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#1
Jason JB

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Hi Everyone,

I've been working with a lot of elevation data recently and I have come across a lot of literature and information about interpolation techniques and the sort but I was wondering if there's certain criteria with regards to interpolation cell size
of contour data and vice versa (extraction of contour data from elevation models).

For example, what is the optimal cell size for creation of DEM's from 20 metre interval contours and if I have Digital Elevation Models with 30m cells, what would be the optimal contour line interval. I'm just hoping to get some feedback on what rules are used with regards to this.

Thanks in advance!

#2
aug_aug

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I think you're going to find out that you can make the lines or cells as small as you want, the only thing to keep in mind is that the underlying data is only going to be as good as the cells (30m) or interval (20m) that you create your new map from.

So, you could take the 20m lines and make .5m cells, and it would turn out just fine and look good, it's just that the values are all going to be interpolated from 20m contour lines. Basically you can't go any higher in resolution than the best data you have to start with.

I'm rambling -- but essentially, as far as I know there's no formula for creating cells or contour lines, but you must keep in mind that people who are looking at your 1m contour interval may not realize that the lines were derived from 20m data and therefore not as accurate as you are portraying them to be.

Hope that helps and makes at least a little sense.

#3
Brandon Tourtelotte

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In EVC's experience, a good rule of thumb is to couple these parameters:

5m = 2.5m contours
10m = 5m contours
30m = 10m contours
50m = 20m contours
90m = 40m contours
150m = 80m contours (roughly speaking)
Brandon Tourtelotte
East View Cartographic, Inc.
Minneapolis, MN




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