PenUp Mode/Display

giversongiverson Global Mapper UserPosts: 10Trusted User
edited August 2009 in Suggestion Box
We use duplicated points in our shapefiles to indicate to our display units whether or not a polygon line segment is supposed to be drawn or not. This provides a seamless border between polygons where there is supposed to be no border.

This suggestion is for a PenUp Mode and the display of these codes. Most GIS software applets go out of their way to remove duplicated points but the reality is, it is the only way to identify invisible borders without a separate data item. Ironically, the removing of these duplicated points by some applications (not Global Mapper but I won't name names) have caused much more severe issues than the relatively small data size increases from the points being left in.

An example of where you would want something like this is through the channel on Lake Michigan and Lake Huron.

The PenUp Mode would be a mode that could be set so vector extraction doesn't remove duplicated points.

For the PenUp display, I'm looking for an alternate border drawing specification so we can see where these things are. Currently, no GIS software on the market does this or anything similar to this.

A PenUp code is specified the following way:
0,0 -> Original Point
0,0 -> Indicates a PenUp Code
1,1 -> Creates an invisible line to 1,1; Resets the PenUp

Note that a PenUp flag can not be set on 2 consecutive points, though:

0,0 -> Original Point
0,0 -> Indicates a PenUp Code
0,0 -> Creates an invisible line to 0,0; Resets the PenUp
1,1 -> Creates a visible line to 1,1

On a side note, is there any way to do the vector extraction so it maintains the polygon part aggregation? I'm having multi-part polygons being broken up into 100's of separate records.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2009
    I think what could be added without too much trouble is a flag on the Vector Display tab to specify that duplicate points should be highlighted, then a small highlight, like a small circle around the duplicate vertex, could be drawn to highlight those.

    Regarding the multi-part polygons, the Global Mapper data model doesn't support having multiple separate parent polygons as part of one record, so there really isn't a way to maintain the multi-part polygons for export to a new file in Global Mapper.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • giversongiverson Global Mapper User Posts: 10Trusted User
    edited August 2009
    The highlighted point buys me very little...mainly, because the directional arrows only display on line features and even that isn't a foolproof method of associating the line to the penup.

    It doesn't sound like you're too keen on incorporating the penup into your software and that the duplicate point is about as far as you want to lean. If you are, a highlight for the line segment would work really well.

    I guess the best way to handle this is to write my own rendering software or a utility that breaks my polygons into 2 line features and throws them into another shapefile.

    Also, that exploding all my polygons thing is one of the main things stopping me from using global mapper as an editing tool (though it's my preferred visualization tool with a few flaws). I have to assign a unique ID to each polygon and recombine all my polygons afterwords using a custom Python script. I need a utility that doesn't significantly alter my geometry without me telling it to.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2009
    Good news, I was able to implement a new pen up/pen down mode using duplicate vertices without too much trouble. There is an option at the bottom of the Vector Display tab of the Configuration dialog that enables this behavior. I have placed a new build at http://www.globalmapper.com/global_mapper11.zip with the change for you to try. Simply download that file and extract the contents into your existing v11.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
  • giversongiverson Global Mapper User Posts: 10Trusted User
    edited August 2009
    That works perfectly.

    Thanks
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