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PostPosted: 27 Aug 2016 07:54 
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I have a fairly large geotiff from google earth compiled with universal map downloader of a marshalling yard with detail level 21. Unfortunately it seems its too big for TransDEM to handle (1.6GB). Any suggestions on how I can split it up into smaller 'tiles' and have it retain the georeferencing information in it? I have a smaller version at detail level 19 or 20 (I forget which) that is only 450 MB, but that is still too large for TransDEM to handle - although it does get displayed in TransDEM (the larger one just shows a black rectangle).

Id prefer to use Google Earth tiles directly, but it seems its not a provider through the map tiles settings. That aside, splitting the image I already have seems like the best solution.


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PostPosted: 27 Aug 2016 09:03 
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G'day Blu3wolf,

I think the easiest option you have is to ascertain a point about half way along the yard and to individually load in the map tiles up to that point. Save these as an *.lgb file, then load in the rest (after deleting the first lot) and save these as a separate *.lgb file. You will need to work with these two 'parts' (providing each with its own DEM and route polyline) as separate entities until the route gets into Trainz. If you still issues, you will need to divide the route into further portiions...

Jerker {:)}


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PostPosted: 27 Aug 2016 10:16 
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Jerker wrote:
G'day Blu3wolf,

I think the easiest option you have is to ascertain a point about half way along the yard and to individually load in the map tiles up to that point. Save these as an *.lgb file, then load in the rest (after deleting the first lot) and save these as a separate *.lgb file. You will need to work with these two 'parts' (providing each with its own DEM and route polyline) as separate entities until the route gets into Trainz. If you still issues, you will need to divide the route into further portiions...

Jerker {:)}


Cheers! See the issue with this is that it isnt sets of tiles... its one single raster image of 1.6GB. I cant load it at all in TransDEM, even in parts. Photoshop will open it (slowly) but Im not sure, if I crop it with PS, whether the georeferencing will remain.


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PostPosted: 27 Aug 2016 16:09 
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Joined: 30 Jan 2011 13:03
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G'day Blu3wolf,

...the fact that it was a single 1.6 Gbyte file didn't come across in your initial post, so as you surmise, any cropping you make to it is guaranteed to mess with the georeferencing. The only EASY solution that I now see that you have is to undertake another attempt at getting the raster image, this time in smaller chunks in accordance with the instructions provided by our good friend 'HiBaller' in his tutorial, here (or you could use the nearly identical instructions provided by our 'mentor' "The Good Doctor" in the excellent Help files that accompany TransDEM, to do precisely the same thing)...

Jerker {:)}


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PostPosted: 27 Aug 2016 16:13 
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Cheers Jerker,

This is what I have been doing, using small chunks at a time. Slow, but better than nothing. Leaving me now to worry about gauge issues (not really a TransDEM issue there) and the DEM issue (other thread). Thanks for the advice!


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PostPosted: 28 Aug 2016 16:20 
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Joined: 05 Jan 2011 16:45
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Blu3wolf wrote:
Id prefer to use Google Earth tiles directly, but it seems its not a provider through the map tiles settings.

Have you tried to adjust the settings? See this older post and change to something like "kh/v=230".
viewtopic.php?p=1986#p1986

It seems, however, that this server no longer supports the lower zoom levels.


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PostPosted: 31 Aug 2016 05:38 
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Is there any chance a future version of the 64 bit software will support large images? I note that it handles having several images making a composite just fine, its only if its a single large image that it complains about.


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PostPosted: 31 Aug 2016 20:42 
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Joined: 05 Jan 2011 16:45
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Problem is that some of the image processing needs 64bit arithmetic, even in the 32bit variant. That naturally limits image size. Currently, TransDEM already makes use of a few tricks to keep memory usage down for images, e.g. it keeps images compressed until a clipping is actually drawn or processed. Even originally uncompressed images could see compression when worked upon. That means the whole image handling has been optimised for relatively small clippings, i.e. 32 Mega Pixel, but allowing many of them.

Any reasonable solution for larger individual clippings would have to subdivide an image into stripes or tiles for processing it. Such an approach exists, with striping, for georeferencing via Irregular Triangle Network (TIN). It's a niche function, and was quite a demanding task to implement, not an encouraging experience to apply it elsewhere.


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