Terrain

SRTM Version 2 [GOV-FTP]
by NASA, NGA, DLR, ASI

Entry created by Andreas Jung.

Contains following datasets in DEM format: SRTM30 30" (~1km) worldwide/finished; SRTM3 3" (~90m) +-60°/semi-finished; SRTM1 1" (~30m) US-only/semi-finished. Semi-finished means: Water noise and anomalies removed (since V2), but voids due to RADAR-shadows still in the dataset. Version 2 also features extensive PDF documentation. Note: Link redirects to US government FTP server. [IMO] This dataset is more or less the only serious option for flight simulation (except the scenery is bound to a "special interest region" or small-scale). SRTM30 can be used without pain - it's quite small (less than 1GB), has no voids, and also contains the polar regions. In case you want to use SRTM3/SRTM1, you have to worry about voids and loads of data (~30GB uncompressed). Still, you get nothing less than the whole world in breathtaking resolution for free.

SRTM Version 2 [Seamless]
by NASA, NGA, DLR, ASI

Entry created by Andreas Jung.

Seamless data distribution using a web frontend.

SRTM3 Indices
by Andreas Jung

Entry created by Andreas Jung.

Be aware, that a 1201x1201 datagrid (typically found in SRTM3 files) is more than 16bit indices can handle. So one has to create smaller grids or switch to 32bit indices (which comes at the cost of a performance penalty of course).

Writing Endian Independent Code
by Promit Roy

Entry created by Andreas Jung.

It must be considered, that most terrain elevation datasets are stored in big-endian byte order. Most personal computers (even the MACs as of 2006) use little-endian byte order. So each pair of bytes needs to be swapped somewhere. This could be done in a preprocessor step, but the easiest way is to load up the DEM file as a byte-array, which is then written into a short-array, where each two bytes are concatenated together using bit-witchcraft. The linked gamedev article talks a little bit more in depth about it. It also features some C++ snippets.

Terrainmap
by John Childs

Entry created by Andreas Jung.

Good roundup of all kinds of terrain- and mapping-sources, as well as processing techniques. Home of Blackart, the famous DEM repair tool.

Virtual Terrain Project
by Ben Discoe

Entry created by Andreas Jung.

Huge collection of links and knowledge about terrain synthesis - presented in the context of the Virtual Terrain Project software. [IMO] If you are unable to find something terrain-related over there, you'll probably never find it.

Global Terrain Technology for Flight Simulation
by Adam Szofran

Entry created by Andreas Jung.

Explains the characteristics of a state-of-the-art terrain engine for flight simulation, based on the FSX.

Scene Completion Using Millions of Photographs
by J. Hays, A. Efros

Entry created by Andreas Jung.

The paper presents an image completion algorithm. It must be examined, wether this algorithm could also be used to repair unfinished SRTM3 files. [IMO] The sample images provided are impressive. Maybe this algorithm could also help to simplify the texturing process of 3D scenery objects using (incomplete) photographs.

Complex Terrain Curvature around Lisbon Airport
by Nicolas Kersting

Entry created by Andreas Jung.

Shows the complex terrain curvature onboard a LH A321 during the approach into Lisbon airport. [IMO] The reason why flight simulators should have bump mapping.

FS Global 2005
by Pilots

Entry created by Andreas Jung.

Commercial mesh scenery for FS2002/FS2004 based on SRTM3 data. [IMO] Besides the advertisement of the product, the website also discusses the SRTM3 dataset to some extent.

slashgeo
by slashgeo

Entry created by Andreas Jung.

News portal targeting the GIS community. [IMO] It's a good idea to subscribe to the newsfeed if you want to stay informed about GIS related topics.