TransDEM terrain request?

jrcrawford4

Poor & Needy
I was wondering if one of the TransDEM owners out there wouldn't mind generating a smallish .gnd file for me to use in TS12 if I could supply the DEM files and Tiger lines and topo maps. Please reply here or PM. Thanks.
 
Why don't you purchase TransDEM yourself? It's only $33 US and it's worth the investment. The learning curve is not as steep as you think. If you have any questions, feel free to post here or PM me. I can help you and many other can as well. As mentioned the program is well worth the investment and then some.

Having said this, I'm not pushing off your request; it's just easier for you to generate your own Trainz files. The reason mainly is today the NGS supplies 1 arc-second slices and the downloads are huge. Determining exactly what you want is also very difficult and these files can be quite large even if we could generate your exact map due to the higher fidelity of the downloads generated today.

TIGER information, is no longer used and I'm not even sure if it is available. What you would receive/download via TransDEM are actual images from the NGS map tile servers. You can choose between orthographic images or topographic maps including the historical ones for most areas of the country.
 
Thanks; it's not that I'm unwilling to buy it but, without going off on the details, now's not the best time. I appreciate the difficulties you mention; and no argument here about the versatility of the program. Partly, as this is a relatively small route, I can't quite decide if using the actual terrain is better or if it's better to just shape the terrain myself - the old model railroading practice of compression has definite advantages.

Thanks for the offer of assistance and the pointers. I did wonder about the feasibility of the terrain slices and whether or not DEM files would be practical (as they once were) or if everything now uses NED or something else seamless. Incidentally, TIGER info is still available from http://data.geocomm.com/dem/demdownload.html. That being said, if there's a better way, I'm all for it. I actually think the most useful overlay will be the historic topo maps and have already downloaded those from USGS.

It sounds like the best thing to do will be to start by hand and see how it goes. Thanks again; I'll definitely get in touch when I get started with TransDEM.
 
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DEMs are very practical but you need to chop them up in TransDEM. The NED is now a seamless server and this is a big part of the problem. A couple of years ago one could download a tiny slice, square, or nearly anything of any size, but then they upgraded to the new servers and now we have giant files. Each download is no less than 70MB it seems. I'm currently downloading one that is about 540 MB and then I'll cut what I want out of it in TransDEM. It's worth noting that TD now supports historical topographic maps and imports the information directly, via a third-party package, from the Adobe GEOPDF files located up on the NEGS map server. This is extremely helpful as the maps are placed directly, in place, on top of the underlying DEM with no fudging needed. This is done using UTM coordinate info that's embedded in the PDF and from the DEM.

Thank you for the information on the old TIGER maps. These weren't available for a short time, perhaps they have been updated. Keep in mind that they are not as accurate as the topographic images downloaded from the NGS.

The alternative to hand creating terrain is to use the old HOG program. I can't recall where this comes from, but this program will generate terrain from DEMs downloaded and manipulated in MicroDEM. This is an older method that does work, albeit, it's not as accurate since the DEM information is at a much lower resolution.

John
 
I used to use HOG/MicroDEM quite a bit - you could make seamless terrain along baseboard joins but you had to use a big "square" slice of elevation data to do it. It made for very large files, although HOG would trim it pretty well. I just used the TIGER info for that trimming (before that, I used digital line graph files) and for basic placement of track. As long as you had that color (teal?) for the track line in MicroDEM, you could get HOG to trim out any boards that didn't have it. But as you say, it wasn't always accurate and sometimes you'd discover that some place you'd expected to model had been trimmed out because of missing data in the TIGER file.

Don't know if HOG is still available or where to find it; I tried using an old .gnd file I had used it on and it messed up all the surveyor grid lines when I opened in Surveyor. Also ran into the old problem of hitting "undo" and losing minimap overlay. The new Surveyor grid is impressive in that it is more accurate to finer resolution height data (5m I think it is now?). TD sounds like a great program - being able to assemble all the info in one place and especially using the historic GEOPDFs. Much more powerful and flexible than HOG. No fudging is good! :)

Should you need it, the URL for TIGER, DEM, and other related files is here: http://data.geocomm.com/dem/demdownload.html. Organized by U.S. State and County - you have to register (free) and then you can download for free. Don't know how up-to-date the file formats are; there are TIGER files going back to 2000.
 
If you already have the historical USGS topo map, the Longitude and Latitude coordinates referenced in each corner can easily be applied as georeference points to place the map precisely on the 1x1 degree generated DEM map in TransDEM as an overlay (which can be applied to the Trainz map). The DEM map can then be whittled down to the applicable area. USGS maps from the USGS 'Historcal' collection are best downloaded at 1:24000 scale, which are commonly known as 7.5 Minute Quadrangle maps. Those maps downloaded from the site generally have embedded georeference data, which allows them to be automatically placed on a relevant DEM within TransDEM, with a simple button click
However, be aware that Dr. Z, the creator of TransDEM, frowns upon distributing bare Trainz maps. I'm sure you can understand why.
 
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