I recently received a request for a map of the Central Biferno Valley area of Molise province, Italy. In general, getting cartographic data for areas outside of the United States can be quite difficult. Foreign countries do not usually make such data available to the public, especially not for free. Ironically, the best source of the kind of data needed to make DEMs of countries outside of the U.S. are various United States government agencies. The United States seems to be the only country that considers its mapping database basically public property.

In this case the NGA Raster Roam provided the information necessary to construct a map. The DTED Level 0 database provides 30 arc-second (approximately 1km) post spacing of elevation data points, which is very coarse resolution compared to that available from the USGS for the United States. NIMA also controls the databases for DTED level 1 (100m spacing) through Level 5 (1m spacing (!)). Unfortunately, only Level 0 data is available to the public. For some reason NIMA feels that release of its 100m DTED 1 data would compromise national security, despite the fact that the USGS provides 30m elevation data for the entire United States! Even more strange is NASA's plan to release what amounts to Level 1 data through its SRTM radar mapping program. Talk about turf stomping. There must be a lot going on behind the scenes here because, the promised "early 2001" initial data release has not happened as of 1 June 2001.

Anyway, I used what I had to construct a map of central Italy that contained the area of interest. To do so I merged nine individual DTED 0 quads to make one large map. Each quad covers an area of 1 degree longitude by 1 degree of latitude. I selected, downloaded, and unzipped the map area from the NIMA website. I did the merge the easy way, using the utility in MicroDEM to combine the separate files into a single 361 X 361 BMP file. The importation and merging worked flawlessly.

I then imported the BMP into Paintshop Pro and created a solid tan overlay image by flood filling the base image. I saved this as separate TGA image and used DEMDRAPE2 to create the .POV file. The image that resulted is shown at upper right. This is a view of central Italy looking north. Naples and Salerno are at the lower center of the map. The large mountain at the lower center is Mt. Vesuvius. Molise is on the north shore northeast of Naples.

I prepared a second view of the map using a POV-Ray feature called "water_level". This is a type of CSG command that "slices" the height field object and discards everything below the specified elevation. After slicing away everything at sea level and below, I saved the image (against a stark black background) as a TGA.

I first tried creating the ocean by adding a blue plane object to the POV-Ray file before saving. However, I was not satisfied because the resulting ocean looked flat and featureless. I instead sampled a blue bitmap I found on the Internet and opened it and the DEM in Paintshop Pro. By creating a mask of the DEM image and pasting it as a transparent selection onto the blue background, I was able to create the impression I wanted. I enhanced the effect by airbrushing "shoals" around the coastal and island areas of the map where they were missing. The result is shown in the second image at lower right.