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Creating Swiss Hillshade

September 02 2011 | 0 comments
Categories: ArcGIS Methods, Map Data, Symbology

Hi,

I am trying to create the beautiful hillshade like that shown of Crater Lake for a small scale map of Myanmar showing the surrounding countries.

I have a DEM 90 meters resolution with its native coordinate system in WGS 1984. I projected the raster to the coordinate system that my company uses for map making: Indian_1954_UTM_Zone_47N.

Then I downloaded the hillshade tool, and added to my toolbox.

I wasn't clear exactly on whether I should set the z factor since I had already projected the raster. But I set it at .00000900 because Myanmar falls about 20 N to 5 N.

I then let ArcMap do its stuff and I got three output rasters: the DEM, Filtered, and the Aerial.

I ordered and adjusted those rasters according to the documented help in the
hillshade help. (See attached screenshot).

However, my output doesn't look beautiful or even remotely resemble what I would like.

Do you have any advice as to where I've gone wrong in the process?

Many thanks.

Mapping Center Answer:

If you already projected your raster so that it now has the x and y dimensions (linear units) in something like meters or feet (since you are using a UTM projection, those would be meters), you do not need to use the Z factor to set a "scalar".  That "scalar" is only useful if your data are in a geographic coordinate system because then ArcGIS will also assume that your Z units (elevation values) are in the same units as the x and y (linear units) -- that is, ArcGIS will assume that your elevation values are in degrees!  So the scalar helps ArcGIS to make the conversion from degrees to either meters or feet (and it depends in where your study area is located north or south of the equator).

One other reason to use the Z factor to scale the data is if your z units (elevation values) units are different from your x and y units.  This might happen if you have data that has elevation in feet and you use a UTM projection, in which case the x and y units will be in meters, or you have data that has elevation in meters and you use a State Plane projection, in which case the x and y units will be in feet.

If none of these apply to your data, then you can use the Z factor to actually do what it is meant to do -- exaggerate the elevation a little, depending on your use case.

SOOOOO - for your situation, double check that the data you are using has z values in meters, then do NOT set a Z factor when you use the Swiss Hillshade Model -- your results should then be what you expect them to be.

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