On Fri, Jan 21, 2011 at 4:56 PM, Justin Deoliveira <jdeol...@opengeo.org>wrote:
> Great work indeed! Very impressive and well designed. Big +1 here. However
> as a rendering/styling/etc... novice I do have some basic api questions.
>
> Excuse my ignorance but in the RenderingTranformation and RenderingProcess
> interfaces why do the invertQuery methods meant for vector data take a
> GridGeometry? Where does this come from?
>
The grid geometry represent the structure of the output, puts together the
output width/height with the
output envelope. It is meant to be used by processes that do a vector to
raster conversion.
Take the heatmap case, you have a set of vectors (I guess points) and want
to generate a raster
output that will be then depicted to show the density/concentration of the
input phenomena.
In that case the method will generate a query that will catch all of the
points needed to build
the heatmap in that area (which might require to grow the query area
somewhat),
maybe shaving off the points that are known to have no effect on the heapmap
building (the
ones that have the attribute used to build the heatmap at 0).
For that case you'd just need the output envelope, not the
full GridGeometry, but I can't know
exactly what the process will be doing so I'm giving it all the information
it may possibly need.
>
> Also the invert methods. If I read it correct there job is take a query
> made by a user and morph it ensure that it includes the data needed to
> perform the transformation? When i see inversion I think of changing
> something to be opposite or reversed. IS that the case here?
>
I chose the name to be consistent with the geometry transformations, that
also have an invert method.
Whether it's going to be a real inversion or not, it depends.
A process that buffers geometries will actually have to also buffer the
query area, since there might be
geometries outside of the area that once buffered do cross it (this is not
actual inversion)
A process that takes an attribute and multiplies it by 2 (for the same of
the example) will have to
take a filter like attribute > 100 and turn it into attribute > 200 (actual
inversion)
Cheers
Andrea
--
Ing. Andrea Aime
Technical Lead
GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584962313
fax: +39 0584962313
http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
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