Problem with intersection

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AlejandroMaximus
Posts: 1
Joined: Mon Aug 24, 2020 3:16 pm

Problem with intersection

Postby AlejandroMaximus » Mon Aug 24, 2020 3:29 pm

I am having some problems with the intersection function. I am programming a TCl script that uses the intersect function. Unfortunately the intersect function is not very reliable. Sometimes after intersecting the two volumes involved are simply gone. This case is however easy to intercept by checking the number of volumes present in the layers involved, slightly changing one of the volumes and repeating the intersection until it works. Just recently, however, another error occured. After intersecting an info window pops up saying: "Volume not closed, surfaces: xxx, xxx". I also want to intercept this error in my tcl script and somehow need a return value from the intersect function I can use.

Thanks for your help,
User avatar
escolano
Posts: 1638
Joined: Thu Sep 18, 2014 3:31 pm

Re: Problem with intersection

Postby escolano » Tue Sep 01, 2020 8:41 pm

You are right,
the boolean operations, and the intersection are not robust operations in GiD.
Must solve problems of intersection curve-curve, curve-surface, surface-surface, and alle these operations involve solve non-linear systems,
with multiple or zero solutions, and become not very reliable. It depends a lot of tolerances.

It is difficult to handle possible errors, only in particular cases you can check the ids of new entities, ids are always increasing.
Can know before for example the maximum pointid with
set max_point_id [GiD_Info geometry MaxNumPoints]
and check the new ids after an operation
e.g. with
GiD_Geometry list point

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