[postgis-users] A question on ST_RemEdgeModFace usability

[Jose Carlos Martinez Llario]

On 12/04/2012 23:31, Andrea Peri wrote:
> >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.
>
> Sorry, but I'm not sure to understand
> So I try to do an example.
> Suppose to have this topology and every topogeometry is coincident 
> with a single face
>
>     +----e1-------+----e2-------+----e3-------+
>     |             |             |             |
>     |             |             |             |
>     |    F1       |    F2       |     F3      |
>     e13          e14           e15           e16
>     |             |             |             |
>     |             |             |             |
>     +-----e4------+----e5-------+-----e6------+
>     |             |             |             |
>     |             |             |             |
>     |     F4      |     F5      |     F6      |
>    e17           e18           e19           e20
>     |             |             |             |
>     |             |             |             |
>     +-----e7------+-----e8------+-----e9------+
>     |             |             |             |
>     |             |             |             |
>     |     F9      |     F8      |     F7      |
>    e21           e22           e23           e24
>     |             |             |             |
>     |             |             |             |
>     +-----e10-----+-----e11-----+-----e12-----+
>
> topogeometry T1 = face F1
> T2 = F2
> and so on..
>
> If I suppose to whan remove the edge e19.
> That edge I plan to remove is boundary between the F5 and F6 and so 
> the edge e19 is boundary on
> Topogeometry T5 and topogeometry T6.
>
> You suppose to remove temporary the topogeometry T5 and T6 right ?
> After this use the ST_RemEdgeModFace to remove the edge "e19" and 
> after this reapply the two topogeometry
> T5 and T6 using the totopogeo ?
> I fear that the totopogeom will re.create the edge e19 calling it "e25" :(
If some edge change the id this is no problem and then you can insert a 
T5 or T6 topogeometries with totopogeom that are different from the 
original ones and totopogeom will recreate the primitives. Then the user 
does not have to know about primitive commands as: ST_RemEdgeModFAce, etc.

Dont take my opinion if a so serious way because Im just starting with 
persistent topology though.


>
>
> -- 
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
>
>
> _______________________________________________
> 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/fdee1922/attachment.html>