How to detect holes between contiguous polygons with MapInfo Pro

[Martín Ancarola]

Hello, I´m new using MI, I need to Know if is there any way to detect empty spaces between two polygons that have to be contiguouos by sharing a common boundary. I Understand that the Gap detection option in the Check regions object tool only detect gaps inside closed polygons but i need to detect when two polgons supposed to be closed are not, leaving a hole between them.....well... I need to detect this hole....Is there any standar tool for it with MapInfo?.

Regards

Martin Ancarola

[Tony Pilkington]

Similar to David’s technique, open the poly table and make the cosmetic layer editable.

Select all from poly table and copy and paste into the cosmetic layer;

Select all from the cosmetic layer; use objects –> enclose

Use Objects –> Set Target

Using the Query sql of select * from poly table, use objects –> erase.

 

This will leave a set of small polygons in the cosmetic layer which are the holes between the polygon edges.

It will not show fissures at the edges. David’s method will show these as spikes.

You can use map –> save cosmetic objects to save the holes as a table

 

It is now your decision as to how to repair these holes. It rather depends on how faithful the new table has to be to any base mapping you may be using.

If you do not have a large number, do it manually; if you are just moving the odd point, set snap on, use the point edit button and move the point until the snap cross is shown against a point on the neighbouring polygon.

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[Tony Pilkington]

I’m attaching a zip file containing a small mbx and some test files that may help you. The mbx removes gaps and overlaps between polygons that are meant to be contiguous. It attaches holes to polygons; holes in the middle of polygons are assumed deliberate and left. Overlaps between polygons are removed. An example table (raw_data_1),  is in the attached zip file which after adjustment becomes raw_data_1_adjusted. The holes and overlaps are shown in raw_data_1_interstices. A couple of screen shots are in the zip file too.

 

To run the mbx, close down all other tables and load the mbx. Work from left to right of the buttons. Save your results. The program does adjust the objects in your table, so work with a copy of the polygon table. The resulting polygons will need to be checked against base mapping or imagery.

 

Good luck

 

Tony

 

 

 

From: Martín Ancarola

Sent: Wednesday, March 06, 2013 2:46 PM

To: mapi...@googlegroups.com

Subject: [MI-L] How to detect holes between contiguous polygons with MapInfo Pro

 

Hello, I´m new using MI, I need to Know if is there any way to detect empty spaces between two polygons that have to be contiguouos by sharing a common boundary. I Understand that the Gap detection option in the Check regions object tool only detect gaps inside closed polygons but i need to detect when two polgons supposed to be closed are not, leaving a hole between them.....well... I need to detect this hole....Is there any standar tool for it with MapInfo?.

Regards

Martin Ancarola

[Martín Ancarola]

Thank you very much for hel Tony. I will try this technique.

Regards

Martin