3/24/2011 2010 Census Tracts in Google Earth

There are a number of ways to get MapInfo .tab files (and Esri .shp files) into .kml format, for display in Google Earth. Having said that, I feel that it is a "Best Practice" (if you have the native software program - MapInfo for .tab files) to work in the native program as much as possible. MapInfo offers Google Earth Link, which is "a MapBasic application that automates the export of vector and raster maps created in MapInfo Professional to the Google Earth application."



Unfortunately, even now in 2011, the size of these files can get pretty big, and things can move pretty slowly (zooming in-and-out, panning around the map). The AZ_2010_Census_tracts_2011_3_24_13_06.KML file is 28.6 MB (built from 5.35 MB in MapInfo files); the MapInfo files for California are 19.1 MB, but they explode to 113 MB as a Google Earth kml file.

The files need to be thinned. MapInfo has an operation that specifically thins a file:


I recommend specifing Thinning for 3-Node Collinear Deviation and Node Separation of only 10 meters. This pair shows the blue nodes in Census Tract 2051.20, before and after thinning:



The resulting thinned files still follow streets, which is the ultimate test in Google Earth. The thinned California kml file is 25.9 MB, a reduction of 87%. This reduction makes everything run smoother, with no sacrifice in visual integrity.

The link to the thinned 2010 Census Tracts for Google Earth:
http://www.dixonspatialconsulting.com/kml_files.html

Help yourself!