Tileset/Geoset Specification

Geographical datasets in TerraVision are managed with a higher order construct, referred to as a GeoPyramid. Although this interface hides much of the details of (remotely) accessing tilesets, some familiarity with the tsmAPI library is required; see:

http://www.ai.sri.com/tsmApi/api-new.html

GeoPyramids are created with calls to TsGeoCreate(). The client code specifies the URLs of the image and DEM tilesets, along with a packet of various connection-oriented parameters (constructed through the tsmAPI interface).

A rendering thread maintains a list of GeoPyramids from which to draw a scene. GeoPyramids are added to the list via calls to tvAddDataset(), and likewise removed from the list with tvRemoveDataset(). A convenience function exists that will apply a user-provided function to all GeoPyramids associated with a rendering thread: tvForallDatasets().

Three coordinate systems are directly supported to provide convenient spaces for operations on geographical data. The Geodetic Coordinate system (GDC) identifies points with the tuple (longitude, latitude, elevation). Points in the Geocentric Coordinate system (GCC) are identified with (x,y,z) offsets from the planet's center. The Local Vertical Coordinate system (LVCS) is a local Cartesian coordinate system (x,y,z), with the Z axis in the up direction. Conversion routines exist to transform from one space to another: TsGCCtoGDC(), TsGeoLVCStoGCC(), TsGeoGCCtoLVCS().

API