On Fri, Jan 21, 2011 at 9:52 AM, Andrea Aime
<andrea.a...@geo-solutions.it>wrote:
> 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.
>
Cool makes sense.
>
>
>>
>> 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)
>
Gotcha. Makes sense. Thanks for the info.
>
> 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/
> http://www.linkedin.com/in/andreaaime
> http://twitter.com/geowolf
>
> -----------------------------------------------------
>
--
Justin Deoliveira
OpenGeo - http://opengeo.org
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