Thoughts - Damn Voids!
Rapa Island - ISS Image ISS004-E-12979
I have worked on this Rapa Island project off and on for a number of months. It is a challenge because: 1) It is a high island and that means contours. Up until a month ago, I had not figured out how to easily plot contours. Using SRTM imagery and Global Mapper, it is a relatively simple task. 2) Clouds! Now that is a major problem when digitizing from a cloud obscured image. Your work is typically one guess to another guess or you are forced to scrounge whatever imagery you can gather to fill in those cloudy blanks.
Rapa Island - SRTM Image With Voids
Those sheer walls that show up in the above image are cloud obscured areas. The shuttle mission that compiled these SRTM files couldn't gather elevation data through clouds. Some folks are systematically, doing their best, to fill in the voids. Progress is slow and with mixed results. The real champions of the void fillers are the flight simulator people. They are trying to construct their 3D world to fly over.
Rapa Island - Shuttle Image 3D With VoidsSo this is what one gets when you drape an image over the SRTM data with voids. Peaks peak and valleys valley. Everything looks as it should. Everything, that is, except those damn voids!
view Eiao Island on Google Maps
Enjoy!
Labels: 3D, Global Mapper, SRTM, voids
