Musandam Peninsula - EVS Precision Map (1-175,000)
I posted the above map of the Musandam Peninsula a few weeks ago. The geography is fascinating. However, I knew more work had to be done to complete my map. Specifically, I wanted to create contours to overlay onto the area.
My first attempt, Plan One, was straightforward - download the SRTM HGT file, load it into Global Mapper, generate contours and I would be finished . . . Whoops! Not so. It turns out that the SRTM HGT file for this area is full of voids, those nasty little holes of nothing. With voids my generated contours were grossly inaccurate.
I've been at this mapping business long enough to know that if one source doesn't work, there is most probably another, like Plan Two - the CGIAR-CSI SRTMs. These are void filled versions of the HGTs. I downloaded the appropriate SRTM tile, loaded it, generated contours and . . . Whoops! Not quite right.
Still not to be deterred, I went to Plan Three - using a void-filling piece of software called Void Killer 2 I tacked the contour generating problem once more. I am aware of a number of freeware SRTM void fillers, but I wanted to try the trial version of VK. I downloaded the trial copy, unzipped it and loaded the requisite SRTMs . . . Whoops! Won't let me make a copy and I didn't want to spend $43 to test it's claim as the best void filling software.
Musandam Peninsula - EVS Precision Map with 50-Meter Contour Intervals (1-175,000)
Plan Four to the rescue. In order to use Void Killer 2, it was necessary to convert the CGIAR-CIS SRTM tile from TIFF into DEM format. I loaded this DEM tile on top of the void peppered HGT file and generated contours . . . voila! It worked. Somehow the combination of the two sandwiched together allowed GM to generate contours without voids. Some of the 50-meter contours spill across water versus land, but that can be cleaned up. The HGT voids were filled with reasonable contours. The combination of SRTM HGT and SRTM DEM did the trick.
I would caution the state of Oman - Gentlemen, don't embark upon a multi-million petro-dollar project based upon these contours. However, I am confident that GM's contour generating algorithm is sound for the intrepid Omani backpacker, who could rely on these contours with a fair level of confidence.
Enjoy!
