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Geo Data - USA
https://forum.transdem.de/viewtopic.php?f=8&t=20		 Page 4 of 5
Author:  geophil [ 17 Jul 2013 10:33 ]
Post subject:  Re: Geo Data - USA
Garry,

the 1x1 degree chunks are related to the retirement of Seamless Server. It's all prefabricated now. USGS claimed it's cheaper to operate this way.

See here for the latest info on this matter:
Data Delivery Updates, National Elevation Dataset (NED), July 1, 2013: Changes with the delivery of NED 1-, 1/3-, and 1/9-arc-second data
Author:  Green Eggs n Pelham [ 19 Jul 2013 00:08 ]
Post subject:  Re: Geo Data - USA
In the Trainz maps I noticed the waterways aren't "carved out". Is this due to the anomaly you suggested earlier GeoPhil about the depths being too large, and those parts of the DEM being lost?
Author:  geophil [ 19 Jul 2013 08:31 ]
Post subject:  Re: Geo Data - USA
Accurately modelled river beds, cuttings and embankments/high fills need high resolution DEM data, see the Comparison of USGS NED DEMs. For the result in Trainz Surveyor see the example here.
Author:  Green Eggs n Pelham [ 21 Jul 2013 02:28 ]
Post subject:  Re: Geo Data - USA
In order to get the most out of topography, in the menu below, do I check off anything besides elevation?

(After I've selected what area I want, I get a pop up menu with the following options)

US Topo
Historical Topo Maps
Structures
Transportation
Boundaries
Geographic Names
USGS Map Indices
Hydrography
Contours
Land Cover
Elevation
Orthoimagery

I've been under the impression that for Trainz, you only need elevation. I want to use 1/3 arc sec, but also some 1/9 arc sec for a DEM of NYC for a subway route--but I'm wondering if there are any other options I should check off in this list?

-A
Author:  Jerker [ 21 Jul 2013 02:52 ]
Post subject:  Re: Geo Data - USA
G'day Green Eggs in Pelham,

..."Elevation"...is the only option you should select from that list, -A...

Jerker {:)}
Author:  mrgisa [ 21 Jul 2013 03:16 ]
Post subject:  Re: Geo Data - USA
I could be mistaken, but transportation might be worth a look. You could get the rail line with it I think. Don't hold me to it, but try it out and see. Jerker is right (pretty much all the time anyhow ;) ) about everything else for sure though.
Author:  geophil [ 22 Jul 2013 18:28 ]
Post subject:  Re: Geo Data - USA
mrgisa wrote:
I could be mistaken, but transportation might be worth a look. You could get the rail line with it I think.
I have tested it now, you are right, you can get vector data this way. It takes ages to be produced (36 hours for my example). Select ESRI Shape format. The layer of interest is "Trans_RailFeature.shp".
Author:  mrgisa [ 22 Jul 2013 21:22 ]
Post subject:  Re: Geo Data - USA
In the past, before the changes from seamless, getting the transportation .shp file was very fast. I suppose things have changed. :/
Author:  Jerker [ 25 Jul 2013 15:43 ]
Post subject:  Re: Geo Data - USA
G'day Green Eggs in Pelham & mrgisa,

...in essence, here, guys, I was merely repeating the recommendations from 'the good doctor' in his instructions for obtaining the data, which I had generally followed 'to the letter' where it was necessary. Now that you have piqued my interest, a quick 'look into it' indicates that the vector data obtained by selecting the 'Transportation' layer, in *.shp file format (which TransDEM can read in as a route polyline), might well be useful as data to provide a much more accurate rendition of the route polyline (compared to anything any 'human' could provide - depending upon the accuracy of the data, of course). Provided that not every example takes 36 hours to download, it might be an alternative to the manual method (and the data might include all sidings, as well) - at least for US based routes...

...a better option than T.I.G.E.R. data, I suspect...

Jerker {:)}
Author:  geophil [ 26 Jul 2013 20:33 ]
Post subject:  Re: Geo Data - USA
Jerker wrote:
...a better option than T.I.G.E.R. data, I suspect...
Certainly. Remember, TIGER is only 1:160,000. What we get here looks like the 1:24,000 DLG we used to download in SDTS format, quad by quad. The meta should reveal the data source.

One day, I might be writing an OSM vector data importer for TransDEM. For the time being, JOSM is our best option if we want to get some of the best vector data available, selected locations, of course. Generally speaking though, 1:24k isn't that bad, not even for vector.
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