Hi once more! Ralf Gerlich wrote: > I can assure you that I will provide support to you with everything I > learned about scenery design, file formats and coordinate systems in the > FlightGear world. I will not be able to assist you much in coding, and > specifically not in the area of 3D programming, but I will try to do my > very best to help you being successful in the areas I can help with.
So why not start right now? (forgive me if you already know a lot of the following). So what we have in the database is a logical setup of the terrain data in terms of polygons describing aerial features (forest, town, cities, etc.) in terms of polylines describing linear features (roads, railroads, small streams, etc.) "Logical setup" means that the data is not yet directly associated with a texture or in case of linear features also with a width, but this is typically done when extracting the data from the database and converting it to a TerraGear-friendly format in the TerraGear working directory. So the actual association of type of landcover and a texture is established by the script that does the conversion. Instead of converting the data to a TerraGear working directory it would be possible to convert it to a file format useable by your scenery engine, in which the polygons and lines would be associated with a "display type" defining texture and markings, and in case of the lines also with a width. The positions in the database are in WGS84 format, i.e. in geodesic coordinates according to the WGS84 ellipsoid approximation of the earth's surface. You can use the functions in simgear/math/SGGeodesy.hxx to convert these to cartesian coordinates. These functions are, however, a bit computationally expensive - at least when used hundreds or thousands of times per frame - so a pre-calculation of the actual cartesian coordinates used for display would be a good idea. The cartesian coordinates are used to actually model the earth as a round shape instead of a flat shape in display space, which makes things a lot easier (latitude-longitude wrap-around) and also more realistic (ever seen the curvature of the earth from high above?) The other data you will probably need is the elevation data. Most of the elevation data we have is from SRTM, the Shuttle Radar Topography Mission. The data consists of raster files in different formats, a "non-standard" format named HGT and as GeoTIFF. We can of course make this available in a suitable raw binary format. As I have some experience in working with all that data and the formats, I could write the conversion tools. We'd just have to agree on a format for the files. Cheers, Ralf ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
