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Author Topic: Any way to fix missing contours ?  (Read 1401 times)

vt.flatlander

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Any way to fix missing contours ?
« on: April 30, 2016, 09:12:50 AM »
I completed a topo of New Hampshire but I am less than happy with the fact that some parts of the map have 20 foot contours lines that just dead-end. The original TNM data is not as nice as I would like it to be and there is no State data set that I could find.
See attached.
Is there some method to fix this?

-Oz-

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Re: Any way to fix missing contours ?
« Reply #1 on: April 30, 2016, 11:47:05 AM »
What you are seeing is a break in grids. For 1:24k contours the USGS determined the appropriate interval in a 7.5 minute grid (I believe). At the line the contour interval can change.

If you want perfect contours you can download the DEM elevation raw data and generate your own. At that point you'll pick one contour interval for the entire state. The old maps/old tutorial (the data is still there) did it that way; with the contour lines available I choose to accept the "ending of lines" to have a varying contour interval across the state.
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popej

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Re: Any way to fix missing contours ?
« Reply #2 on: April 30, 2016, 04:23:25 PM »
I am less than happy with the fact that some parts of the map have 20 foot contours lines that just dead-end.
IMHO this looks good, better than full contours that can make a clatter. On my map I sometimes switch contours interval depending on height, this makes less clatter in mountains, but the solution on your picture seems to be more refined.