Exploring the world of free tools for GIS, GPS, Google Earth, neogeography, and more.
Frank over at Google Earth Blog was nice enough to link to my post last week about GE-Graph. In his post, he describes another great Google Earth utility from the same author that I was also planning to post on, and here it finally is.
Continue reading ‘Drawing Grids, Paths And Polygons In Google Earth Using GE-Path’
Via Ogle Earth, a new way for two people to share and show positions in Google Earth, GE Sharing. Unlike Unype, which requires a Windows-only download, this uses a shared network link, making it cross-platform. Site is in German, but if you click on the “Los geht’s!” (“Let’s go!”) button, and follow Stefan’s English description at Ogle Earth, it should be pretty straightforward.
Addendum: Here’s the link to the English version of the page.
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.
Continue reading ‘Thematic Polygon Shapefile Display In Google Maps’
A reader from Canada asks, “Is it possible to load an AutoCAD file (dxf?) into my Garmin GPSMAP 60csx?”. I don’t know of a free one-step solution, and if any reader knows of one, I’d appreciate. However, using some of the procedures described in previous posts on this blog, it can be done fairly easily.
1. Convert the DXF file to a shapefile using the MapWindow DXF To Shape Converter. Points, lines and areas will have to be converted into separate shapefiles.2. If the coordinates of the DXF are not in the native coordinate system for most GPS units (latitude/longitude, WGS84), you’ll need to re-project the new shapefiles from their current coordinate system (e.g. UTM) to the GPS native system using MapWindow.
3. Load the shapefile into the GPS using one of several programs available. Points and lines will be imported as waypoints and tracks, respectively, while areas will be imported as tracks that describe the perimeter of the area.
It’s even less painful than it sounds; should take no more than about five minutes to put a DXF file into a GPS, once you have all the software you need installed.
Addendum: You would also follow the same basic procedure if you wanted to display a DXF file in Google Earth, but instead of step 3 above, you would convert the shapefile created in step 2 into a Google Earth KML file using one of the converters I’ve posted about previously.
In addition to the standard image overlays of Map, Satellite and Hybrid for Google Maps, the Active Trails website has an additional overlay button – Topo, for topographic maps. At lower zoom levels, the 1:100K scale USGS topo maps are visible, but if you zoom in close enough, the larger-scale 1:24K maps become visible. Comparing Map, Satellite and Topo overlays, there appears to be a good position match between the three. Active Trails also has placemarks for many kinds of outdoor trails across the country (hiking, biking, equestrian, etc.) entered by site users. You can also install a network link in Google Earth that will let you view the trails there, similar in nature to the new Google Earth layer from Trimble.
Addendum: Fixed the Active Trails links (sorry about that). In the comments, MH points out the ACME Mapper 2.0 site, which is a better choice. It displays black-and-white USGS aerial photos, and also lets you print out a copy of the on-screen map with the push of a button.
If you were wondering how I created the Google Earth rainfall plot in yesterday’s post on FAO climate data, I didn’t use one of the shapefile to KML converters I’ve posted about. Instead, I used a free program called GE-Graph that takes tabular data and lets you plot it in colors and polygons that depend on the value you’re plotting.
Continue reading ‘Plotting Data In Google Earth Using GE-Graph’
Via OgleEarth, a relatively new blog called Census KML Data Visualization has been posting visualizations of US Census data in Google Earth, with links to the KML files. Newer posts have branched out to visualizing campaign contributions by congressional district and time. Nice stuff, and a good complement to the gCensus site.
After being unofficially open for several weeks, Matt Fox’s Google Earth Library is now fully open and operational. Many useful and interesting sets of placemarks and tiled overlays, covering topo maps, aerial photos, aviation, weather, geology, solar system objects, global warming, etc., with more added every day. Add this one to your bookmarks/RSS feeds.