split polygons by lines

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11-11-2013 08:19 AM
katherinehannaford
New Contributor III
Hello all,
I want to split a polygon (or many polygons in one shapefile) by a line feature using the Advanced Editing Toolbar Split tool .  It's exactly the type of situation shown in the "split polygon by overlapping features" entry in Help (which uses the Split tool).

[ATTACH=CONFIG]29017[/ATTACH]    

Here's my scenario

[ATTACH=CONFIG]29016[/ATTACH]
What I really want to do is split the green polygon by the river lines and end up with 3 new polygons in a new shapefile.  But I keep getting an error msg "No polygons were split.  Ensure the selected features form continuous rings and overlap the polygons."  the help only says to select the line(s) but I've also tried selecting both the lines and the polygon.  The straight diagonal line is one I made as a test to control for possible gaps in the river lines, but that didn't work either.

I have an Advanced license for 10.1.  Any help on what I'm missing here?
Thanks.
kathi
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katherinehannaford
New Contributor III
OK, I do seemed to have worked out the problem.  The help was not at all explicit about identifying the feature classes ("to be split", versus the polygon "target", versus "use to split"), what needed to be editable, or where the feature classes needed to be located (in the same workspace or not), what needed to be selected.  I still don't know the answers to all those questions, but I did get the split tool to work properly under the following conditions:  with everything in the same workspace, choosing that workspace as editable rather than a specific shapefile within it, and selecting the feature (line/s) to split with but not the polygon to be split (the "target").  And it did work just fine with my multi-feature river line, so I'm happy (although unhappy with the help entry). 
Thanks for your suggestions and encouragement.  I appreciate it.

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by Anonymous User
Not applicable
Original User: rfairhur24

Hello all,
I want to split a polygon (or many polygons in one shapefile) by a line feature using the Advanced Editing Toolbar Split tool .  It's exactly the type of situation shown in the "split polygon by overlapping features" entry in Help (which uses the Split tool).

[ATTACH=CONFIG]29017[/ATTACH]    

Here's my scenario

[ATTACH=CONFIG]29016[/ATTACH]
What I really want to do is split the green polygon by the river lines and end up with 3 new polygons in a new shapefile.  But I keep getting an error msg "No polygons were split.  Ensure the selected features form continuous rings and overlap the polygons."  the help only says to select the line(s) but I've also tried selecting both the lines and the polygon.  The straight diagonal line is one I made as a test to control for possible gaps in the river lines, but that didn't work either.

I have an Advanced license for 10.1.  Any help on what I'm missing here?
Thanks.
kathi


The example you showed from the help has a single line feature that is crossing the entire polygon.  That is not true of the rivers you want to use to split the polygons.  Right now there are three separate lines, none of which fully cross the boundaries on each side of the polygon.  The three lines all end at the junction where the three lines meet in the interior of the polygon.

To use these river lines you would have to copy the three lines at least one more time and merge all opposing pairs at the junction of those lines to forms a single line that cuts a full 1/3 portion of the polygon.  Each continuous river line must fully cross the whole of the polygon from polygon boundary to polygon boundary.  This would mean a line merging the two upper most lines to cut the top 1/3, two eastern most lines merged into one to cut out the eastern 1/3, and two western and southern most lines merged into one to cut the southwestern 1/3.  The lines would overlap each other in all cases, so you should do this in a separate duplicate feature class copy of the original river lines.
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katherinehannaford
New Contributor III
The example you showed from the help has a single line feature that is crossing the entire polygon.  That is not true of the rivers you want to use to split the polygons.  Right now there are three separate lines, none of which fully cross the boundaries on each side of the polygon.  The three lines all end at the junction where the three lines meet in the interior of the polygon.

To use these river lines you would have to copy the three lines at least one more time and merge all opposing pairs at the junction of those lines to forms a single line that cuts a full 1/3 portion of the polygon.  Each continuous river line must fully cross the whole of the polygon from polygon boundary to polygon boundary.  This would mean a line merging the two upper most lines to cut the top 1/3, two eastern most lines merged into one to cut out the eastern 1/3, and two western and southern most lines merged into one to cut the southwestern 1/3.  The lines would overlap each other in all cases, so you should do this in a separate duplicate feature class copy of the original river lines.


Thanks for your response.  I considered that possibility, but even using a single feature across the polygon (see the diagonal line in "my scenario" I got the same error message.  Any other ideas?
kathi
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by Anonymous User
Not applicable
Original User: rfairhur24

Thanks for your response.  I considered that possibility, but even using a single feature across the polygon (see the diagonal line in "my scenario" I got the same error message.  Any other ideas?
kathi


I followed the steps listed in the help you mentioned and they worked as expected for me.  I selected a continuous, single-part line that fully crossed a polygon and pressed the "Split Polygon" tool on the Advanced Editing toolbar (there is no plain "Split" tool on that toolbar).  I confirmed the polygon layer I wanted to split and the tolerance in the dialog that came up and the polygon split along the line with no issue.

