[postgis-users] A question on ST_RemEdgeModFace usability

Andrea Peri aperi2007 at gmail.com
Thu Apr 12 14:08:10 PDT 2012

>I think your questions are related with a previous post today about
>synchronizing topogeometries.
>In fact, for editing topogeometries without using primitive commands I
>was thinking in:
>1.- Delete the topogeometry
>2.- Remove the primitives which depend just on the geometry deleted.
>3.- With totopogeom insert again the whole geometry
>I know this procedure is not optimized at all but maybe this way (with a
>new function which does this work)  one can avoid the complicated task
>about using primitive editing commands and to edit the relation table
>I have the feeling I not taking into account many things though.
>What do you think about this procedure Sandro?

Hi, I guess is not sufficient delete the single topogeometry. An edge could
be linked to one or two faces,
and also the same edge could be linked to many topogeometry.
Infact the topogeometry not necessary need to be mutually exclusive to
each-other ans instead are the topology edge and faces.

So I could have more than one topogeometry on a single edge.
And I should remove also every topogeometry that is linked to the edge I
would remove.

So I could have, for example:
on this sample:

    /          |       \  (universe Face)
    |          |       |
    |      F1  | F2    |
    |          |       |
    |          e1      e2
    |          |       |
    /                 \
    |                 |
    |        F3       |
    |                 |
    |                 |
    |                 |

A topogeometry T1 = F1 + F3
another topogeometry T2 = F2 + F3
and another again T3 = F2
and again a topogeometry T4 = F1

so if I plan to remove the edge "e1" I should save all four
topogeometry and re-apply them after.

Andrea Peri
. . . . . . . . .
qwerty àèìòù
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