Announcing TerraSTREAM 0.4
We are happy to announce the release of the fourth beta of TerraSTREAM. TerraSTREAM perform flow modeling and terrain analysis tasks on very large digital elevation models and works equally well on TIN and grid DEMs. The algorithms used in the libraries have provable efficient performance in the worst case, even on very large terrains that do not fit in the main memory of the computer. TerraSTREAM 0.4 comes with direct MapInfo and ArcGIS support as well as a simple standalone graphical user interface and powerful command line tools that can be used alone or integrated into most GIS environments using scripting. For more information about this release and for contact information, visit http://madalgo.au.dk/Trac-TerraSTREAM/.
This TerraSTREAM release contains the following major features:
- Hydrologically Condition DEMs
- Prepare a DEM for flow analysis by removing "insignificant" sink(pits) by flooding them. A sink is insignificant if its height is smaller than some user specified threshold.
- Compute Flow Routings
- Compute flow directions for each data point in a DEM. This can be done using either SFD or MFD routing and with sophisticated flat routing techniques.
- Compute Flow Accumulations
- Accumulate amounts of, e.g., water on a DEM along flow paths.
- Construct a Watershed Hierarchy
- Construct a Pfafstetter labelling of the watersheds of a DEM.
We would like to thank all of our testers, we have received a great amount of valuable feedback. If you are interested in TerraSTREAM development and discussions we encurage you to subscribe to our (low volume) mailing list here: http://mailman.nfit.au.dk/mailman/listinfo/madalgo.au.dk-terrastream-devel. Future releases will be announced to that mailing list.
TerraSTREAM can be downloaded from http://madalgo.au.dk/Trac-TerraSTREAM/wiki/Download. We have prepared builds for Windows, Mac OS X, and some flavors of linux.
Changes between 0.3 and 0.4
TerraSTREAM has seen many changes since the 0.3 release. Many of these changes are under the hood, but a few are very visible to most users as well. Most notably, the command line executables have all been renamed and they now all have "ts-" prefixed to their original name. This makes it much easier to see what modules are actually part of TerraSTREAM once it's been installed - but be careful to change any scripts you might have that use the command line tools. The output format of files have also changed and TerraSTREAM now tries to construct a file in a format that matches the file extension given by the user(ticket:39, ticket:44, ticket:64). Finally, one can now specify where TerraSTREAM stores temporary files directly on the command line, using the new --tmp-path option, the graphical frontends has been updated to incorporate this feature.
Here is a list of some of the issues that have been addressed in this release of TerraSTREAM.
- Negative inputs for the conditioning threshold parameters should be caught.
- ArcGIS console loginfo output should not print empty lines
- Progress indicators should probably print only one text line - also in extensions_ e.g. in the ArcGIS extension
- ArcGIS grid writer output format
- ArcGIS scripts printing is delayed
- GDAL grid writer output format
- ArcGIS Driver Should Support ESRI Grids
- Limitation of TPIE file path length to 128 characters
- Projection information is deleted when using TerraSTREAM
- aspects/gradients computation should use grid metadata
- Command line tool crashes when overwriting on windows
- Output files between modules should respect the tmp dir setting
- Localization: Decimal separators
- Output files and extensions
- General flooding needs user interfaces
- Crash when opening invalid streams
- Gracefully handle user exceptions
Changes before 0.3
See the release announcement for 0.3.
Known Bugs and Issues
- The frontends provided for TerraSTREAM 0.4 do not work on TINs. Even though the core components are available for TINs we have not yet developed user-friendly front ends for these since we have not determined what kind of TIN file formats should be supported. If you would like to use TerraSTREAM on your TINs please give use information on the type of file format you use by replying to ticket:8.
- The memory usage on Windows has been limited to 500 megabytes due to issues with allocating large chunks of consecutive memory cells. We are working on fixing this, this is documented in ticket:43. (Note that since TerraSTREAM is very good at utilizing the disk you can handle very large terrains with 500 megabytes of memory just fine)
TerraSTREAM 0.4 is available from http://madalgo.au.dk/Trac-TerraSTREAM/.
Note that TerraSTREAM is beta grade software. Bug reports and feature requests are very welcome and will hopefully result in more stable and capable future versions of the software. Please attach the output from the command to the bug report, if possible.
Cheers, The TerraSTREAM Developers - August, 2008.