Failure to Correctly Export Areas

Roger Edrinn
Roger Edrinn Global Mapper UserTrusted User
edited May 2009 in Vector Data
I'm working with a 7 x 4 deg extent, perhaps a dozen layers. I'm in the layer debug phase and only exporting 2 - 15x15-min extents as Polish MP files. I have an overlapping area that shows on one 15-min extent, yet not the other. Similar area types show on one and not on the other, overlapping or not.

But I have other areas of the same MP_TYPE with different feature names and they show on both extents. If I look at the master GM workfile and zoom in, all the areas are present and I can ID each.

I've opened the MP code in a text editor, the areas are indeed missing. Also tried GPSmapedit, again the area(s) are missing.

The area source layer is collection of shapefiles > GM workspace > GM Package file. I suspect it is somehow the package file which is the problem, admittedly a guess.

I'm doing the vector export with GM 9.03 3-16-2009.

Any ideas what's wrong or a test to try?

Comments

  • Roger Edrinn
    Roger Edrinn Global Mapper User Trusted User
    edited May 2009
    Another data point:

    I opened just the 4 x 7 deg area package file, exported the same two 15x15-min extents to .MP files and was able to replicate the export error.
  • Roger Edrinn
    Roger Edrinn Global Mapper User Trusted User
    edited May 2009
    Here's the zipped GM Package file, should you care to play:

    I'm exporting from N38.75 to N39 & W106 to W 106.5. The San Isabel NF shows always on the left, but only sometimes on the right extent. The Pike NF, same area type shows on the right.
  • global_mapper
    global_mapper Administrator
    edited May 2009
    Roger,

    I'll take a look and see if I can reproduce the problem.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • global_mapper
    global_mapper Administrator
    edited May 2009
    Roger,

    I took a look and found the problem. It was caused by the export clip boundary passing through duplicate islands/holes stacked on each other in the area being cropped. I was able to update the exporter to detect this situation and fix it automatically so everything should work now. I have placed a new build at http://www.globalmapper.com/global_mapper10.zip with the change for you to try. Simply download that file and extract the contents into your existing v10.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
  • Roger Edrinn
    Roger Edrinn Global Mapper User Trusted User
    edited May 2009
    When it took awhile, I suspected you quickly replicated the error. However, figuring out why was a bit tougher.

    Given these are holes inside an area and not over an area, I'm puzzled as to why they would prevent the proper export? Also puzzled why another complex If-Then to detect them versus deleting the duplicates?

    Also, how did GM create the duplicates in the first place?

    Just curiosity.
    Thanks
  • global_mapper
    global_mapper Administrator
    edited May 2009
    The algorithm for cropping a polygon with holes to a rectangle failed when duplicate islands were there as the edge couldn't be properly followed. All that is done to fix the problem is to detect the duplicates and delete them before running the polygon through the clipper.

    GM wouldn't have created the duplicates automatically, they were likely either in the source data, or the same hole was added to an area multiple times.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com

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