DEM Help

Q

quakers1

Stuck With a Bad Username
Hello everyone. After taking a break, I am back and ready to start on my next route. I am wanting to use a DEM, but I am not going to request one to be made. I am wanting to take on the challenge and make the DEM myself. I am not completely sure how to make DEMs, so I could use some help. I am wanting to use MicroDEM, so any other program is out of the question. Is it possible that you guys could help me out? Is there any tutorials out there that may help? I thank you advance for any help.

-quakers1
 
G'day quakers1,

As far as I can tell, the only major difference required for the newest version of MicroDEM from the instructions referred to above, is the need to use an external Graphics Manipulation Program to convert the exported *.tiff file into *.tga format. The new MicroDEM exports in native *.tga format (which is something I wish my own preferred Global Mapper would do). Otherwise Wewain's instructions should be followed as is...

Jerker {:)}
 
MicroDEM and HOG

Thanks for all of your help. I downloaded MicroDEM and HOG last night. But, I don't think Wewain gave a link to the US seamless data server. Do any of you all know the link to it? And one more question. Does making DEMs require both MicroDEM and HOG, or do you just use one or the other? I have both HOG and MicroDEM, but I am unsure if I need both to make DEMs. I'm going to try to make a DEM I've been wanting for awhile, and I'm sure some of you may know what it is. I thank you in advance for any help.

-quakers1
 
G'day quakers1,

Not being 'local', I cannot recall the address exactly but I do remember that the 'acronym' "usgs" dot "something or other" (perhaps ".gov") will get you close (hang about a bit longer and someone who does know will be more specific, I'm sure). As for the other matter, you do, indeed, require both programs. MicroDEM 'creates' the data that is used by HOG to create the Terrain...

Jerker {:)}
 
Not Ready To Give Up

Well guys, I tried to make the DEM following Wewain's instructions, but I was not successful. But, I'm not ready to give up and start asking for someone to make the DEM for me. I am not going to let all of the data I downloaded go to waste. To me, Wewain's instructions seem very outdated. Is it possible any of you guys here could give me up-to-date, step-by-step instructions on how to make DEMs using MicroDEM and HOG? I thank you in advance for any help.

-quakers1
 
Hey HiBaller

I just looked at it. It's pretty clear, but, I am wondering how to merge the multiple DEM files I downloaded from http://data[URL="http://www.geocomm.com"].geocomm.com[/URL] into one DEM. The exact files I downloaded are the Harrisburg West, Harrisburg East, Hershey, Palmyra, Lebanon, Richland, Womelsdorf, Sinking Spring, Reading, and Temple DEM files. I also downloaded the TIGER data for Dauphin, Lebanon, and Berks County. I need to merge all my DEM files so I can have me one big DEM file. But I'm unsure how to do this.:confused:

-quakers1
 
On the top of the MicroDEM screen there is a tab marked "In/Out". Without loading ANY DEM maps, click this and go to the Merge -> Pick Multiple menu entry. Choose the maps you wish to merge into one map and then click OK. This will merge them into one file.

I might caution you though with this: Merging as many as you want to merge will create a HUGE file. When you expand it further to create the bitmapped final DEM it will grow even larger. I would suggest that you merge two, or maybe three, and make one DEM. Then, merge two or three again and make a second DEM. Once they are both created, make two new routes in Trainz (one for each part) and then, after your get them into Trainz, merge them using Trainz itself.

Bill
 
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Ok, I put all the files in order, and I tried to merge them. Here is the text message I got on both the Harrisburg DEM files.

"Incorrect datum; not included in merge"

What should I do about this?

-quakers1
 
Hi Bill, Q1

The 'DEMs' Quaker is downloading are USA 'Quads', not full-sized Dem files as found on the NASSA etc sites. I wouldn't try many more than 10 at once, but merging 10 shouldn't be a problem, although it will take microdem a few seconds to save the file (might even look 'frozen' for a moment)...

Andy :)
 
It's been a few years since I used MicroDEM. I can't remember whether MicroDEM would be able to re-project coordinate systems or shift geodetic datums or the the fly. To avoid any risk, make sure all files to be merged are in the same coordinate system and based on the same geodetic datum. The coordinate system you want will be UTM and the geodetic datum WGS84. Some of the US DEMs are already delivered as UTM/WGS84 but those downloaded from Seamless Server will be in Plate Carrée pseudo projection, i.e they will have lat/long coordinates. MicroDEM offers all the necessary conversion/transformation functions.
 
Hey Andy, I'm only merging 8 of them, so it should not be a problem at all.:) Oh yeah, do you know how to fix the problem I have. I posted what the problem was in my reply above yours. If I can get it straightened out, I'll be on my way.:) I thank you in advance for any help.

-quakers1
 
Q1 I have merged the same area. You have picked the worst possible area for a first attempt because you have quads from different 'zones' in your merge and - silly as it sounds - North is not in the same place for all your files.

You need to convert all references to lat/long, which gets a bit tricky.

Alternatively if you can give me 48 hours, I will upload a truly huge bare-boards DEM route which I am pretty sure includes the area you want to model.

A word of warning tho - the lat/long conversion results in imperfect terrain and poor DEM/Tiger alignment....

Andy
 
Slightly Off Topic

Hi Geophil - there is a thread in the forum where you and I discussed my problems with this very same project. I have searched in vain, but can't find it. Your memory may be better than mine, any recollections?

edit - FOUND IT - see below :)

Andy
 
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Hey Andy...

Go ahead and upload that DEM. But, is it possible you can add the TIGER data to the DEM? I'll lop off what I don't need. And if you upload it, Andy, will it be to your site?

BTW thanks for hosting Sureshot's NS C40-8s Andy! I sent a PM to Sureshot at the RRMods forum asking if I could host his NS SD70M-2s, NS GP60, and NS MP15DCs at my site. I'm waiting for a reply.

-quakers1
 
Quakers this thread describes your problem and the fix.

Let me know if you want to work it through yourself or grab my route.

Couple of points -

(1) working it through would be a worth-while project, if you can do this one you have mastered TransDem and

(2) my blank route is huge - deleting out the boards you don't want will take as long as doing it the hard way

Let me know....

andy :)
 
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