Virtual Terrain Generation with Metadesic™ Compiler

The latest addition to MetaVR’s Windows-based PC visualization product line is the Metadesic terrain compiler, which supports the Metadesic architecture by compiling imagery and elevation source data into the three-dimensional and self-contained MDS format. The resulting virtual terrain is suitable for real-time rendering in perspective view applications such as image generators and modeling tools. The Metadesic Compiler can interact with, or even be embedded into, the visualization application.

The Metadesic Compiler:

• Has a simple, data-driven interface
• Can be embedded within larger applications
• Accepts GIS imagery sources: Geotiff, CIB, MrSid™
• Accepts elevation sources: DTED, SRTM, USGS, XYZ
• Accepts vector data: ArcInfo Shape point features, linears/aerials

The Metadesic Compiler also supports the Navy's Portable Source Initiative (PSI) standard for terrain database source data.

	Real-time VRSG screen capture of a KC-45 aircraft refueling an F-15 over the Ontario, California, area of MetaVR's North America terrain. Click Zoom to see a high-resolution version.

The Metadesic architecture has many benefits over conventional visualization architectures, such as use of geocentric rather than projected coordinate systems, ability to handle live update of terrain, scalable and robust terrain generation, and index-free demand paging.

About Metadesic tiles

An important concept in the Metadesic architecture is the geodesic tile. The tile defines the geographic extent of a logical unit of work in the visualization pipeline that flows from sensor acquisition, to registration/enhancement of source data, through compilation of three-dimensional terrain, right to rendering of a perspective view. Metadesic tiles are autonomous in that they can be compiled, viewed, and updated independently. Likewise, for coordinated applications, the hundreds of tiles that are needed to populate the entire scene are seamlessly rendered by the image generator. Each tile remains individually addressable and can be updated on a frame-by-frame basis.

	Source elevation and GeoTIFF imagery data.

	The resulting Metadesic virtual terrain tile.

About the compilation process

The Metadesic Compiler is network capable and communicates via UDP messages to any listening application when compilation of an individual tile is completed. In this way, the visualization maintains a living terrain that can change on-the-fly at any given frame.

You specify the source data, extents, and the directory in which to output the generated terrain tiles in one of two ways:

• Supplying values in the Metadesic Compiler wizard
• Running the MdsCompiler command-line executable

Running the Metadesic Compiler wizard is an easy way to specify the source data, extents and target location for the resulting terrain tiles in standard Windows wizard interface. You can save the settings to edit in Notepad or include in an application as a batch job, or start the compilation immediately.

Running the command-line executable as a batch job enables multiple CPUs on different (and disparately located) networked machines to process a large quantity of source data at once. This includes cueing them to generate tiles when imagery becomes available. You can also use the command-line compiler to specifically regenerate just one tile or a subset of tiles; the geometry and texture information encoded in the tile is reused except where new source information is provided. MdsCompiler accepts basic command-line input that describes where to place tiles, where to retrieve source data, and geographic areas of interest.

About the color fusion imagery shown

The Metadesic Compiler makes use of a color fusion technique, which blends the higher resolution greyscale imagery with lower resolution color imagery. For some areas of MetaVR's North America terrain, the available source imagery was .5 to 1 meter grayscale MrSid imagery, which was overlaid with 1 to 5 meter natural color imagery. For example, the Ft. Wainwright area has .5 meter grayscale MrSid imagery fused with 1 meter color Geotiffs. Due to the way the human eye detects details in value changes (contrast) the resulting compiled terrain appears as very detailed color imagery.

Each new Metadesic Compiler software license is delivered with a 1 TB external LaCie hard drive that contains MetaVR’s North America 3D terrain in Metadesic terrain tile format compiled from 5 and 15 meter resolution natural color imagery. Also included with the complied terrain is the 15 meter source imagery and elevation data.

You can order the Metadesic Compiler directly from MetaVR.