Minimum bounding rectangle of a single geometric feature

Question

Is there a function in ORACLE Spatial 8.1.7 that returns the
minimum bounding rectangle (MBR) of a single geometric feature?
SDO_TUNE.EXTENT_OF returns a MBR but for the whole layer but not
for a single geometry.

Answer 1

Hi,
This is much slower than the built-in function for 9i, but might
be helpful in any event. This function only works for 2d
geometries. It doesn't do error checking for points and such.
It assumes a NULL SDO_SRID. Etc. It isn't supported. In 9i, I'd
immediately suggest going to sdo_geom.sdo_mbr.
Call it like this:
select xmbr(geom) from geod_states where state_abrv='NH';
create or replace function xmbr (geom mdsys.sdo_geometry)
return mdsys.sdo_geometry is
vmbr mdsys.sdo_geometry;
ogg mdsys.sdo_geometry := geom;
ii number;
xlow number;
xhigh number;
ylow number;
yhigh number;
begin
-- initialize it
xlow := 999999999999;
ylow := 999999999999;
xhigh := -999999999999;
yhigh := -999999999999;
-- assumes 2d geometry
for ii in 1..ogg.sdo_ordinates.count
loop
if mod(ii, 2) = 0 then
-- y
if ogg.sdo_ordinates(ii) > yhigh then
yhigh := ogg.sdo_ordinates(ii);
else
if ogg.sdo_ordinates(ii) < ylow then
ylow := ogg.sdo_ordinates(ii);
end if;
end if;
else
-- x
if ogg.sdo_ordinates(ii) > xhigh then
xhigh := ogg.sdo_ordinates(ii);
else
if ogg.sdo_ordinates(ii) < xlow then
xlow := ogg.sdo_ordinates(ii);
end if;
end if;
end if;
end loop;
-- build the object (MBR rectangle)
vmbr := mdsys.sdo_geometry(2003, null, null,
mdsys.sdo_elem_info_array(1,1003,3),
mdsys.sdo_ordinate_array(xlow, ylow,xhigh, yhigh));
return vmbr;
end;