View GM_LayerInfo_t in the GM GUI

codemousecodemouse Global Mapper UserPosts: 186Trusted User
edited September 2013 in SDK
Mike,

I'm trying to use the GUI to help validate some math I'm doing via the SDK. Suppose I have a south on my mGlocalRect from the SDK that shows me a value of "20898.489320809844". Where can I see these values in the GUI? If I go to export elevation, I see on the Export Bounds tab, there seems to be values that are "close" filled in to the Global Projection boxes in the middle, but they are not exact (they seem a tad smaller?) - for example, South in the GUI box there says "20897.2389357141".

Is there any way to cross-validate in the GUI the values returned from GM_LayerInfo_t? I ask this because while doing my own gridding, I'm running into some precision rounding issues that I'm trying to alleviate - and I need to start with making sure my boundaries are at least consistent (I don't care about very precise values right now, just consistency).

Brian

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2013
    Brian,

    If you select a layer in the Control Center and press the Metadata button that will give you most of the same values that are in GM_LayerInfo_t.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited September 2013
    Mike,

    Yes - that's what I was looking for, thanks - HOWEVER

    That gives me an even different number for the same Coord (even less precision): Lower Right Y - 20898.776.

    Is there a better way to reconcile all of these precisions? Now I have the SDK telling me 20898.489320809844 and Metadata saying 20898.776 (those are in meters). I realize they are not off by THAT much, but when dealing with bounds in gridding I am trying to make sure I do not grid "out of bounds" and end up with 0 elevations. Thoughts?

    Brian
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2013
    Brian,

    The text metadata dialog will round the coordinates for display rather than showing a bunch of meaningless precision. The GM_LayerInfo_t of course has the full double-precision value. However there will be a difference for elevation in that the layer info would have the outer edge of the cells and the metadata reports the cell centers. For imagery layers they are the same.

    If you do it programmatically, just use the bounds right from the GM_LayerInfo_t.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • codemousecodemouse Global Mapper User Posts: 186Trusted User
    edited September 2013
    Mike,

    Thanks - I understand the metadata reporting the cell centers, makes perfect sense. Thought I wouldn't call the precision "meaningless" :). I vote to have full precision listed somewhere in the GUI and possibly even to have some identifier saying its from the cell center for elevation (I can't think of an ELEGANT way to show that, but it would be nice in future versions).

    Either way, I now know what the deal is - so this works for me, thank you!

    Brian
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