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What are appropriate pixel resolutions for DEMs based on source map scales?

August 13 2008 | 0 comments
Categories: Map Data

I have searched the Internet for hours trying to find some documentation or research describing DEM (output) pixel resolutions that are appropriate for different scales of topo source maps (input, digitized vectors used to generate the DEM). My gut feeling is that, because of inherent errors/limits in paper map printing, relative map accuracies (X,Y,Z), etc. there should be constraints on the output pixel resolution of a DEM based on the scale of the source topo map. For instance, I expect it would be inapproprate to create a DEM with 5 meter pixels from vector contours digitized from a 200K map. I assume there should be some correlation between the scale of the source maps and the output DEM pixel size but haven't found any info.
BTW I contacted ESRI support and was pointed to: http://blogs.esri.com/Support/blogs/mappingcenter/archive/2007/07/03/choosing-an-appropriate-cell-size-when-interpolating-raster-data.aspx
but most of this discussion relates to creating DEMs from point data and what the DEM data is being used for. I am hoping to find a formula or conversion factor that I can relate to any scale source map, "If the source map scale is "1:X" the pixel size of the output DEM should be between "Y" and "Z" map units.

Thanks and regards,
Rick

Mapping Center Answer:

Good question (and you're right about the reference to the earlier post, as it was about cell size selection for depiction of an analytical surface), and one that I'd been meaning to write up a as a blog entry.  So, here's a draft:

For raster elevation data here are my recommendations* for common resolutions, map scale ranges, and output media:

Print Media, e.g, ~300 DPI

Pixel SizeLargest ScaleSmallest Scale
~2m1:2,0001:10,000
~5m1:9,0001:24,000
~10m1:24,0001:100,000
~30m1:100,0001:250,000
~90m1:250,0001:500,000

 

On screen maps, e.g., 96DPI

Pixel SizeLargest ScaleSmallest Scale
~10m1:10,0001:300,000
~30m1:250,0001:500,000
~30m1:250,0001:500,000
~90m (SRTM)1:500,0001:18,000,000
~2min (ETOPO2)1:18,000,000None

*These recommendations are just a place to start; different symbology and media requirements will impact any specific solution.

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