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ArcView - joining two sets of contours to generate a smooth DEM

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#1
Tommo

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Hey All

I'm trying to join together two sets of contours in order to generate one continuous DEM. The two sets are on 5m spacing and 2m spacing. I'm not sure of the best way to approach this as its new territory for me.

Can someone give me a few pointers?

All help is much appreciated.

Cheers
Tommo

#2
Martin Gamache

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Tommo,

You have several options IMO.

1. Generate the two DEMS from your two contour datasets at the same resolution. Merge the DEMS.

2. Get rid of half the contours from the 2m dataset and follow the advice in number 1.

3. Generate a DEM from the 2m data, derive contours at 5m, merge the 5m contours, then create one new DEM.

4. Generate points at constant intervals from all the contour datasets, merge all the points and interpolate a DEM from the points.

#3
Charlie Frye

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I would recommend Mosaic over Merge (ArcGIS Spatial Analyst extension), which allows you to choose how to manage what happens at the edge.

I would also recommend using the Spatial Adjustment tools in ArcGIS on the 5m contours; you'll be able to adjust or rubbersheet those contours to exactly match up. Plus, if you've got the time, you can always jump into the editor and snap every other 5m contour to the correct 2m contour in the other dataset.
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#4
Tommo

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Great guys - Thanks for the help.

Martin - I like the sound of generating points from all the contours. I'm assuming that there's an automated way of generating the points? This seems like the best initial approach for me as I have a few streams weaving across the border, and the lack of detail in one set of contours is making them run uphill! I suspect there might still be some manual editing to make things work out nicely though!

Thanks again,
Tommo

#5
Martin Gamache

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The best way to generate points is with Edit Tools Geowizard. That is the way I've done this in the past.

mg




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