[Gvsig_english] spatial query rules in Selection by layer tool

[Lucía Martínez]

Hello Ernesto,
I was also testing every option of the tool.
I am afraid but we do not have enough documentation to determine the 
exact behavior of some of the options.
As you say, they may need some adjustments.

-- 
Lucía Martínez Palomero
Proyecto gvSIG
Consellería de Infraestructuras y Transportes (GVA)
Valencia (Spain)



El 18/05/11 14:08, ernesto sferlazza escribió:
> Hello users and developers
> I have performed some trials to test how actually work the various
> operators (or topological rules) implemented in the "spatial
> selection" tool .
>
> - Operators "are the same as" and "intersect with": they works as I
> expected for all kinds of geometries.
>
> - Operator "are disjoint from": the spatial query  returns an error
> (java.lang.NullPointerException) when I compare input layers
> (polygons, lines or points)with  polygons  selected in a mask layer.
> If I compare an input layer with features selected in the mask layer
> (lines or points), the spatial query performed with the above
> mentioned topological criterion  returns all feature from the input
> layers, despite some of them touch or intersect almost one feature of
> the mask layer.
> Maybe I have not understood its correct meaning: how really it should works?
>
> - Operator "touch": points (in the input layer) are selected if they
> touch a vertex (but not simply the edge) of a polygon (in the mask
> layer)or one of the endpoints (but not other intermediate vertices) of
> a line feature (in the mask layer). If the mask layer is a point
> layer, no feature is selected from point input layer even if we have
> coincident points.
> Lines from the input layer result selected if one of their endpoint
> touch, in the mask layer, the endpoint (not an intermediate vertex) of
> a line feature , or a single point, or a vertex (not simply the edge)
> of the boundary of a polygon feature.
> Using a polygon layer as input and a polygon layer as mask, "touch"
> select only polygons for which only a segment (side) of the perimeter
> of the input polygon is contained in a larger segment of the mask
> polygon, but not the reciprocal (very strange behaviour); if the rest
> of the input polygon overlaps the mask polygon, no selection occurs.
> Using polygon layer as input and line layer as mask, the polygons
> selected by "touch" are those for which lthe line (mask) feature lies
> entirely on the perimeter of the polygon or if the end of the line
> touches the vertex of the polygon and the line is not overlapped to
> the interior of the polygon.
> Using polygon layer as input and point layer as mask, polygons are
> selected if one vertex of the perimeter is coincident with one point
> of the mask layer.
>
> -Operator "cross over": lines (input) are selected if an endpoint
> touches the edge or the interior (not the vertex) of a polygon (mask),
> or if any point of the line touches a vertex of a polygon, but not if
> an intermediate vertex of the line touches the edge of a polygon or if
> only the endpoint of the line touches the vertex of a polygon.
> [...] to be continued
>
> Have I misunderstood something on how operators work, or really some
> adjustment to the rules of spatial query are needed?
>
> Best regards
>


-- 
Lucía Martínez Palomero
Proyecto gvSIG
Consellería de Infraestructuras y Transportes (GVA)
Valencia (Spain)