Terrain Ruggedness Index (TRI) and Vector Ruggedness Measurement (VRM) - Two new Arc Hydro functions that quantify ruggedness on a DEM

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09-04-2020 09:21 AM
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EzraBosworth-Ahmet
Esri Contributor
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The Importance of Terrain Analyses

Quantifying the characteristics of terrain can be beneficial in many analysis workflows including sediment transport modelling, ecological studies, geomorphological evaluation of land forms, and landslide hazards assessment. To help with terrain analysis, Arc Hydro is adding a Terrain Ruggedness Index (TRI) tool and a Vector Ruggedness Measure (VRM) tool to its terrain pre-processing capabilities.

 

How TRI and VRM contribute to Terrain Analyses

Terrain Ruggedness Index:

   TRI expresses the amount of elevation difference between adjacent cells of a DEM. Using methodology developed by Riley et al (1999) and published in the paper “A Terrain ruggedness Index That Quantifies Topographic heterogeneity”, the tool measures the difference in elevation values from a center cell and eight cells directly surrounding it. Then, the eight elevation differences are squared and averaged. The square root of this average results is a TRI measurement for the center cell. This calculation is then conducted on every cell of the DEM.

 

 Vector Ruggedness Measure:

   VRM provides a way to measure terrain ruggedness as the variation in three-dimensional orientation of grid cells within a neighborhood. Slope and aspect are captured into a single measure and used to decouple terrain ruggedness from just slope or elevation. The VRM was first proposed by Hobson (1972) in “Surface roughness in topography: quantitative approach” and was later adapted by Sappington et al (2007) in “Quantifying landscape ruggedness for animal habitat analysis: A case study using bighorn sheep in the Mojave Desert.”

 

   Both tool scripts use geoprocessing workflows developed by Dr. Barry Nickel, a professor at University of California Santa Cruz.

 

Where to Find TRI and VRM

Many ecologists and geologists have employed TRI and VRM to further their research and understanding of terrain. Prior to this tool release, analysts had to derive both TRI and VRM through a series of geoprocessing steps or had to write their own custom tool. Now, both tools are available under Arc Hydro's Terrain Preprocessing toolbox in ArcMap 10.8.0.37 and ArcGIS Pro in Arc Hydro build 2.6.26. Future releases of Arc Hydro will also support the tools.

 

 

How to Use the Tools

  The TRI tool requires only a DEM as an input. The output is a TRI raster data set that expresses the amount of elevation difference between adjacent cells of the DEM in meters. Output values are dependent on input DEM resolution.

 

 

   The VRM tool has two input parameters. One is the DEM for analyses, and the other is an integer specifying neighborhood size for analyses. A larger window size can be useful, but often causes a smoothing effect on the landscape, so as a default, the window size is set to 3. The output is a VRM raster data set that is a dimensionless ruggedness value between 0 (flat) and 1 (most rugged). Typical values for natural terrains range between 0 and 0.5, with rugged landscape defined to be greater than 0.02.

 

20 Comments
AlbertHeim
New Contributor

This is good news, and exactly what I need! 

ErinMorrison
New Contributor

Hi! I'm so glad that someone has created a TRI function. However, I tried to run it and am coming up against this error:

Failed to execute. Parameters are not valid.
ERROR 010391: Kernel file is not provided or does not exist.
Failed to execute (FocalStatistics).

Any help would be appreciated, thanks!

Wei-HsinFu1
New Contributor II

ErinMorrison,

I had the same problem, ERROR 010391 when running in Pro. The problem went away after I reinstalled ArcHydro with a different installation file which can be found here:

http://downloads.esri.com/archydro/archydro/setup/Pro/

 

The first installation file I used does not have a label for version and I believe some Esri page says it works for all Pro version. But apparently it does not. You can find installation files for Pro 2.0 and 2.6. I use Pro 2.6 and the second installation works fine.

I did not try it with ArcMap. Here is the page with installation file for ArcMap 10.8.

https://downloads.esri.com/archydro/archydro/Setup/10.8/

 

Here is the page that helped me:

https://community.esri.com/t5/water-resources-documents/downloading-and-installing-arc-hydro-tools/t...

 

Hope it works out for you.

 

EzraBosworth-Ahmet
Esri Contributor

It has come to my attention that my initial post linked to a version of Arc Hydro that had an error in the TRI script. I have since updated the blog to link to the right download locations.

@ErinMorrison, I hope you were able to get the tool working.

 Thank you @Wei-HsinFu1 for bringing the issue to my attention and clearly explaining the solution!

