I have a table a postgis table of isolines that's defined like this:
CREATE TABLE myisolines ( gid serial NOT NULL, isotime timestamp without timezone, val numeric(10,4), geom geometry(LineString,4326) );
Visually this linestring objects look like this:
I know the spatial extent of my data, so I can add a Bbox, so the LineStrings can be sort of closed.
I want to create a table of isopolygons
myisolines table, with polygons, that won't overlap but create a continuous surface and have a column
val with the lowest
val of isolines, from which the polygon was formed. I understand it can be formed from self-closed isoline (island), or isoline closed with bbox, in that case the
val should be taken from that particular isoline. Visually it should look like this:
I thought that I can create topology somehow and then transform faces to polygons, but I don't understand how to do it properly. How can this be done?
Another option would be to recursively use a difference function between bbox and each created polygon, but I guess that's not the right way to do it, and definitely not fast at all.