A Better Overlay

I’m currently working on a 3D flyover for a client, inevitably I do this task in Google Earth, but there are many things I don’t like about how the software functions, so, I’ve created some cartographic patches to make it more tolerable to view.  Touring from one point to the next or down a path are very smooth, and that’s my main reason for using GE, so I’ve taken full advantage of that.  But from there, I’ve tried to customize the rest.  The first patch to take care of was the imagery.  Google’s source has a huge cloud over the property, so I brought in a tiled NAIP overlay.  The resolution isn’t terribly high, but that’s not necessary for the altitude of our flyover.


The second issue I had to deal with was showing protected lands polygons surrounding the focus property.  A simple polygon overlay in GE produces pretty dismal results, as there are no applied shadows to show shaded relief and the property boundaries blur and become completely distracting at oblique views.  So, my trick here was to build the protected lands polygons into the imagery tiles using ArcMap.  I brought in NAIP imagery on the bottom, followed by the polygons, overlayed by an 85% transparent hillshade, but only showing the hillshade where it overlapped the polygons using Advanced Drawing Options in ArcMap.  I didn’t want to double-up the shadows, and this little tool worked great.  If you wanted to have some sense of the imagery on the protected lands as well, you could add a second layer of NAIP just below the hillshade and set that to 60%-70% transparent.



One Response to “A Better Overlay”

  1. Brian Timoney Says:

    Filled vector polygons are one of the most taxing things you can do in Google Earth and folks with marginal graphics cards may very well crater all together.

    We’ve had good success with streaming the outline and centroid as vector (for rollover effects and balloon clickability) and streaming the poly fill as tiles.


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