The DEMmaker suite of software applications produces data products containing surface shape, reflectivity, and geomorphology (craters and rocks) for a desired planetary surface based on statistically accurate size and frequency distributions of geologic and surface impact features. The current version can produce models at virtually any resolution or size for any location on the Moon. Remote sensing data can be incorporated to underlie the synthetic landscape with real data where available. The software suite is driven by a graphical user interface (GUI) that lets the user specify which tools of the suite to run, allowing flexibility in the products output by the package.

The software comprises several modules. The Crater Generator is the primary tool in the suite and has the greatest impact on generating terrains. It generates, based on a power law, a random distribution of craters in the region of interest. The Rock Generator distributes rocks on the landscape, also based on a power law, with rock shapes selected randomly from a library of rock models. The generator selects a random number of rocks, depending on what is expected in the given surface area.

The DEMmaker uses the crater and rock distributions and generates digital elevation maps (DEMs). The DEMmaker tool can also incorporate coarse or fine terrain data from exploratory missions. The resulting output is a high-resolution DEM that is a smooth blend of mission data and synthetic features based on scientific statistical distributions. The current software outputs DEMs using a polar stereographic projection following the Planetary Data System (PDS) format including an image (.img) file with the elevation data and a corresponding label (.lbl) file with supporting information.

The Tile Warper tool models systematic errors into the “truth” synthetic DEMs. This allows the user to construct a new DEM with different sample distances than the original with additional altitude errors superimposed. Both the magnitude and the spatial correlation of the added errors can be tuned to best model the expected errors for the created DEM.

The DEMs produced by DEMmaker enable researchers to study a wide variety of problem domains. The DEMs are seamless and can be produced at multiple, user-defined resolutions for a given area. The availability of a single, customizable application for the generation of synthetically enhanced terrain would eliminate the cost of duplicate software development across the aerospace industry, consolidate the resources associated with sustaining engineering and certification of this application, and promote a common environment for mission analysis and system performance comparisons.

This work was done by Thomas Criss, Norberto Lopez, Timothy McGee, James McGovern, John Reid, and Uday Shankar of The Johns Hopkins Applied Physics Laboratory LLC for Johnson Space Center. MSC-24722-1

NASA Tech Briefs Magazine

This article first appeared in the November, 2015 issue of NASA Tech Briefs Magazine.

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