SimaMohtashami1
New Contributor

Hi

I am trying to run "Terrian Ruggedness" over a DTM (2m) for my study area. unfortunately the tool does not produce any result, ending up in following error, any idea how I can solve it?

Thanks, Sima

010240: Could not save raster dataset to <value> with output format <value>

EzraBosworth-Ahmet
Esri Contributor

@SimaMohtashami1, what is your output file format? Is your output ending with a ".tif"?

SimaMohtashami1
New Contributor

I didn't define any prefix for the output raster, so I guess it should be created in Grid format, when the tool is successfully run.

Now I tested to save the output raster in a file geodatabase, and it went well! I don't know what the explanation can be!

It would be nice to provide more specific description on input/output file in a help-window of the script, to achieve more problem-fri runs of the tool.

Thank you, Sima

 

CatherineMcElroy
New Contributor

I've downloaded ArcMap 10.8.0.33 and the 10.8.0.34x64 version and the Terrain Ruggedness Index isn't listed, nor the Vector Ruggedness Measurement for either version. All of the other tools seem to be there, however. I'm not sure if it's a version problem. Has anyone found this as well? Thank you!

DeanDjokic
Esri Contributor

Please make sure you look into "Arc Hydro Tools Python" toolbox under the "Terrain Preprocessing" toolset.  They should be there at the bottom of the list.

DeanDjokic_0-1626074076732.png

 

Brume
by
New Contributor

Failed to execute. Parameters are not valid.
ERROR 010333: Invalid Weight neighborhood mask:
Failed to execute (FocalStatistics).
('line 219', 'c:\\program files (x86)\\arcgis\\desktop10.8\\ArcToolbox\\Scripts\\archydro\\terrainruggednessindex.py', '')

 

Does any know how to solve the above problem encountered when calculating Terrain Ruggedness Index (TRI)?

Thanks!

EzraBosworth-Ahmet
Esri Contributor

@Brume, After further inspection of the ArcMap build, it looks like the auxiliary files needed for the tool to run successfully were not included in the download. I have created a new Arc Hydro build that has the required files. Please uninstall the existing build on your machine and install the new build here. The TRI tool should work as expected. I have also updated the blog post to now link to the correct version of the build.

Thanks,

Ezra

CinziaForcina
New Contributor

Hi, 

I am trying to run "Terrian Ruggedness" over a DTM 5x5. But the process doesn't create anything and reports the following error:

('line 211', 'c:\\program files\\arcgis\\pro\\Resources\\ArcToolbox\\Scripts\\archydro\\terrainruggednessindex.py', 'AssertionError')

Can you help me?

 I use Arcgis PRO, I tryed to execute the tool from two last version there are on download page.

Thanks

IsaacPope
New Contributor

@EzraBosworth-Ahmet I am having the same issue as @CinziaForcina:

 

('line 211', 'c:\\program files\\arcgis\\pro\\Resources\\ArcToolbox\\Scripts\\archydro\\terrainruggednessindex.py', 'AssertionError')

Is there any way of fixing this?

martinschaefer1
New Contributor III

I am likewise experiencing the AssertionError, has anyone found a solution?

EzraBosworth-Ahmet
Esri Contributor

Hi @martinschaefer1 , I am having trouble reproducing this error on my end. Can you provide some more information on the software setup and workflow? This document outlines the best way to report the issue for us to troubleshoot effectively.

martinschaefer1
New Contributor III

Hi @EzraBosworth-Ahmet  I've since been able to run the same workflow with the same data on a different PC that is not set up by our central IT, and it works. So if you cannot reproduce it and I can run it on a different setup I have to assume they've done something strange. PCA won't run either on that PC.

Thanks you for checking back.

EzraBosworth-Ahmet
Esri Contributor

@martinschaefer1 okay, thanks for the update!

TianyiShen
New Contributor

Copying kernel files to temp directory: D:\ArcGis\Pro\Yarlung Tsangpo\scratch\TerrainRuggednessKernels
Calculating northwest raster ...
('line 211', 'c:\\program files\\arcgis\\pro\\Resources\\ArcToolbox\\Scripts\\archydro\\terrainruggednessindex.py', 'AssertionError')
('line 211', 'c:\\program files\\arcgis\\pro\\Resources\\ArcToolbox\\Scripts\\archydro\\terrainruggednessindex.py', 'AssertionError')

what is the probelm about line 211?

AyushiSharma
New Contributor

Hello! I have ArcMap 10.6, can i install the latest arc hydro toolbox on my system as I need to use the VRM tool. Thanks

EzraBosworth-Ahmet
Esri Contributor

Hi @AyushiSharma - you will need ArcMap 10.8 with at least the 10.8.0.37 Arc Hydro build to get access to VRM and TRI.