Directories to store commonly used external datasets.
A key feature of this repository is downloading and organizing digital elevation models (DEMs) to calculate the terrain elevation in mean sea level (MSL) and when using other repositories to generate aircraft track altitudes. For defaults, the scripts will download GLOBE. For scalability, default directories for many DEMS are provided in this repository, however only the default DEMs will be populated during initial setup.
These defaults are based on the availability of Matlab Mapping Toolbox functions to read and identify files. We recognize that GLOBE does not have the same resolution as USGS 3D Elevation Program (3DEP) Datasets from The National Map / National Elevation Dataset (NED) OR SRTM1 / SRTM3. These differences are summarized by extending a table found in the SRTM documentation:
| Posting (sample spacing) | SRTM name | DTED equivalent | Other |
|---|---|---|---|
| 1 arc-second | SRTM1 | DTED2 | |
| 3 arc-second | SRTM3 | DTED1 | |
| 30 arc-second | SRTM30 | DTED0 | GLOBE, GMTED2010, GTOPO30 |
1 and 3 arc-second data are often formatted as hgt (SRTM), ArcGrid, GridFloat, or IMG files. You can review by inspecting formats listed by the USGS Elevation Products (3DEP) or the SRTM data availability. The Matlab Mapping Toolbox currently does not fully support these formats. Specifically, while arcgridread can read a ArcGrid or GridFloat file, it can't read multiple files from a directory or filter based on latitude and longitude limits, such as globedem.
SRTM1 and SRTM3 data are available in the DTED format via mail order. According to the NGA, distribution of DTED2 and DTED1 are authorized to the Department of Defense, U.S. DOD contractors, and to U.S. Government agencies that support DOD functions. Through these means, MIT Lincoln Laboratory has 1 and 3 arc-second data in the DTED format, however they are not authorized to release this datasets to the public.
Data download directory from the FAA. This includes data from the 28 day FAA NASR and Digital Obstacle File (DOF) and aircraft registry.
Administrative and oceanic vector data provided by Natural Earth Data.
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