Possible BUG- GM 20 slow on large vector files

geomanniegeomannie Global Mapper UserPosts: 204Trusted User
I have just installed GM20 and was looking forward to the "Performance and processing improvements, especially when working with large vector files".

I use OSM XML data and country datasets can be large. For example the Scotland data https://download.geofabrik.de/europe/great-britain/scotland-latest.osm.bz2 from https://download.geofabrik.de/europe/great-britain/scotland.html decompresses to about 2.8GB. In GM 19 opening is slow at about 9-10minutes but once opened I can zoom and pan relatively freely. In GM 20 the file takes 20-22 minutes to open and once open if I try to zoom or pan, GM 20 freezes, or at least responds so slowly as to be unusable.

Despite the headline improvement in vector rendering, GM 20 is practically useless for these large vector files. Please can you investigate and fix?



Best Answer


  • samknightsamknight BMG Staff Posts: 88
    Thanks geomannie, we've got the sample and the developers are having a look.  I can replicate the behavior you describe.
  • bmg_mikebmg_mike Global Mapper Guru Posts: 185Trusted User
    It looks like the slow-down was caused by a change to our OSM import late in the v19.1.x cycle. At user request we started saving all of the attributes with the <node>'s in the file, like timestamp, user-id, etc., which blew up the read time and memory usage.

    I'm working on a fix to much more efficiently store those and make the drawing as fast as it should be. Once done I expect the OSM import will be faster than it was before and save more of the data.


    Global Mapper Guru
  • geomanniegeomannie Global Mapper User Posts: 204Trusted User
    Brilliant! Thanks a lot. This has knocked 2-3 minutes off the opening time of my example OSM XML file. Panning and zooming is now faster too.

    Cheers and thanks again for your very fast response.

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