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Thread: So what are the current sources for DEM now?

  1. #81
    Join Date
    Nov 1999
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    Jacksonville,, FL, USA.
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    3,804

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    That might be your problem. I've never heard anything good abouit "8" and
    the office where I worked part-time after I retired from CSX would not touch
    it with a long pole.

    Tell you what. Send me a private message and give me the coordinates of
    where you are downloading data (I like to use the coordinate box method
    and key in the rough coordinates, it is most precise) and then tell me the
    names of the files your are having trouble with. I will download them and
    see if I can successfully convert them and if I can, I'll ask for your email
    and send them to you by "WeTransfer".

    J. H. Sullivan

  2. #82
    Join Date
    Apr 2015
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    I actually got in touch with Sean, who is also willing to look into the issues. It seems like at least three of the six files seem to be corrupted via the USGS site.

    USGS 13 arc-second n44w073 1 x 1 degree
    USGS 13 arc-second n44w074 1 x 1 degree
    USGS 13 arc-second n45w073 1 x 1 degree
    USGS 13 arc-second n45w074 1 x 1 degree
    USGS 13 arc-second n43w073 1 x 1 degree
    USGS 13 arc-second n43w074 1 x 1 degree
    https://i.imgur.com/LPZNEX4.png

  3. #83
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    Nov 1999
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    Jacksonville,, FL, USA.
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    Shane,

    I thought I had a couple of corrupted files too, but then after I was more
    careful about protections, and running VTB as administrator they went
    fine. I would hope that someone else that is running Win-8 will notice
    this and see if they have problems. I know that there were a lot of
    issues in Win-8 and Microsoft did not have it out long before they came
    out with Win-10. Win-10 has some well known issues of it's own, the
    worst being the need to reload legacy software every time it does a major
    update. My supplier has confirmed this too and his clients have fits
    about it. They are all commercial operations, mostly small businesses
    for which he is effectively their "IT" man.

    J. H. Sullivan

  4. #84
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    Nov 1999
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    Jacksonville,, FL, USA.
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    Shawn,

    All 6 files processed without errors on my machine. I have a large zip file of the results
    sitting on my machine now and if you want it, I can send it via WeTransfer. I will need
    your email address so that a link will be sent to you as soon as the file is on the WeT
    server (which I guess is in Holland, there is where WeTransfer is based).

    Jerry

  5. #85
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    Apr 2015
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    Excellent, I will send you a PM of my email. This is very much appreciated. Curios as to why it simply kept having fits on my end. Eventually I will be upgrading to a new computer..
    https://i.imgur.com/LPZNEX4.png

  6. #86
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    With the thanks to Jerry for providing the geotiffs for DEMEX to work on. I finally got them sorted out.. kind of. DEMEX doesn't seem to want to merge the files correctly, so I had to do them one at a time, however, the result of the missing terrain... However, other than that, looks like I need to make a slight adjustment in the track heights to better match the terrain, and go through and redo some of the grades to better match. The best thing about 1/3, is most the terrain shows a bit where the tracks actually go, and from using the maps provided through TSRE, the are pretty spot on, maybe a slight off here and there, but nothing a small track section can't fix. I'm happy to get away from the poor resolution of HGST, because it just wasn't cutting it..

    Rutland Yard



    Rutland Yard/Price Chopper Shopping Center



    Center Rutland



    Florence
    https://i.imgur.com/LPZNEX4.png

  7. #87
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    Nov 1999
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    Jacksonville,, FL, USA.
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    Shawn,

    You can correct those steep valleys somewhat by tweaking the options in DEMEX. However, I have found
    that often the only way is to go ahead, bite the bullet, and download some .hgt files and use those in the
    areas where there are these steep ditches etc. As for adjusting the track height, I would adjust the
    terrain height, it is much easier. Use the elevation offset either + or -. Also, if you generate distant
    mountains, lower the DM terrain by approx. 20-40 meters otherwise you may get slivers of missing
    DM terrain - not really missing, just has a base too high above the standard terrain. In low mountains
    this value is more critical than in high mountains, so experimentation is needed.

    Jerry

  8. #88
    Join Date
    Apr 2003
    Location
    Silicon Valley, CA, USA.
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    Last year I downloaded a bunch of DEM files from the national map and using an open source program called qGIS converted the raster image I had downloaded to a (geo)tif format that DEMEX knows. No problems. I picked qQIS to do the conversion because it was free and also the easiest to figure out out to do the task.

    GIS software is usually quite complex and I'd guess I'm using maybe 1% of the functionality to do this conversation. It also let me merge raster images (just like DEMEX does) as well as slice out subsets. Usually I was merging one of those slices to a complete image in order to gain just that little bit extra so DEMEX could project to a whole row (or column) of tiles that otherwise would have been partially filled or ignored.

    The team that does qGIS likes to name each version after a European city. The latest version I know of is 3.12 (twelve) Bucharest.
    Dave Nelson

    Seldom visiting, posting less often that that.

  9. #89
    Join Date
    May 2010
    Location
    Cottage Grove, OR
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    75

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    Greetings everyone!

    I just posted a new announcement about DEMs... the "Old" dems that we used to download... You know... the 10 meter 7.5 minute dems... You just might want to read this...

    https://www.trainsim.com/vbts/showth...20#post1968120
    "FREE is a very good price!"

  10. #90
    Join Date
    Aug 2002
    Location
    Poteau, OK, USA.
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    This is wonderful news, Dale!

    Your considerable effort on this is nuch appreciated by this old head.

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