Deriving slope angle value from DEM using ERDAS Imagine

Question

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.

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.

Answer 1

Have you though of just using the free GDAL tool?

http://www.gdal.org/gdaldem.html

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.

Answer 2

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.