SDO_RELATE_2

Question

Hi,
I have created a polygonshape and a line shape with Arcmap. The polylines (5) were snapped to the polygons so they are exactly on the same place as the polygon. 4 lines are equal to a part of the polygon (snapped on the vertices), a fifth is a bit shorter then the part of the polygon on which it is placed (and therefore not snaped to vertices but to the line). All the geometries then were loaded to oracle spatial, useing SDE. When I tried to determine the relation between all the polylines and one of the polygons I found that the relation between the fifth line and the polygon is:
'OVERLAPBDYDISJOINT'
I expected it to be:
'ON' (as shown in les07.ppt from spatial_training_817.zip, slide 14, left corner)
The query I used is:
select mdsys.sdo_geom.relate (lnn.geometrie, 'determine', ovl.geom, 0.000001)
, lnn.id lijn_id
from overlap_perc ovl
, lijn_test lnn
where ovl.id = 3
overlap_perc is a polygon layer
lijn_test is a line layer
What am I doig wrong here? why isn't the relation 'ON' while he les07.ppt suggests it should be?

Answer 1

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Siva Ravada:
Gerjan,
There are some tolerance related issues
here.
I am not sure you got the complete precision
of the numbers in the coordinates you
gave here.
If these are the actual coordinates:
(i) The tolerance of 0.000001 is very small.
With that tolerance the line is
completely inside the polygon.
And I get 'INSIDE'
relationship in 9i.
(ii) If I use a tolerance of 0.005, I get
'COVEREDBY' in 9i.
(iii) Even (ii) is not the right relation.
We did some more tolerance fixes
in the current release cycle.
You would get 'ON' with 0.005 in
9i second release (9.0.2).
But you will still get 'INSIDE' with a tolerance of 0.000001.
<HR></BLOCKQUOTE>
Hi Siva,
Thank you for your reply. I agree with you that the tolerance is very small. So I changed the tolerance to:
with tolerance 0.005 the line (with id = 100) is still inside.
I have set the tolerance to 5 now. This resulted in a touch, but according to the coordinate system I use (Dutch System) this tolerance is 5 meters which is far too much for our goal. Besides that: 'Toch' is also not the correct relationship.
Do you think that I have to conclude that determining the relation between the line and ploygon is not going to work, when useing release 8.1.7? Or this conclusion to premature?
null