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1. Readme for GCD 4.0 Beta

Geomorphic Change Detection 4.0 Beta Software

Produced by Joe Wheaton & Chris Garrard
Copyright © 2009-2010 Wheaton

Updated:  October, 2010

GNU Licnese

Developer can be contacted at or Joe Wheaton, Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Source code can be acquired from developer by request.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.  

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see (GLP v2 license).

If you do choose to modify the source code and redistribute it, please cite the Wheaton et al. (2010b) paper accordingly.

What does it do?

The GCD4 software was developed primarily for morphological sediment budgeting in rivers (i.e. geomorphic change detection). The volumetric change in storage is calculated from the difference in surface elevations from digital elevation models (DEMs) derived from repeat topographic surveys. As each DEM has an uncertain surface representation (which might vary in space and time), GCD4 provides a suite of tools for quantifying those uncertainties and propagating them through to the DEM of difference (DoD). The program also provides ways for segregating the best estimates of change spatially using different types of masks. The overall suite of tools is more generically applicable to many different spatial change detection problems.


Thank you for downloading our GCD 4.0 Beta Software. This version of the software is available in three formats :
  1. a Stand-alone windows application
  2. an ArcGIS 9.3.X plugin (toolbar)
  3. and an ArcGIS 10 plugin (toolbar)
Unlike the earlier Matlab versions (e.g. DoD Uncertainty Analysis Software v. 3.0), which were wizard based, this version uses a tabbed GUI dialog to set up a simulation within ArcGIS. Version 4.0Beta is a limited release, which does not yet include all the functionality of the Matlab Code (e.g. batch processing), but it does boast some new features and increased flexibility for the user. With this new interface, the notion of pathways through the code and referred to in the DoD3.0 documentation is no longer applicable. The former DoD3.0 version limited the user to five types of uncertainty analysis. This version allows many more possible types of uncertainty analyses and future releases will extend on that.


User Requirements:

  • Some understanding of DEM differencing and geomorphic change detection
  • Familiarity with ArcGIS

System Requirements:

  • ArcGIS 9.3.X (not tested on 9.1 or 9.2) or ArcGIS 10.X for Plugins
  • ArcGIS Spatial Analyst and 3D Analyst Extensions will be necessary to derive inputs and build DEMs
  • Windows OS with latest version of .NET (use Windows Update)
  • Machine with enough RAM to handle your input rasters (4 GB or more recommended)

Input Data Requirements:

Everything you need to run this software can be derived from a raw x-y-z point cloud of your topographic survey data. From this you can build a TIN or terrain surface and derive a raster DEM. You can also derive a point density grid and slope analysis (the only two required inputs for the default fuzzy inference system). The basic requirements are:

  • Input data are on collinear rasters of equal extent and resolution (how do I do that?)
  • Input elevation data are assumed to be:
    • In meters and on the same vertical datum between surveys
    • Pre-processed to remove systematic errors and obvious busts (see pages 9-15 of this tutorial for help)
  • Inputs to Fuzzy Inference system:
    • If you use slope input rasters, slope should be calculated as a percent slope
    • If you use point density rasters, point density should be calculated in points per square meter (I tend to use a 5 m square moving window to do this calculation)
    • If you use roughness input rasters, roughness heights should be reported in meters
    • If you use 3D GPS Point quality input rasters, quality should be reported in meters
    • If you use water depth input rasters, depth should be reported in meters
  • Inputs to Geomorphic Interpretation / Masking
    • Whether you use the classification of difference method or straight masking method, the input masks should be raster integer grids with 1, 2, 3, … n corresponding to unique mask categories (you will be prompted to enter what linguistic categories these values correspond to)

Installation Procedure 

Read below or see installation video tutorial.

For ArcGIS 9 and/or 10 Plugin:

To install, make sure that ArcGIS  is not running and any previous versions of GCD are uninstalled. Locate the downloaded installation file and run it.

You can choose the installation directory (or just keep the default)


Confirm installation by clicking next on the next screen. After you’ve completed the installation hit finish.

To use the software, you will need to start ArcGIS ArcMap. Right click on the toolbar and make sure the ‘Geomorphic Change Detection’ toolbar is checked on. Once you’ve turned it on, the toolbar will appear:


You can dock the toolbar if you wish by dragging it onto the toolbar space.



If you ever need to uninstall the software, simply open your Control Panel, and go to uninstall or change program and remove it. It is important that if you wish to uninstall ArcGIS, that you first uninstall the GCD plugin. It will not be able to uninstall if ArcGIS has already been uninstalled. See also Video Tutorial on Uninstall.

Stand Alone Install

The stand alone installation is even simpler as it has no ArcGIS dependencies. Just run the *.msi file and follow the wizard prompts. Then run the program form your Programs menu.

Source Code & Other Versions:

This release was made as an alternative to the Matlab Code in earlier versions, which required users to have a Matlab License, the Matlab Fuzzy Logic Toolbox installed, and a limited knowledge of Matlab. That version was made available to accompany a paper published in Earth Surface Processes and Landforms (Wheaton et al., 2010b),  the Wheaton (2008) thesis, and the Wheaton et al. (2010a) RRA paper.  That code was provided as supplemental information with the ESPL paper so that readers could test or extend the code as they see fit for their purpose. The code for this version is available upon request for educational, research and non commercial purposes. However, as it is a C++ library and C# for the GUI, it is not anticipated that many/any users will be wanting to get under the bonnet.

Future Releases, Support & Updates

The DoD software is under ongoing development. That development is extending the software to other survey technologies, capability of handling larger raster sizes, and other change detection problems. At the time of this release, the code is being refactored into an open-source C++ library, which will be the backbone to a web-application and an ArcGIS plug-in. However, this Matlab version of the software is perfectly functional and should be easily extendible to users familiar with Matlab. Given the ease of development within Matlab, we felt it was important to make this version of the code available to others. Future releases will just be of the C++ library, and will automatically apply to the web-application that anyone will be able to use without proprietary Matlab or ArcGIS software licenses.


No formal support is available with this free software. I encourage you to see if a solution exists in these help pages first, and use the GCD Discussion Board to post questions.

Good luck.


The original Matlab versions were coded by Joe Wheaton and James Brasington. with financial support from the University of Southampton School of Geography, Aberystwyth University Institute for Geography and Earth Sciences. This release was coded by Chris Garrard at Utah State University's RSGIS Lab under the direction of Joe Wheaton and with generous financial support from ICRRR.


  • Wheaton JM. 2008. Uncertainty in Morphological Sediment Budgeting of Rivers. Unpublished PhD, University of Southampton, Southampton, 412 pp. Available at:
  • Wheaton JM, Brasington J, Darby SE, Merz JE, Pasternack GB, Sear DA and Vericat D. 2010a. Linking Geomorphic Changes to Salmonid Habitat at a Scale Relevant to Fish. River Research and Applications. 26: 469-486. DOI: 10.1002/rra.1305.
  • Wheaton JM, Brasington J, Darby SE and Sear D. 2010b. Accounting for uncertainty in DEMs from repeat topographic surveys: Improved sediment budgets Earth Surface Processes and Landforms. 35(2): 136-156. DOI: 10.1002/esp.1886.