topic Flow Direction Cell Count in ArcGIS Spatial Analyst Questions

Flow Direction Cell Count

TomGebhard — Wed, 27 Mar 2013 01:59:19 GMT

First post! I am new to GIS, so bear with me.

I created a flow direction layer, and the layer has more cells than the input surface layer. How can this be? The reason this is a problem for me is that I am using the direction layer to calculate flow accumulation, and I would like to translate this to drainage area.

Thanks in advance

Re: Flow Direction Cell Count

curtvprice — Wed, 27 Mar 2013 02:13:57 GMT

First post! I am new to GIS, so bear with me.

I created a flow direction layer, and the layer has more cells than the input surface layer. How can this be? The reason this is a problem for me is that I am using the direction layer to calculate flow accumulation, and I would like to translate this to drainage area.

Thanks in advance

Before you calculate flow direction make sure that the environment is set up not to resample anything:

These should be default or same as your surface raster
- outputCoordinateSystem
- cellSize

Also, it's best practice to set the snapRaster to the surface raster.

Re: Flow Direction Cell Count

TomGebhard — Wed, 27 Mar 2013 19:33:30 GMT

Before you calculate flow direction make sure that the environment is set up not to resample anything:

These should be default or same as your surface raster
- outputCoordinateSystem
- cellSize

Also, it's best practice to set the snapRaster to the surface raster.

That worked. Thanks!