Please help me with a Google Earth overlay

Miscellaneous and Personal Stuff I Must Share
1

I’m trying to make some Google Earth overlays of Russian provinces. I keep getting messed up by the distortion imposed by the map projection closer to the pole.

I would be greatly obliged if someone could make a solid red overlay that covers the Sakha Republic and matches up with its border, and send it to me.

What I’ve been doing before which worked farther south was to view the area in google earth, take a screen shot, use photoshop to cut around the area I want and fill it with the proper color. Then I saved this as a PNG and imported it into GE. Any advice would be appreciated.

2

If you want to use an image overlay, you need to find a source map that uses the appropriate projection; I believe that this (“cylindrical equidistant” projection) is the one you want. These are somewhat difficult to find at high resolutions; you could, however, make one from a Mercator or other cylindrical projection without too much trouble, just by variably squashing the map near the pole so that the latitude lines are all equally spaced (unlike a Mercator projection, where the parallels get farther away as you approach the poles).

Alternately, if you can get GIS boundary data for the area of interest and all you want is a simple color shading, you can use a KML Polygon instead. This is probably a nicer way to go if you can find the data.

3

I’m not sure where you’ve gotten with this. I undistorted this time-zone map in Miller cylindrical projection, for which some of the boundaries coincide with those of Sakha, into an equirectangular projection, and chopped out northeast Asia, to give this image. (Unfortunately, this only gives part of the boundary; you’d have to freehand the southern boundary. I couldn’t find any public, recent, high-resolution maps of the area.)

Use with this kml file to give an overlay of the desired region (download the image and save it locally, of course).


<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.1">
<GroundOverlay>
   <name>northeast Asia overlay.kml</name>
   <color>7fffffff</color>
   <drawOrder>1</drawOrder>
   <Icon>
      <href>http://img528.imageshack.us/img528/4043/neabigup4.jpg</href>
      <refreshMode>onInterval</refreshMode>
      <refreshInterval>86400</refreshInterval>
      <viewBoundScale>0.75</viewBoundScale>
   </Icon>
   <LatLonBox>
       <north>80</north>
      <south>45</south>
      <west>70.03</west>
      <east>169.87</east>
  </LatLonBox>
</GroundOverlay>
</kml>

The image is fairly low-resolution (I didn’t find any good public GIS data of the area in a quick search) but you might be able to doctor it up.

4

Thanks for the help. I got the image to fit fine. I also figured out that I can use Curious World Maps in cylindrical display mode to create these types of overlays quickly.

5

Ah, good, that sounds like a much better map source than random Google image-search results.