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Author Topic: Noob with Dem2Topo Question  (Read 5010 times)

Steveor

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Noob with Dem2Topo Question
« on: May 30, 2008, 09:11:47 PM »
I'm attempting to make an Afghanistan topo map to overlay the road map already in GPSFileDepot's library.  I'm using using USGS SRTM 90m data.

My problem is once the data is processed by Dem2Topo and uploaded into MapEdit there is a thick horizontal straight line made up of all the contour lines that intersect the top edge of the tile.  I realize this is a known Dem2Topo issue but is there a quick way to edit these out?
« Last Edit: December 20, 2009, 04:39:51 PM by Coggins »

-Oz-

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Re: Noob with Dem2Topo Question
« Reply #1 on: June 02, 2008, 01:40:54 PM »
The only thing I can think of is to use MapEdit and when you export it crop the top part of the map off.  I'm not sure if its a square though or if you'll lose part of afghanistan.

When contour intervals are you using?
Dan Blomberg
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Steveor

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Re: Noob with Dem2Topo Question
« Reply #2 on: June 03, 2008, 07:46:57 PM »
I'm using 20m contour intervals and each map tile looks like they'll be pretty big.  Not surprised considering each area is the size of an average sized state. 

The sections to crop off are pretty uniform.  Some start on the top, some on the side depending on where the major contour intervals first touch the side while going through Dem2Topo.  I guess I'll just have some 200m wide empty bands of contour data.

Incidentally from looking at the data from your Afghanistan map and one Ibycus sent me I determined the $250 version of the Afghanistan map uses the exact same data which is freely obtained from an Afghani government GIS site.  They don't even clean up some of the meaningless street labels.  Very glad I didn't pony up the dough for something I got for free.  Thanks again.

-Oz-

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Re: Noob with Dem2Topo Question
« Reply #3 on: June 15, 2008, 05:06:20 AM »
Steve,

Have you completed the contours.  I have written a program that creates contours from tif files.  Its not fully complete but its good enough that if you wanted to use it to not have this problem with the long problem lines it could help you with that.

Dan
Dan Blomberg
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Indrid Cold

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Re: Noob with Dem2Topo Question
« Reply #4 on: April 27, 2009, 01:00:10 PM »
I checked this data source and there are voids where some of the dem files meet, that's why Dem2Topo and other software is returning results like this. (see attached graphic).

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Re: Noob with Dem2Topo Question
« Reply #5 on: May 07, 2009, 05:17:30 PM »
That is an annoying gap...
Dan Blomberg
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