Friday, 15 June 2018

Problem with MCC-LiDAR (insufficient memory)



I am running mcc-lidar on a win7 64bits with 16gb of ram. Nevertheless when I try to process a las file with 1, 800 000 points using -s 0.5 and -t 0.3 the program tells me:


Error: insufficient memory; if applicable use a larger post spacing.


I am able to process the data using -s 1.5 -t 0.3, so I figure the problem is not with the number of points.


The program is installed at c:\program files (x86), which I understand is for 32 bits programs. Is there some specific instructions to install it as a 64 bit application in order to use my 16 gb of RAM?



Answer



Currently there is not a 64-bit compile although the source code is available so, you can compile it yourself using a 64-bit compiler.


I find your issue odd. 1.8 million points is not a very large problem and <1m post-spacing is common. Usually vendors tile lidar into < 20 million points and MCC has never demonstrated memory issues on 15-20m points on 32-bit systems with as small as a 0.5 post pacing (s=0.25). Perhaps you have sparse post spacing over a large area and there is insufficient RAM to create a 0.5m spline surface.


Is your data, in fact, 1m post spacing? The starting scale parameter should be 1/2 the post spacing. This defines the resolution of the spline surface in the first model iteration.


One immediate solution would be to create smaller tiles. Another option is to thin the data by querying for last returns and running the model on the resulting data. If you do this you will need to play with the parameters.


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