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 Post subject: Re: Geo Data - Australia
PostPosted: 18 Apr 2013 16:43 
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Joined: 30 Jan 2011 13:03
Posts: 170
G'day geophil,

Yes. Indeed, Roland, when I 'unpack' the *.zip file using Windows Explorer, I see all six of those files in the list but they are all showing up as being 4,194,304 KB apiece and when I try to unzip them from there, the last two "w001001.adf" and "w001001x.adf" both completely disappear...

...I tried a further download of the file, which took a little over 3 minutes (at a fairly constant 350kB/sec - a good connection, dare I say) and the Firefox 'Library Dialogue' advised me at the end that I had downloaded the correct 80.8 MBytes. In Windows Explorer, the *.zip file showed up in the Properties Dialogue as being 80.7 MBytes but there was no change to the situation when I clicked through to the dem1sv1_0 folder. It all 'appeared' to be the same after 'extracting' the contents of the aforesaid folder to the appropriate place...

Jerker {:)}


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 Post subject: Re: Geo Data - Australia
PostPosted: 19 Apr 2013 20:02 
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Joined: 05 Jan 2011 16:45
Posts: 1463
Did you explicitly extract the files from the zip package? The Windows Explorer built-in zip utility does not do that automatically, one of the reasons I replace it with 7-Zip on all my Windows installations. 7-Zip doesn't extract automatically either, but it does not mislead you the way Explorer does.


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 Post subject: Re: Geo Data - Australia
PostPosted: 20 Apr 2013 16:24 
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Joined: 30 Jan 2011 13:03
Posts: 170
G'day geophil,

...as I mentioned in an earlier post, Roland, explicit extraction using 'Winzip' failed miserably because the trial version I was using had long since 'passed it's use by date' and Winrar produced the results shown in the first of my images above. As a somewhat 'desperate measure', I took you upon your word and downloaded and installed 7-Zip. You will be pleased to learn that it extracted the file without a hitch at the first attempt. I can now continue with the project that was being delayed...

Jerker {:)}


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 Post subject: Re: Geo Data - Australia
PostPosted: 20 May 2016 04:09 
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Joined: 30 Jan 2011 13:03
Posts: 170
G'day geophil,

I just thought I'd drop you a short note, Roland, to advise you that the NEDF has changed their website with a completely different approach to how things are done. The 'new' site is offering brand new 5 metre LIDAR based DEM datasets (seemingly for free through the Creative Commons Licence) but I fear there may be issues. They are also taking great pains to point out and to direct users to their new WCS and WMS download options, which might be useful. I haven't yet been able to work out the new process myself (much to my chagrin, as I have a project in the works that requires Australian DEM) but it would seem that you will have to alter the small tutorial at the beginning of this thread. I'll leave you to investigate the situation...

Jerker {:)}


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 Post subject: Re: Geo Data - Australia
PostPosted: 27 Aug 2016 07:47 
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Joined: 27 Aug 2016 05:00
Posts: 33
For small downloads, the LiDAR data seems to work fine. From the ELVIS portal, you can select a data set from DEM-S, DEM-H, LiDAR 5m and LiDAR 25m. I only was able to get TransDEM to accept files in the ESRI format, with the MGA94 coordinate system (apparently within a meter of being WGS84 and therefore close enough for the accuracy involved).

You can access the portal here: http://www.ga.gov.au/elvis/

While a small area worked fine for the LiDAR data, I found that downloading the high resolution data for the area I wanted did not work with TransDEM. Possibly too big a filesize? It was around 160 MB. For now Im working out the tool, following the tutorials... but the small bit of LiDAR data looked like its something I want if at all possible. Is it possible to overlap/merge DEM files the same way raster maps are?


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 Post subject: Re: Geo Data - Australia
PostPosted: 28 Aug 2016 16:10 
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Joined: 05 Jan 2011 16:45
Posts: 1463
The prefabricated big LIDAR files won't work with TransDEM. I have explained one of the reasons here:
http://forums.auran.com/trainz/showthre ... ost1521150


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 Post subject: Re: Geo Data - Australia
PostPosted: 28 Aug 2016 16:33 
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Joined: 27 Aug 2016 05:00
Posts: 33
Well, it works for small areas, so I guess its the issue with 32 vs 64 bit? The difference so far as I can see is file size.

Anyway, I currently plan to just do a series of lots of individual requests for the LiDAR DEM data around the route. Will be slow, but I guess its going to be a much better result than the DEM-S SRTM data.


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 Post subject: Re: Geo Data - Australia
PostPosted: 25 Mar 2018 16:35 
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Joined: 28 Mar 2011 03:35
Posts: 83
Bit of a bump, but having started looking at a Tasmanian route after a discussion on the N3V forum, the "Elvis" site linked above appears to be deads.

There is a TasMap site https://maps.thelist.tas.gov.au/listmap/app/list/map but it is not at all clear how that can generate DEM or LIDAR data and the topographic map appears to lose the railway line at 1:50,000 or less resolution.


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 Post subject: Re: Geo Data - Australia
PostPosted: 25 Mar 2018 17:33 
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Joined: 05 Jan 2011 16:45
Posts: 1463
Just had a brief look. There appears to be a 25m DEM free of charge.
http://listdata.thelist.tas.gov.au/opendata/
Look for "Tasmania 25 Metre Digital Elevation Model".
ASCII grid, UTM/WGS84 (equivalent to MGA/GDA94 for TransDEM purposes), southern hemisphere, zone 55

Map-wise, doesn't OSM get you there? Some of the LISTmap data may also be available via WMS but I haven't checked for the URLs.


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 Post subject: Re: Geo Data - Australia
PostPosted: 25 Mar 2018 21:05 
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Joined: 28 Mar 2011 03:35
Posts: 83
Ah thank you Roland, that will be much better. I also got a geotiff file from the Geoscience people which is purportedly at 5m resolution but I will look at both sets of data in the morning. I presume as regards the 25m resolution data, it's the asc file I need?


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