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hypsometric tinting and different color ramps for arid versus humid

January 06 2009 | 3 comments
Categories: Symbology

I've been trying to figure out how to accomplish a shaded relief where Death Valley doesn't look like a lush forest. I came across an article by Tom Patterson http://www.shadedrelief.com/hypso/hypso.html that describes how to accomplish this task using Photoshop, but I don't have Photoshop and would prefer to do this in ArcMap. Do you have any suggestions? I've tried overlaying two different color ramps with 50% transparency each but the effect isn't what I'm trying to achieve.

Mapping Center Answer:

I think the best way to do this is to create a new elevation grid just for the Death Valley area and apply a unique color ramp to that grid. This will work if you use elevation to define the extent of Death Valley.

The trick then is to make the color ramp for the Death Valley area have the same color for the elevations along the edge as the elevation for the larger grid. You can use the Eyedropper tool to find the color of the cells in the larger grid that were located along the edge of my lake grid.

Let me know if you need more details, and I can publish more detailed instructions.

not just Death Valley but also the Sonoran and Moj posted by Thomas Dilts on Jan 7 2009 10:22AM
The problem isn't just Death Valley, however. Other parts of the Sonoran and the Mojave look green and lush, or if I use browns the Central Valley of California looks like a desert. I've tried using two color ramps for the "arid zone" and the "humid zone", but need to find some way that blends them seamlessly. One approach that I've thought might just involve using the 2001 NLCD land cover data instead of elevation and precipitation as color ramps.
The trick is in the blending posted by Aileen Buckley on Jan 7 2009 10:31AM
Yes - the big trick to all this is the blending of colors along the edges, which is why I suggested using elevation to "clip" the Death Valley area - I can't think of another method that will work. If you can find a way to create separate grids based on a clean elevation break, you can "blend" at the edges of the grids by using color ramps that have the same colors at the ends.
Natural Earth posted by Aileen Buckley on Jan 7 2009 10:33AM
You can also download Tom Pattereson's Natural Earth data from: http://www.shadedrelief.com/natural2/index.html. He did a lot of this work for you and you can use these data directly in ArcGIS.

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