Comments below
> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Bob Pawley > Sent: Monday, June 02, 2008 9:30 AM > To: PostGIS Users Discussion > Subject: [postgis-users] Creating a Flow Diagram > > > Hi Stanley > > I'm still in the primary learning stage with Postgis. > > I would appreciate you critiquing my thoughts. > > With the two tables - entity and entity_relationship - the idea is to > establish a parent geometry (perhaps a point known to be > within established > boundries) and establish the position of child entities ( in > my case, > process graphics) in relationship to the parent. That is correct. The entitity table would contain 2d/3d Polygons of your diagram entities. Points in this table would not work due to st_centroid in the would-be trigger function. A slight modification would fix this. > > Furthermore, you seem to indicate that any entity can be both > a parent > and/or a child to another entity. > Yes, this allows for one to many relations of parent to child (1-->2 && 1-->3) and for network diagrams > You also indicate that the placement of the child entity can > be established > in relation to the relative geometric sizes of the entities. > Yes, examples: For a parent entity (1) with a child (2) placed to the right of the parent, you would have entity_relation (1,2,1,0,0) For a parent entity (1) with a child (2) placed to the top of the parent, you would have entity_relation (1,2,0,1,0) For a parent entity (1) with a child (2) placed to the left of the parent, you would have entity_relation (1,2,-1,0,0) *If anyone actually produces a 3d diagram using the ratio_z, this would be a first in my book and would be very interesting to see. > Have I been somewhat correct so far? > > Bob > > _______________________________________________ > postgis-users mailing list [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
