes, “I am doing a very small wireless operation in Catalonia, and it would be very interesting to have the coverage map of the antennas. Do you know any free (or cheap) tools to do that and place it on Google Earth?” I know of two free Windows tools useful in analyzing radio coverage. The first one is a general purpose terrain analysis program that will give “quick and dirty” plots of line-of-sight coverage and required antenna heights fairly easily. The second, more sophisticated program is specifically designed for determining broadcast coverage and signal strengths, but is also more difficult to use. Getting the data products into Google Earth can take some work, but can be done.
Archive for the 'MapWindow' Category Page 2 of 3
In a previous post, MicroDEM was used to create viewsheds from a DEM (digital elevation model), and plot them on top of either a DEM terrain image or a corresponding map loaded into the program. But it could be useful to export the viewshed data alone, either in raster or shapefile vector format, for use in other GIS programs. More generally, the need might arise to convert a general raster image of an area into a polygon shapefile. You can do this with the Spatial Analyst extension for ArcGIS, but the two together are pretty expensive. There’s a somewhat painless way to do it with free software.
There are a number of free ways to convert shapefiles to KML format for display in Google Earth, but fewer and less flexible shapefile display options for Google Maps. This site lets you upload small line and polygon shapefiles for display in Google Maps, but not in a permanent form, and with limited display options. This other site details a procedure to display polygon shapefiles in Google Maps, but it’s not particularly straightforward to implement. There’s also some direct support for displaying simple KML files in Google Maps, so you could always try converting the shapefiles to KML and then opening them in Google Maps. But there’s a Java application that makes the process reasonably straightforward for polygon shapefiles, shows the data already loaded in a Google Maps interface, and offers some added display options.
Yesterday’s post dealt with converting point shapefiles to a text format compatible with spreadsheets. Today’s post handles the opposite – converting spreadsheet data to point shapefile format.
In the last post, I covered a mildly painful way to convert the vector data (points, paths, and polygons) in Google Earth KML files to shapefile format, while keeping at least the name associated with the points and paths. Today, I’ll describe a simpler and faster two-step process, but one that unfortunately doesn’t keep the name or any of the other KML data associated with the original shapes.
No new content – just a consolidated listing of the posts in this series.
Description of basic shapefile viewing, and modifying views using attribute data.
Opening, querying, editing, and otherwise modifying shapefile attribute tables.
Creating shapefile layers, adding shapes, modifying shapes, and adding attributes.
Advanced shapefile manipulation, including merging, erasing, clipping, selection by mask, and buffering.
Using MapWindow to re-project shapefiles into different coordinate systems and datums.
This is the final installment in my screencast series on MapWindow GIS. In addition to an easy-to-use shapefile editor, MapWindow has some advanced tools for combining, manipulating, and selecting from shapefile layers that aren’t all that common in freeware GIS software.
Third in the MapWindow screencast series is a quick runthrough of MapWindow’s shapefile editing capabilities. I think it’s one of the easiest to use of all the freeware GIS programs I’ve seen.