Them *#&@&%^! DEM's!

I am currently working on the Santa Fe Chillicothe sub-division (Chicago to Fort Madison, Ia.) around the 1985-86 time frame. I decided to dl' the DEM's and go with that process. I got all the DEM's I needed for the sub-division and began the merging process
( as per the DEM tutorial by Ted Curphey ). I got all the DEM's merged together down to just 2 files, for some reason it wouldn't let me merge them all together at once. I am using Microdem/terrabase 5.1.
But it just won't let me merge the last 2 files together to get my "main" file so that I can git to the extraction phase.
I've come close to tossing the 'puter out the window but i've held back from that so far.
Anyone have any suggestions on this?
I downloaded the DEM's all in 30x30 res., but I just can't figure out what the problem is now.
Any help would be greatly appreciated.RichSanta Fe all the way!!!!

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RE: Them *#&@&%^! DEM's!!!!, Motley24Crue2, Oct-16-02, 05:46 PM, (1) RE: Them *#&@&%^! DEM's!!!!, cnr29910, Oct-16-02, 05:50 PM, (2) RE: Them *#&@&%^! DEM's!!!!, Motley24Crue2, Oct-16-02, 05:53 PM, (3) RE: Them *#&@&%^! DEM's!!!!, cnr29910, Oct-16-02, 05:57 PM, (4) RE: Them *#&@&%^! DEM's!!!!, LawrenceKellie, Oct-16-02, 06:07 PM, (5) RE: Them *#&@&%^! DEM's!!!!, cnr29910, Oct-16-02, 08:38 PM, (6) RE: Them *#&@&%^! DEM's!!!!, davidbeach, Oct-16-02, 08:43 PM, (7) RE: Them *#&@&%^! DEM's!!!!, JohnCS, Oct-16-02, 10:22 PM, (8) RE: Them *#&@&%^! DEM's!!!!, cnr29910, Oct-17-02, 06:46 PM, (9) RE: Them *#&@&%^! DEM's!!!!, cnr29910, Oct-19-02, 07:53 PM, (10)

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any error messages?
Bob
Philadelphia, PaCurrent Project Northeast Corridor Philadelphia Subivision, Zoo Interlocking started

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Yes, the error message I get says Incorrect digitizing datum; not included in merge.I dunno!RichSanta Fe all the way!!!!

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i have run into that a few times, sometimes the files contain errors in them, in my case Allentown west, pa had errors there are supposed to be 19 files in the zip... there where 26, so i had to unzip that file and copy all the files that are alike into a Separate folder and then continue with the merge
Bob
Philadelphia, PaCurrent Project Northeast Corridor Philadelphia Subivision, Zoo Interlocking started

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Well, I know I don't have errors like that, cuz I unzipped all of the DEM files that I downloaded into a temp folder, then started the merge. So if there was any alike files, I would think it would tell me before unzipping the file into the temp folder I.E. asking me if I wanted it to overwrite the file.It was easy to get to this point once I started, now I feel like I'm at a dead end.Rich

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First, do not unzip the files. Those files have to be in a particular format, and unzipping them *can* change that format. Microdem can work with the *.gz files. So you might want to give a try with the compressed files. This is one of two major problems that your symptoms sound like.The second is that some DEM files are corrupt from the source. That just happens, and there is nothing you can do about it. If that is the case, try downloading again the file that is giving you problems. If that still doesn't work, and if a 10m exists for that file, download it and then merge.Another problem, but I don't think this is the problem you are having, is that Microdem does have a finite limit to the number of DEMs it can merge. When you hit that limit, it won't merge any more. However, as I said above, I don't think that is the problem here.BTW, the creator of Microdem has a Delphi forum for users. If what I have written above does not help, you might want to try there. It can be found at: http://forums.delphiforums.com/microdem/startLawrenceLawrence

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I am re-downloading the files over again but this time I am dl'ing the 10 meter files where I can, the rest 30 meter files. When I get these I'm gonna do the merge thingy again and see what happens.RichSanta Fe all the way!!!!

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DEMEX can do any DEM merging you need to do. Don't use Ted's tutorial. It was great when it was written, but it is several versions of DEMEX old now. The instructions with the current version of DEMEX are quite good, and there is supposedly a tutorial for that current version at the web site (haven't needed to even look for it).David Beach.Palouse & LewistonRoute Building 1% Completed
Route Mapping 10% Completed

Standardized \global\tsection.dat file now at build00010.

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In certain instances Microdem doesn't like merging dems which were created with different geographic reference datums (USGS uses alot of different datums in adjoining dems depending on who did the digitizing and what the source was).David Beach's comments are accurate IMHO. For the highest efficiency merge what dem's you can in Microdem first and save in Microdem DEM format, then merge the larger blocks using DEMEX (if that is your software of choice).

JohnCS
dem_ex@hotmail.com
visit the DEMEX website:
http://www.dem-ex.com

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Man I wish I knew that last night. I deleted the merged files I had and started over. At least I know this time though. I'll merge the files that DEM will let me merge then I'll tackle the reest with DEMEX. I should have the most recent version of that since I just dl'd that a couple of days ago. Thanks guys!!!Rich
Santa Fe all the way!!!

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Well this is what I did, After dl'ing all the DEM's I needed, I merged the zip files instead of uncompressing them. I was able to merge all of the zip files into 2 "main" files. Then used DEM-EX to extract them into the tiles for my new route. It worked perfectly!
I now have terrain created from DEM to start laying tracks on. After having to go through this on trial and error, I found it relatively easy once you realize what you have to do with DEM files and DEM-EX.
It can all be very simple once yougo through it the first time.RichSanta Fe all the way!!!

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