Splitting an Area

Roger EdrinnRoger Edrinn Global Mapper UserPosts: 721Trusted User
edited April 2010 in Technical Support
Mike,

A week or two ago we exchanged emails regarding splitting a shape-file area into two pieces and the unexpected consequences. Still a bit confused.

After splitting the area, GM9 automatically creates a new layer in the Overlay CC called: User Created Features.

Then I was told to export these as shape files and use Load Data to re-import the shape files. Worked sort of but again unexpected results.

Some specific questions:
- Can I import the shape-files into a specific layer? I got another new layer.
- Will I get another new User Created Features layer each time I make a split? Or will they all go into the same User Created Features layer?
- I expect to have dozens, if not 100s of these split areas and I'm trying to minimize the sheer number of layers. Is their a solution?

Thanks

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2007
    Whenever you load a file it comes in as its own layer. There is not any way to merge layers once they are loaded. To do that, you would need to export all of your data to a single new file, then unload the existing data and load that new file.

    All newly created features are added to a single User Created Features layer, so you don't have to worry about a lot of those being created.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited November 2007
    Thanks Mike,

    Both of those answers help a lot. :)

    I now have a way to re-integrate the data into their original sub-basins or manage in one extra layer all of my split areas.
    Whenever you load a file it comes in as its own layer. There is not any way to merge layers once they are loaded. To do that, you would need to export all of your data to a single new file, then unload the existing data and load that new file.

    All newly created features are added to a single User Created Features layer, so you don't have to worry about a lot of those being created.
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited December 2007
    Lately I've repeatedly run into a problem where I'm trying to split one area into two and GM offers to join the areas instead of split an area.

    Details:
    I'll start with a river fork, select the area with the edit tool, turn on verticies, select a vertice on one bank, then a second vertice. On the status line it shows 3 objects selected. Apparently, GM is self selecting a third vertice. This most often happens when their is an island in the river and somehow GM wants to select that island as a third object. In any case, when I right click to split the area, that option is not available and is replaced by a join option. The island is NOT between the two selected vertices.

    What is happening and how do I work around the problem?

    Thanks
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited December 2007
    Apparently this problem is in some way caused by having the check box "render deleted features" checked. Turning that off has things working as expected.

    You probably know why, I don't.

    Thanks
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited December 2007
    It sounds like you've probably got a deleted area feature underneath the area that you are trying to split and with the Render Deleted Feature option being checked that feature is being selected as well as the other one. The option to split a selected area had only been available when exactly one feature was selected. I have now made this available when multiple features are selected so long as at least one feature is an area feature with 2 or more vertices selected. 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
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited December 2007
    That makes sense now. I remember you saying that you don't actually remove the original area, rather it goes into the deleted bucket. When I checked "render deleted" I now have two. I was only seeing the artificial line which I needed for the river name. The undeleted river was there too.

    Thanks
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited February 2010
    Splitting an Area Part 2.

    So splitting an area by selecting two verticies is old hat. Now I want to get more sophisticated.

    Can I use an irregular line, consisting of many verticies, and use it to split an area?

    The most obvious answer seems to be to first split the area using two verticies, then delete that line and substitute my irregular line. However couldn't figure out how to make the substitution.

    Any suggestions?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2010
    You would need to upgrade to v11 to do this, but with the latest releases you can split an area against another area. So you could draw an area feature that uses your detailed split line through the intersection with the other area, then just goes around the outer boundary of the area to split. There is not any way to do this prior to v11 though.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • kaichand989kaichand989 Global Mapper User Posts: 4
    edited February 2010
    Hello,
    I am having more then 500 satellite image. i want to georeference images with DGPS points.
    I want to know is there any way to georeference satellite images in batch or batch geoprocessing of raster dataset .Is it possible using any software.
    I will be thankfull to you if you could help me to solve this problem
  • Roger EdrinnRoger Edrinn Global Mapper User Posts: 721Trusted User
    edited February 2010
    You would need to upgrade to v11 to do this, but with the latest releases you can split an area against another area. So you could draw an area feature that uses your detailed split line through the intersection with the other area, then just goes around the outer boundary of the area to split.
    If I understand this tool (Create new area feature(Trace Mode)), I would use my line/area as a guide. But the tool would actually follow my shaky hand and not snap to my guide?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2010
    You can use the File->Rectify Imagery menu command to batch rectify multiple images at once. You could still have to select your control points for each image, but you can do that for a series of images, then have them all export for you once you are complete.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited February 2010
    You could use the new trace tool to draw your boundary, but if you already have the desired cut line I would first draw another line starting at the end of your cut line, around the outside of the area, then to the other end of your cut line, then select those two lines and choose to create an area from the selected line, then use that new area as your cut area.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • GriffonGriffon Global Mapper User Posts: 19Trusted User
    edited April 2010
    Along the same topic line, I'm interested in clipping a polygon by another polygon (or more preferably just a multi-point line) in a way not afforded by the "Add island" method. For instance, in the attached example, I'd like to replace entire intersection from red X to red X with the corresponding edge from the cross-hatched polygon, including the area that expands the original grey polygon, not just reduces it. See finished clip. I can only do this by deleting those interior vertices in the grey polygon prior to the "adding island" command.

    The way I can do it with a line is to cut the line by the area, deleting the segments outside the area, then (1) convert the area to be changed to a line, (2) split the area->line at points where the clipping line meet it, (3) delete the segment of the area->line to be replaced, and (4) select the lines to be knit together into an area. But this is complicated work and even more complicated if their are surrounding lines and polygons that may be selected.

    Any other approaches?
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2010
    I think what may be easier than converting to lines and splitting and joining those would be to first draw another area that covers the hole area between the gray and cross-hatched area (it's ok if it goes into the cross-hatched area a bit), then combine that new area with the original gray area, then perform the 'Add Island' operation to remove the cross-hatched area. That should get you what you are after with a lot less complicated series of steps.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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