Global Mapper v25.0

Reversing bound gridding calculations

giverson
giverson Global Mapper UserTrusted User
edited July 2008 in Suggestion Box
I use the global projection to specify the bounds of my export and and a 4 quadrant gridding system to measure the grid distance from the (0, 0) coordinate origin.

However, to use this on coordinates west or north from the origin (because of the top left origin of the raster), I must specify an even multiple of my grid size for the north and west corner and a substantial reverse buffer from my origin to make sure that I get grids that are located at a factor of the grid size from the origin and not get an extra grid that goes 1 past the origin (because of a rounding error). The math on this gets really nasty because of a conflict I have with the available datums and the datum I am forced to use.

Could you implement a method where, like the reversing numbering system, it also reverses the method that it calculates which side to overflow on.

For example, if I specify a 6k north, a -6k west bound, a 0 east and south bound, and a 12k by 12k grid, I want the option to have it generate the grid from 12k north, -12k west to 0 south and east instead of the -6k to 6k.

An oversimplified example, I know, but it really has it's merit when you're talking about having 100's of grids on each side of the (0, 0) point using a quadrant system.

Comments

  • giverson
    giverson Global Mapper User Trusted User
    edited July 2008
    Note: I'm unable to test whether the newest version handles this. There is still a reverse button but I assume it does the same thing as it does in 7.2 (a negative step). And I haven't found any mention, with a quick search, in the release notes for a change to it's functionality.
  • global_mapper
    global_mapper Administrator
    edited July 2008
    Would it work for you if I allowed you to enter a negative 'Grid Width' and or 'Grid Height' value, and in those cases the step would go from the right and/or bottom rather than the top left?

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • giverson
    giverson Global Mapper User Trusted User
    edited July 2008
    yes, that would work...
  • global_mapper
    global_mapper Administrator
    edited July 2008
    I have completed adding support for specifying a negative grid width and or height value when exporting. When a negative value is specified the grid cells will be snapped to the right and/or bottom of the export bounds rather than the left and/or top as is normal. I have placed a new build at http://www.globalmapper.com/global_mapper9.zip with the change for you to try. Simply download that file and extract the contents into your existing v9.xx installation folder to give it a try.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com