Musandam Peninsula OM - 50-Meters Contours Using Plans One Through Four

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!

Isla del Coco CS - Treasure Island

Isla del Coco

1) The first image is DigitalGlobe's (DG) coverage found in Google Earth (GE). Using GEs Path Tool, I digitized over 3/4 of the islands shoreline. The digitized shoreline from a DG image is considered to be EEVS precision, meaning scales below 1:12,500 is routinely possible. Once I had completed my GE phase of this project, I saved the completed EEVS shoreline with cloud-obscured gaps identified for later work. I was able to then load this KMZ file into Global Mapper (GM)

2) The balance of the shoreline was digitized using WRS imagery, specifically those identified as path 016 row 056. The imagery is packaged in 257MB TAR files. Once downloaded and unzipped, one can select from a number of TIFF images. I used nn40 tif image.

3) With the shoreline complete, I systematically added layers of information (name labels, land polygon, streams, contours). The SRTM image, N05 W088, served a double purpose. First, I was able to use GMs "Generate Contours" routine to create contours. In addition, The SRTM image was used to create a shaded relief image of Isla del Coco.

Isla del Coco - Island Image Georectified JPG

Now for some data for all of you with mapping packages. I have zipped 9-layers of data that makes up the vector files for this project. The layers include: shoreline, streams, contours, name labels. Using GM, the zipped shapefiles load in about 2-seconds.

Isla del Coco - Vector Shapefiles

The second package contains a georectified JPG imag of the island and a DEM formatted file of the island. It should be loaded first with the JPG draped over it. You can do some neat 3D work with this combination of images.

Isla del Coco - Georectified JPG and DEM Files

Isla del Coco - 3D View SW to NE

If you load it with various vector layers, you can see them draped over the landscape of Isla del Coco.

Now for the "Treasure Island" stuff. According to Wikipedia, there are at least 3 treasures buried on this island. Pirates used the island as a hideout for years. Supposedly, Robert Louis Stevenson used Isla del Coco as inspiration for Long John Silver's Treasure Island.

Enjoy!