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Messages - crunch

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First I need to make a correction, I actually use 0.5x0.5 arc degree areas with 10ft distance between the lines, as Florida is supposedly very flat, for the contour calculations.  With 1.0x0.5 I run out of memory already in the second quad (Bay Minette).  Funnily enough the the error is something like: "Unable to save ...." (Sorry, cannot remember the exact text at the moment).

I did a comparison of the generated contour files for quad "Dothan":

With 1.0x0.5 arc degrees one gmp file with 336415767 bytes is generated, with 0.5x0.5 arc degrees two files with 13503542 + 14945378 = 28448920 are generated, so for some reason less bytes (10x less!!) are generated for the same area by only reducing the contour grid size.

Yes, maybe more memory would solve the problem, but that the areas with only water in them lead to problems hints at a problem in Global Mapper.  I had two more problems with "ocean only" elevation data and removing those areas seems to solve the problems so far.  Also, about how much more memory are we talking? My machine has 2GB plus virtual memory, as it is running on XP there is not much room for more (3GB usually, or 4GB with tweaks).

Volker

@savage: Maybe reducing the contour grid size solves your problem.

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Map Making Support / Problem generating coutour files for FL topo map
« on: August 17, 2008, 03:17:35 PM »
I am following the tutorial to generate a FL topo map. I have a small problem with the data for the New Smyrna Beach quadrant (29.5 north, -81 west).  When generating the contour files for that quadrant Gobal Mapper chokes on the third ArcGrid file for that quadrant with a "Unknown error generating contours." error message.  I used the recommended values from the tutorial and a 1 arc degree for width and 0.5 arc degree for height.

That quadrant is a little strange, as only the first (west) data file holds land, the remaining three show only water.  I could reproduce the error using only the elevation data for that quadrant, and processing only the first two solves this problem.

I restarted the processing for all FL DEM files.  Lets hope there is no other problem, it took already a couple of hours to get to this problem and the progress bar only says 25%.

Is this a known problem, and does another workaround exist?

  Volker

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