[postgis-users] A question on ST_RemEdgeModFace usability

[Jose Carlos Martinez Llario]

Just to add that for a normal user to think in primitives is going to be 
kind of difficult. To try to delete an edge or change a topogeometry can 
be very tricky.

My opinion is that a user should work with topogeometries as if they 
were normal geometries. PostGIS in a transparent way should deal with 
the primitives. I know Im asking too much. Not for now. I already happy 
a lot with persistent topology as it is right now.


On 12/04/2012 23:15, Jose Carlos Martinez Llario wrote:
> On 12/04/2012 23:08, Andrea Peri wrote:
>> >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
>> >manually.
>> >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.
> Thats why I said to remove just the primitives which depend on the 
> geometry deleted (and not from any other one). This way one can clean 
> the primitives which are not shared by any other geometry. Its like 
> the garbage collector Sandro said before.
> After that one can insert again the whole modified geometry.
> Dont know if I could explain myself.
>
>>
>> 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
>> -----------------
>>
>>
>>
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>
>
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20120412/4110aa79/attachment.html>