TransDEM Forum

KenRuof wrote:First thing is there a way to truncate the DEM as I only need

I get an hour glass 100% of the time for an hour or so and no file. I have an i7 with 6GB memory and was wondering if that is no enough. Each DEM is about 380,000KB in size. I can add dem's (3 total so far) but cannot save them as a unit.

Also I have been having random TransDEM crashes, sometime when doing georeferencing on TIFF files and sometimes when working with the large USGS data.

geophil wrote:

KenRuof wrote:First thing is there a way to truncate the DEM as I only need

Yes, there is. Drag a rectangular mask (default cursor tool, press and hold left mouse button) around the area you wish to preserve. Then select the scissors tool and click outside the mask. Check the parameters in the pop-up dialog, i.e. accept the defaults, and press OK. Save the cropped DEM.

Great, I will try that when I get home! It should help with some of the problem since I only need about 1/3 of the DEM data.

I get an hour glass 100% of the time for an hour or so and no file. I have an i7 with 6GB memory and was wondering if that is no enough. Each DEM is about 380,000KB in size. I can add dem's (3 total so far) but cannot save them as a unit.

TransDEM should be able to merge two 1 x 1 degree chunks in 1/3 arc sec on 64 bit Windows, but I don't think three will fit. I would have expected an error message, though. Could you tell me the coordinates of the 1 x1 degree DEMs you tried to merge (folder names) and in which order you tried to do it? The order could play a role if different longitude DEMs reside in different UTM zones and TransDEM has to convert the UTM zone.

I have been able to merge 3 1x1 1/3 arc data but I cannot save it. Last night I tried something, I loaded 2 DEM's the rastors I had, drew the route. I saved the route and exported to TS12 and it worked. So it is not that important to save the over all DEM as long as it covers the area I want and I can try merging in TS2010 since TS12 is broken for large routes if I need 2.

Also I have been having random TransDEM crashes, sometime when doing georeferencing on TIFF files and sometimes when working with the large USGS data.

Are you running 32 or 64 bit Windows? If 32 bit the memory limit is 2 GB for the TransDEM process unless you tune the operating system. Then the limit is 3 GB. Instructions in the TransDEM manual. On 64 bit the limit is 4 GB for the TransDEM process. Georeferencing large uncompressed images may lead to memory exhaustion. TransDEM tries a couple of things to save on memory usage and it will detect memory limits in several cases but not always. Loading many raster or large raster images may also exhaust memory. In all these cases I suggest to reduce route module size. TransDEM generated route modules can be merged in Surveyor later. The static mapping in TransDEM between UTM coordinates and Trainz baseboards should allow seamless merging.