[Gvsig_english] clean polygon? Issue with layers imported from Oracle Spatial

[Wolfgang Qual]

Dear list,
I wonder whether you have observed "bleeding" polygons - this seems to 
be an effect that only occurs when using ArcView 3.2 - bleeding means 
that borders of
a polygon are ignored and the whole area of the view is filled. This 
happens when zooming into the view and it seems to indicate that the 
shapefile has some errors.
Within ArcView, shapefiles can be "repaired" using the command 
[Shape].clean. From the manual of ArcView:

"Clean Polygon
Returns a Polygon that has the same vertices as aPolygon but is "clean". 
A clean polygon is one that:
1. Has no self-intersections. This means that a segment belonging to one 
ring may not intersect a segment belonging to another ring. The rings of 
a polygon can touch each other at vertices, but not along segments.
2. Has the inside of the polygon on the "correct" side of the line which 
defines it. The neighborhood to the right of an observer walking along 
the ring in vertex order is the inside of the polygon. Vertices for a 
single, ringed polygon are, therefore, always in clockwise order. Rings 
defining holes in these polygons have a counter-clockwise orientation. 
"Dirty" polygons occur when the rings which define holes in the polygon 
also go clockwise, which causes overlapping interiors."

These bleeding polygons especially appear with polygon layers that were 
exported from our oracle spatial geodatabase - with gvSIG 1.9. However, 
the "bleeding"-effect is only visible in ArcView, not gvSIG. Therefore, 
one could say that this is not a real problem, just use gvSIG! Well, 
this is not a good advice, as other departments/users are using 
ESRI-solutions. I do not know what errors are causing this strange 
bleeding effect, maybe someone of you knows why this is happening. The 
command "clean" does help, but it is not available within gvSIG. Last 
week, we found out that a layer created within gvSIG is rendered with 
errors using the UMN Mapserver, although no errors are visible in gvSIG 
([1], the first layer shows a narrow triangle) . If this layer is loaded 
into ArcView 3.2, the bleeding effect can be observed. Once "clean" is 
applied, the error will be fixed - both in ArcView AND UMN Mapserver.

Therefoe, I would like to ask, a) whether this "bleeding" problem is 
known and b) whether a "clean"-function is foreseen for gvSIG - or could 
be implemented.

Any comments are appreciated very much.
Best,
Wolfgang
 
[1] 
http://maps.muenchen.de/rgu/test_bplan_shape?zoom=9&lat=5334209.93813&lon=4459255.64274&layers=B00TTT
-- 

	*Wolfgang Qual

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