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File size limit for map files?

Posted by Magnus 
File size limit for map files?
July 28, 2015 10:46AM
I'm having some issues with using a relatively large 1:25.000 scale map.
I've tried exporting it from my GIS-software in .jpg, .tiff, .bmp and .png, in resolutions from 50-300DPI. Depending on file type and resolution, file sizes range from ~25mb to ~800mb.

Sometimes, the map file will work, and suddenly, I'll get an error message that the map can not be imported.
Once this error has occured for the map file in question, that file will never work again - and the only solution is to either crop the map (which I'd like to avoid, as working with one map file of all courses is much easier than cropping correctly) or reducing the resolution, which is not an option.

Is there a workaround to this issue?
As I said; sometimes it works, but I just haven't been able to figure out why it suddenly stops at times.
Sometimes, I'm even able to get a file with a larger file size due to format (BMP) to work, while a smaller file (jpg or png for instance) which covers a larger area won't work.
Finn Arildsen
Re: File size limit for map files?
July 28, 2015 11:20AM
Hi Magnus,

Condes does not set a limit for the size of a bitmap file. It is the available amount of free memory on the PC that sets the limit. So if there is not enough free memory on the PC, Condes rejects opening the file.

A bitmap file is typically contains a compressed version of the bitmap image. When opening the bitmap file, Condes recreates the bitmap image in memory in order to be able to show the image on the screen.

The reason for not being able to open the file again, could have to do with memory becoming fragmented so that Condes cannot allocate enough memory. Does it make any difference if you restart your PC - this at least resets the allocated memory?

I have not tested Condes with bitmap files of several hundred MB, andI am not surprised imagine that this would create problems due to the huge amount of memory the uncompressed image would take.

Regards,
Finn
Thank you - it seems you might be right in that clearing memory might help!

What's strange though is, that I have 8gb available, at idle with just two browser-tabs and a few misc. programs, I still have 4.5GB free, if I open Condes with the large map, it will use approximately the filesize of the map (makes sense), but that should still leave 3.5+ GB available, but with anything less than approximately 4, I'm not able to change the map to another large map-file or open another Condes-instance with a similar map file, which seems strange to me, as there should be plenty of available memory.
A small update; even though Condes is able to load my event with the large map, the map is excluded when exporting a course.
I can even change the map file to a smaller and re-load the large map file when remembering to clear the memory, but still; when exporting, I just get the course and any graphic objects I've added, no background map!
Finn Arildsen
Re: File size limit for map files?
July 28, 2015 09:44PM
My response was not 100% accurate, come to think of it. There is also a limit to the amount of memory available to a program due to the size of the address space that a program can address. Condes is a 32 bit program, so can address 2^32 bytes = 4 GB.
Finn Arildsen
Re: File size limit for map files?
July 28, 2015 09:47PM
So when all the memory available to Condes is already used to load the bitmap, I would presume that there won't be any memory left for when the output image for printing is to be created.
Still - 4gb should be plenty, the program only uses ~7-800mb (approximately the file size for the map), and there is plenty available in the system, so there should be plenty left?
Finn Arildsen
Re: File size limit for map files?
July 28, 2015 11:07PM
As I mentioned, the map file is highly compressed and the contents will be expanded when read into memory. It is not unlikely that the amount of memory needed would be 3-4 times the size of the file.

I'm afraid that this is beyond what Condes was designed to handle.
But as I said; I can clearly see, that the program is not using any more resources/memory and that there is plenty available.
Today, as an experiment, I tried the same procedure on my work-computer, which has 16gb ram, and even with ~10-11gb available, it stalls when trying to add the map.

And as I said; it's been working previously and still does occationally, which is why it seems strange to me.
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