The TerraFlow-Extension for ArcGIS® 8.x

Disclaimer:

The software provided on this page is not in a final release state. Therefore, no warranty whatsoever can be given, and using this software is done on the sole risk and responsibility of the respective user.

This website is of a temporary nature and might move soon. Our apologies...

Participating Research Groups:

Summary:

For a project summary, please see the TerraFlow-Project pages at Duke University. The URL for the main page is:  http://www.cs.duke.edu/geo*/terraflow. This project bundles the TPIE-library (also available from Duke University), see  http://www.cs.duke.edu/TPIE.

Download Instructions:

For installing the TerraFlow-Extension on a Windows®-based platform, please follow these instructions.

• Download the zipped DLL-file from here (Version: 20040525).
• Put the zipped DLL-file anywhere on your local disk drive.
• Unzip the zipped DLL-file.
• In the directory containing the DLL-file, execute (with Administrator permissions) the command: regsvr32 TerraFlowExtension.dll.
• In ArcMap®, activate the extension via Tools->Customize->Toolbars (check the "TerraFlowExtension"-box).

The extension should process any raster set that ArcGIS® 8.x is able to read (any supported data type for elevations is supported by the extension). It automatically builds multiresolution pyramids for fast rendering of the terrain.

Notes:

Properties: The temporary directory for TPIE-scratch files is initialized from the TEMP environment variable.

Flow Direction: The call to this method generates two raster datasets for any given input raster IGRID and output raster OGRID:
  D_IGRID: Flooded terrain raster representation.
  OGRID: Raster representation of flow directions
Beware of the "13 characters"-limitation on the length of ArcGIS®-filenames! The filenames will be truncated to at most 13 characters.

Flow Accumulation: The call to this method for any given input raster IGRID first invokes the "Flow Direction"-method with input raster IGRID and output raster D_IGRID, hence generating F_IGRID (flooded terrain) and D_IGRID (directions) as a byproduct.

Compute Streams: This method simply replaces all values below the given threshold by NoData. It can also be used to convert the flow accumulation output from float to int.

Known Limitations:

At present we are aware of the following limitations:

• The "Flow Accumulation" method properly recognizes if the grid to be processed has already undergone a "Flow Direction" process. It does not exploit this fact and instead returns from the method invocation.
  
  Status: We are working on this problem.
  
  Workaround: Delete the raster datasets (see above) produced during the previous run.
  
  
• The "Save Flat Areas" and "Save Sink Watersheds" checkboxes in the "Flow Direction" dialog box are disabled.
  
  Status: This issue has a very low priority. If you want this feature to be included, please raise its priority by sending email to jan at math uni-muenster de
  
  
• The extension does not seem to work with ArcGIS® 9.0 due to a change in the way DLLs are registered.
  
  Status: We do not have access to ArcGIS® 9.0 (yet!), so we cannot confirm this problem.

If you experience problems, please send email to one of the people listed above. However, we cannot provide general ArcGIS®/Windows® support.

Ongoing Work:

The work described on this page is part of an ongoing joint research effort between the participating groups.

For comments, questions, or suggestions, please contact one of the authors (adresses at the top of this page). Thank you!

Acknowledgements:

We gratefully acknowledge support from the following agencies:

• National Science Foundation (USA): ESS grant EIA-9870734, RI grant EIA-9972879, CAREER grant CCR-9984099, and U.S.-Germany Cooperative Research Program grant INT-0129182.
• German Academic Exchange Service (Germany): Grant No. D/0104616.