I only got the message you reported when the line did not fully cross the polygon or when I used a multi-part line feature that had a break in the line within the polygon.

According to the name of the test line layer, the test line is dissolved.  A dissolved line may be a single feature, but not necessarily a SINGLE-PART feature unless you unchecked the multi-part option for the tool.  With the dissolve tool it could possibly be a multi-part line that contains a very small break in the line somewhere within the polygon.  If there is any break in that line, no matter how small, it will result in a failure of the tool.  You could use the Multi-Part to Single Part tool to verify whether or not your test was using a genuinely single-part continuous line.

If you actually drew a single part two-point line for your test then I am not sure what is going on.  It works as expected for me.  You would need to walk through each step you are doing exactly and start with a test where you use a two-point line that you have drawn and know for sure fully crosses your polygon.
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katherinehannaford
New Contributor III
The diagonal line feature is definitely single part, created directly from 2 clicks.  Are you using 10.2?  I'm suspicious that this might be the problem (I'm using 10.1), even though the help entry doesn't specify.  But I'll try the process again just to see if I get the same error message today.
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by Anonymous User
Not applicable
Original User: rfairhur24

The diagonal line feature is definitely single part, created directly from 2 clicks.  Are you using 10.2?  I'm suspicious that this might be the problem (I'm using 10.1), even though the help entry doesn't specify.  But I'll try the process again just to see if I get the same error message today.


I am using 10.1, SP1 Advanced license just like you so your suspicions are not warranted.  You may want to run Check or Repair Geometry tools on your data to be sure there is nothing corrupted in your feature classes.  Then you just need to walk through it step by step in detail to be sure there is no deviation from the instructions.  I would try it with a new polygon layer and a new line feature class and make both features very simple.  If it fails even then, from my perspective you have a problem that is seriously wrong and that should not be occurring.

At this point you may want to call it in as a support request.  ESRI will require you to do everything step by step as they instruct you or watch before they will accept that you have a problem that is not caused by user error.  They also will have to reproduce it before they write a ticket for it.  I cannot reproduce it, and it would be better for you to share your data with ESRI to see if they can reproduce the problem, since they are the only people who could correct it if it isn't due to user failure.  They will also do a much better job of going over all the details about your system that might be involved in your problem than I could.
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katherinehannaford
New Contributor III
OK, I do seemed to have worked out the problem.  The help was not at all explicit about identifying the feature classes ("to be split", versus the polygon "target", versus "use to split"), what needed to be editable, or where the feature classes needed to be located (in the same workspace or not), what needed to be selected.  I still don't know the answers to all those questions, but I did get the split tool to work properly under the following conditions:  with everything in the same workspace, choosing that workspace as editable rather than a specific shapefile within it, and selecting the feature (line/s) to split with but not the polygon to be split (the "target").  And it did work just fine with my multi-feature river line, so I'm happy (although unhappy with the help entry). 
Thanks for your suggestions and encouragement.  I appreciate it.

View solution in original post

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by Anonymous User
Not applicable
Original User: rfairhur24

OK, I do seemed to have worked out the problem.  The help was not at all explicit about identifying the feature classes ("to be split", versus the polygon "target", versus "use to split"), what needed to be editable, or where the feature classes needed to be located (in the same workspace or not), what needed to be selected.  I still don't know the answers to all those questions, but I did get the split tool to work properly under the following conditions:  with everything in the same workspace, choosing that workspace as editable rather than a specific shapefile within it, and selecting the feature (line/s) to split with but not the polygon to be split (the "target").  And it did work just fine with my multi-feature river line, so I'm happy (although unhappy with the help entry). 
Thanks for your suggestions and encouragement.  I appreciate it.


Glad you got it to work.  I am not sure which conditions are required and which are optional either, since my test followed all of the conditions of your successful test. Whatever works is the rule with ArcMap.
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TOMKONG
Occasional Contributor II
Hello all,
I want to split a polygon (or many polygons in one shapefile) by a line feature using the Advanced Editing Toolbar Split tool .  It's exactly the type of situation shown in the "split polygon by overlapping features" entry in Help (which uses the Split tool).
...
I have an Advanced license for 10.1.  Any help on what I'm missing here?
Thanks.
kathi


I had this problem also. I guess the issue is realted to mutipart polygons - when I cut them, some are ok and some cann't be cut.
To repair these polygons geometry may be helpful.
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by Anonymous User
Not applicable
Original User: dmhoneycutt

For future reference, here's a blog post about splitting polygons with lines.  It uses geoprocessing tools... no interactive editing stuff:
More adventures in overlay: splitting polygons with cartographic spaghetti
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