I am trying to calculate the steepness of each pixels (30m) from the DEM of 2m resolution. I have made use of ERDAS Imagine - Slope function and returns a contour-like pixel image. The pixel value between contour is null in value. I have also tried to resample the slope image to 30m pixel but i don't know why many pixels return null value even it is overlapped with lots of contour-like pixels.

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Is there any method to calculate the steepness of each pixels in the DEM?

What i want to do is to make use of DEM to filter the flat area in the image classification.


Have you though of just using the free GDAL tool?


It can run in windows using OSGEO4W and can ouput .img files.

For Imagine 8 it goes something like...

From Spatial Modeler: This model is found in the file <.IMAGINE_HOME.>/etc/models/Slope_percent.gmd.

From Image Interpreter: Select Topographic Analysis... | Slope.... Under Output units select degrees / percent or similar. To view or edit the model, click the View... button in the Surface Slope dialog.

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IMAGINE's standard Slope operator or functionality uses a raster image with elevation as the pixel value. (Is your input like that, or what explains the Contour line -like image?)

http://community.hexagongeospatial.com/t5/Spatial-Recipes/Quadratic-Method-for-Slope/ta-p/1913 includes an alternative Slope method.

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