Determining Slope from a GA feature to raster layer

[camdenlowrance]

I'm having issues determining the slope of my raster created from a GA layer.  I've searched around on the forums and made sure that my coordinate systems are all the same and are projected coordinate systems for my region.  My rasters seem to be accurate, but when I use the slope tool in spatial analyst I am getting results that are very steep, most of the slope raster has a nearly 90 degree angle.  I attached a screen capture of my results.  I have tried to calculate the slope from many different interpolation techniques (IDW, LPI, RBF, Kriging) and always seem to get this output.

[SteveLynch]

Camden

If you load the raster (that you want to create a slope of) into ArcMap, what coordinates do you see in the bottom right of the view? Are they in feet or meters?

What is the range of values in your raster, i.e. what are the min and max values? and what units are they in?

-Steve

[camdenlowrance]

Steve,

My coordinates I am inputting from a csv are in decimal degrees, but the elevation readings are in feet above sea level.  The units in the bottom right are decimal degrees.  I am working in the projected coordinated system NAD 1983 Georgia West, which uses US Feet as the linear unit.  The elevation raster I produced from an IDW GA layer has a range of ~ 56-64 feet, and the linear unit is feet and angular unit is degree.

[SteveLynch]

If you are in lat/Long then you are in an unprojected coordinate system. I.e you are in a geographic coordinate system.

You need to project you data!

Steve

[camdenlowrance]

Steve,

I'm still having issues projecting my data (i thought i had done so before posting this thread).  Do I need to first convert my latitude and longitude coordinates into feet and then load the .csv and continue on with my interpolation?  Or am I missing something with regards to projecting lat, long coordinates?

Thanks

[SteveLynch · Accepted solution]

Your input data, used to create the GA layer, must be in a projected coordinate system, i.e feet. The output grid, from GALayerToGrid, will then also be in feet.

Steve