I have a question about the Topographic Openness module of Saga GIS 2.1.0 beta. In most literature I have read about Topographic Openness a radius in meters in used (for instance TO250 for a 250m radius). One of the articles in which this can be found is: http://www.geomorphometry.org/system/files/Anders2011geomorphometry.pdf
My question is: how is this radius approached in the module? Under options it says "Radial Limit", which has a default entry of 10000. Is this the same as radius, but then in a different measurement unit?
Thank you,
Robin Gabriner
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the "Radial Limit" is the search radius in map units. So in case you like to limit the calculation to 250m (and your map units are meters), simply use a radial limit of 250.
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Hi All, i'm trying to do topography opennes analysis for my DSM data in SAGA GIS. My question is how to run this analysis? What should be the set for the elevation, positif opennes, negative opennes? and how can i determine the radial limit value? I have the screenshot of my dsm data below
More information can be found in the SAGA User Guide and the tutorials.
You only require to set the "Elevation" dataset (which is your DSM), the other datasets are output datasets and will be created to show the results.
The "Radial Limit" determines how far the openness will be traced from each cell. The higher the limit, the more cells will get analyzed. This increases computation time, but also increases the accuracy of the result. As your dataset is rather small, you could set it to a value larger than the extent.
Best regards,
Volker
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi everyone,
I have a question about the Topographic Openness module of Saga GIS 2.1.0 beta. In most literature I have read about Topographic Openness a radius in meters in used (for instance TO250 for a 250m radius). One of the articles in which this can be found is: http://www.geomorphometry.org/system/files/Anders2011geomorphometry.pdf
My question is: how is this radius approached in the module? Under options it says "Radial Limit", which has a default entry of 10000. Is this the same as radius, but then in a different measurement unit?
Thank you,
Robin Gabriner
Hi Robin,
the "Radial Limit" is the search radius in map units. So in case you like to limit the calculation to 250m (and your map units are meters), simply use a radial limit of 250.
Hi All, i'm trying to do topography opennes analysis for my DSM data in SAGA GIS. My question is how to run this analysis? What should be the set for the elevation, positif opennes, negative opennes? and how can i determine the radial limit value? I have the screenshot of my dsm data below
Thank you,*
Herman
Hi Herman,
please have a look here to get a very basic overview on how to execute tools:
https://sourceforge.net/p/saga-gis/wiki/Executing%20Modules%20in%20SAGA%20GUI/
More information can be found in the SAGA User Guide and the tutorials.
You only require to set the "Elevation" dataset (which is your DSM), the other datasets are output datasets and will be created to show the results.
The "Radial Limit" determines how far the openness will be traced from each cell. The higher the limit, the more cells will get analyzed. This increases computation time, but also increases the accuracy of the result. As your dataset is rather small, you could set it to a value larger than the extent.
Best regards,
Volker