Hello

I have a dem and a polygon featureclass for which i want to calculate the mean aspect for every single polygon.

I found a topic about this problem in the old esri forum , but unfortunaly i do not get a correct result.

1) Generate the ASPECT for the dem

2) Calculate COS and SIN for the Aspect-raster (COS = ([ASPECT] * 0.01745329)) (SIN([ASPECT] * 0.01745329))

3) Zonal Statistics to SUM the SIN and COS raster for every Polygon.

4) RASTER = 360 + ATAN2([SUM_COS], [SUM_SIN]) * 180 / pi

5) RESULT = MOD([RASTER], 360)

The result i get from the calculations seems to be correct for a few areas, but in others it is shifted of 90 or 180 degrees.

I don't know what i am doing wrong.

Thank you.

I have a dem and a polygon featureclass for which i want to calculate the mean aspect for every single polygon.

I found a topic about this problem in the old esri forum , but unfortunaly i do not get a correct result.

1) Generate the ASPECT for the dem

2) Calculate COS and SIN for the Aspect-raster (COS = ([ASPECT] * 0.01745329)) (SIN([ASPECT] * 0.01745329))

3) Zonal Statistics to SUM the SIN and COS raster for every Polygon.

4) RASTER = 360 + ATAN2([SUM_COS], [SUM_SIN]) * 180 / pi

5) RESULT = MOD([RASTER], 360)

The result i get from the calculations seems to be correct for a few areas, but in others it is shifted of 90 or 180 degrees.

I don't know what i am doing wrong.

Thank you.

[ATTACH=CONFIG]12944[/ATTACH]

To do this...

- Clip and mask your DEM to the polygon

- Convert the masked DEM to points, or...

- Create Random Points constrained by your landslide polygon which you can use to sample the elevation values.

Then