Comparison - EVS to GE Georectification
EVS Image with NGA PGS Shorelines Superimposed
As I worked on my previous post, Thoughts - Antipode of Qibla at Mecca, I asked myself once again "How does Google Earth image georectification compare with Landsat ETM+ 2000 image or with NGA PGS Shoreline data?" So let's compare. The above is my EVS Shoreline map which was constructed using Landsat ETM+ 2000 imagery. I have marked a point on one of the northern motus with coordinates (decimal). I have superimposed NGA PGS shorelines (in red) to show that they are very close to EVS precision.
GE Image with EVS Lat/Lon Compared to GE Lat/Lon
At this scale, approximately 1:25,000, the EVS Lat/Lon rests nearly atop the GE Lat/Lon. At this resolution, EVS and GE seems to work together. Now let's zoom so that we can see any difference between the points and then measure that difference.
EVS Lat/Lon Compared to GE Lat/Lon
The same point determined on two different images is only 12.33-meters apart. Using satellite imagery to snap a picture of moving earth and have a 12.33-meter wobble is doing very good. That is unless you are going to build a house near the shore of this motu and it turns out your property is 12.33-meters from the shore and your house is now a houseboat. Now that would be a problem.
Seriously, a 12.33-meter difference at the useful scale of these images is excellent.
Enjoy!
