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C_130_Herc (18 posts)
Nov-11-01, 10:44 AM (EST) "another post for help on DEM's (DTED-0)" ok, first time i've played about with DEM's, so i guess i'll be classed as a newbie(gotta start somewhere!). Problem = i've got some DEM's of the UK, in DTED-0 format, and after reading a load of strings on these forums on using DEM's for terrain mapping, i thought i'd have a go at it, armed with a copy of MicroDEM and (finally, took a while to find a url for the d/l) a copy of DEM-MSTS. ok, *thinks* "gotta change these from DTED-0 to UTM, no probs!, i remember the routine from the forum strings". Well, i remember the conversions to go thru, DTED-0 > DTED-1 > UTM etc. so here goes... convert to DTED-1, fine, convert to UTM... "can't create UTM from spherical DEM's!"... WTF!?!?!?, ok, try again, and again, try different conversions, after a few general protection faults which kindly closed MicroDEM, and lots of the spherical error msgs, time to find a nice hard wall to hit my head on, but first, plead for help on the TS.com forums, so here goes..... "please please please please please please please please please please (maybe even pretty please with a cherry on top) can someone give me some directions/instructions on what to do so i can stop this headache-inducing activity using the wall and make a start on my route, i've got the tiles all laid up ready to roll too! when i manage to get the route done and published, anyone who has helped me in any way will be getting a GREAT BIG thank you included in the route files (if that ain't an incentive, i dunno what is! hehe) Alert Edit | Reply | Reply With Quote | Top
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Subject Author Message Date ID RE: another post for help on DEM's ... C_130_Herc Nov-11-01 1 RE: another post for help on DEM's ... rtj Jan-09-02 2 RE: another post for help on DEM's ... wdperson Jan-09-02 3 RE: another post for help on DEM's ... rtj Jan-09-02 4

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C_130_Herc (18 posts)
Nov-11-01, 12:25 PM (EST) 1. "RE: another post for help on DEM's (DTED-0)" problem solved, well mine is, here's a post i found with a different technique for converting DEM's to UTM format...This is a step-by-step HOWTO that explains how to generate terrain for a MSTS route from freely available DTED-level 0 data, in the hope it can spare someone the hair-pulling I went through. It worked for me for a part of France, but it doesn't mean it will work for every other region of the world (and it probably won't). I'm not even sure that I haven't made a mistake somewhere, because DTED-0 resolution is not enough to generate a recognizable terrain. DEM specialists, please correct me if I'm wrong...
First you'll need:
-a MSTS route, generated as per instructions of the MSTS route geometry extractor help files
-the geo data tool named MicroDem (available from http://www.nadn.navy.mil/Users/oceano/pguth/website/microdem.htm)
-the ll2utm.exe utility (available from http://www2.chem.elte.hu/gigant_club/msts/)
-the DEM-Extractor utility (available from this site's file library, do a search...)
Here it goes:-I get my DTED data from the NIMA GeoSpatial engine (http://geoengine.nima.mil/). There are other sources of DTED-0 data, but this one is great because it lets you graphically select the region you want data for.
So, once you're there, zoom to the area of interest on the map (making sure your MSTS route is totally covered by the selected area), select the "Download/Order" tab. Under "DTED" make sure "Military specification" is selected as format, "Windows" as platform, then click on "Download". The egine starts to prepare your file. After a while, you'll be able to download it, it's a zip file named something like DTED0123456789.zip.
Save it somewhere, unzip it, you'll get a set of *.dt0 files (among others, but those are the interesting ones) in the "dted" subfolder -Using MicroDem->"In-Out"->"Merge"->"Merge DEMs", merge all *.dt0 files into a single DEM file, say terrain.DEM. -Since this DEM uses lat-lon coordinates, MicroDem refuses to export it directly to ASCII XYZ UTM, so export it to ASCII XYZ lat-lon using MicroDem->"In-Out"->"Export"->"ASCII XYZ, full DEM"->"lat-lon".
The result is a file, say terrain.LL.XYZ, about 10 times bigger than terrain.DEM, that looks like this:
48.000000 4.000000 170
48.008333 4.000000 163
48.016667 4.000000 149-Now use the ll2utm utility to convert this file to UTM, using the DOS command prompt: "ll2utm -d < terrain.LL.XYZ > terrain.UTM.XYZ"
The resulting file is about the same size as the previous one, but it looks like this:
574595.1 5316784.0 170
574583.1 5317710.2 163
574571.1 5318636.4 149-If you try to feed this file as-is to the Dem-Extractor utility, it will give you the following error message: "Invalid XYZ data format or order". For some reason, as I learned somewhere on this forum, the DEM needs to be "gridded" first, whatever that means.
Do the following:
* MicroDem->"In-Out"->"Import"->"ASCII XYZ", select terrain.UTM.XYZ.
* In the "ASCII XYZ import parameters", leave everything as-is, click OK.
* "Center long. for UTM zone", leave 0, OK.
* "Header" window, XY units, enter 100 for "X space" and 100 for "Y space", then OK
* "Verify X spacing", OK, "Verify Y spacing", OK
* "Header" window (again), click OK again
* MicroDem creates a huge file terrain.UTM.DEM (several Mb)
* still in MidroDem's "Data Manipulator" window (In-Out), select "Export"->"ASCII XYZ, full DEM"->"UTM"
* open for input the DEM just created (terrain.UTM.DEM)
* save as terrain-g.UTM.XYZ-Now you can use terrain-g.UTM.XYZ with DEM-Extractor!Granted, the generated terrain is neither smooth nor realistic, but it's a better work base than plain flat green tiles.All feedback is appreciated.Cheers,
Olivier
.................................................................
Well, there you have it, worked a treat, no probs at all
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rtj (2 posts)
Jan-09-02, 09:32 AM (EST) 2. "RE: another post for help on DEM's (DTED-0)" Hi, I'm new to all this ... so please excuse etc. I want to use DEM data for use in the UK (just south of Bath on the old SD&DJR line) I'm looking for the program DEM-EX but cannot find it anywhere. Has anyone got the URL please?Any other comments or help would be welcome. The programs seem devilishly difficult and confusing!!BWRichard Remove | Alert Edit | Reply | Reply With Quote | Top
wdperson (35 posts)
Jan-09-02, 10:47 AM (EST) 3. "RE: another post for help on DEM's (DTED-0)" >Hi, I'm new to all this
>... so please excuse etc.
>I want to use DEM
>data for use in the
>UK (just south of Bath
>on the old SD&DJR line)
>I'm looking for the program
>DEM-EX but cannot find it
>anywhere. Has anyone got the
>URL please? easiest place to get it is http://sd40.topcities.com. Click the link DEM-EX (first option).>Any other comments or help would
>be welcome. The programs seem
>devilishly difficult and confusing!!
>
>BW
>
>Richard
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rtj (2 posts)
Jan-09-02, 11:08 AM (EST) 4. "RE: another post for help on DEM's (DTED-0)" Hi,I'm modelling the Uk as well. Just 15 miles of the S&D south of Bath. What in your opinion is the best source of DEM data?Thanks,Richardplease cc to rtj@mac.com Remove | Alert Edit | Reply | Reply With Quote | Top

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