Hi,
I want to create an fog of war. I use a start-polygon and in this should
be the area screened transparent where the user has build some buildings.
Here is the SQL-script that works if the user has a building of every
building-type but if he only has an "haupthaus" no geom will be
created???!!!
But at the beginning the user only has the building: haupthaus-->and for
this starting situation a fog of war has to be created.
UPDATE fog_of_war2
SET the_geom = (SELECT ST_BuildArea(
St_Collect(grenze_by.the_geom,
ST_Union( ST_Union(
ST_Union(ST_Union(ST_Expand(holzfaeller.the_geom,
2000)),ST_Union(ST_Expand(steinbruch.the_geom,2000))),
ST_Union(ST_Union(ST_Expand(erzmine.the_geom,
2000)),ST_Union(ST_Expand(kaserne.the_geom,2000)))),
ST_Union(
ST_Union(ST_Union(ST_Expand(wohnhaus.the_geom,
2000)),ST_Union(ST_Expand(saegewerk.the_geom,2000))),
ST_Union(ST_Union(ST_Expand(strassen.the_geom,
1000)),ST_Union(ST_Expand(haupthaus.the_geom,6000)))))))
FROM public.grenze_by grenze_by,
public.holzfaeller2 holzfaeller,
public.steinbruch2 steinbruch,
public.erzmine2 erzmine,
public.kaserne2 kaserne,
public.wohnhaus2 wohnhaus,
public.saegewerk2 saegewerk,
public.strassen2 strassen,
public.haupthaus2 haupthaus
GROUP BY grenze_by.the_geom);
I know that the functions are very convoluted, but for me there is no
other way to union/collect the different areas of the buildings.
Please give me some tips how I can solve the problem.
--daniel
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