# Calculate the distance between two contours

I have two contour polylines (single shapefile) and I would like to calculate the mean, min and max distances between the two lines. Is there a function in ArcMap 10 (ArcInfo license, incl. Spatial Analyst) that will do this for me without have to use the measurement tool manually? The measurement should account for the curvature of the earth.

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What level of licence do you have for ArcMap (View, Editor, Info) as not all tools are available in all licences? – MappaGnosis May 10 '12 at 11:01
(1) It's unclear what you intend by "account for the curvature of the earth." Could you explain? (2) There are at least two different distances. To illustrate, pick one of the polylines as the base. Zonal statistics of the Euclidean distance grid for the base polyline, using the other polyline as the zone, may be what you are looking for. Reversing the roles of the polylines in this calculation will give (slightly) different results. – whuber May 10 '12 at 15:28
Just a thought but could you take one contour and buffer it incremental distances starting with one small enough that no part of the buffer touches the other contour. If during each increment you test with an intersect how much of the other contour is inside the buffer then when the buffer starts to touch you have the minimum distance and when it first includes the whole other buffer you have the maximum. Perhaps the "mean" is when half the length is intersected. – PolyGeo May 11 '12 at 0:34

What I could understand from your question is that you want to get a profile from contour polylines. I dont know if a zonal mean over the contour line works for you but it is a good idea take a look Spatial Analyst Zonal tools.

And another way, Easy Profiler2.1 - Generate Profile From Contour can help you too.. you can find it in ArcScripts here.

And I want to say before forgetting, you can find more profiler under ArcScripts.

The Main Function are include:

1. Generate Profile by a drawing Polyline on the Display.

2. Generate Profile by a selected Polyline in the Active Theme.

3. You can get "X","Y","Z","D" fields in the new Profile theme.

4. Where "X","Y" are the real coordinate,"Z" is the elevation,and "D" is the distance from corssing point to start point of profile line.

5. Draw Profile from "continuous" Point Theme.

I hope it helps you...

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That is a good idea, conceptually, but I am unclear if the zonal mean is actually what I need. The contours are over 1000 km long and I would like to know the mean, min and max as these are not elevation, but trait frequency contours. – Keith Larson May 10 '12 at 12:19
can you look at Zonal Statistics as Table (Spatial Analyst) in here – Aragon May 10 '12 at 12:46
looks interesting, my trait data is continuous and values have six decimal places. I am interested in these statistics for 0.1 intervals. Any ideas? – Keith Larson May 10 '12 at 13:12