[postgis-devel] [raster] UML Diagram, seamless vector/raster access

[Bryce L Nordgren]

"Iteration 2" has been incarnated as the definition of a "SpatialCollection"
type and added as a UML diagram to the end of:

http://trac.osgeo.org/postgis/wiki/WKTRaster/SeamlessArchitecture

The intent is to provide an implementation of Set<CV_GeometryValuePair> from
ISO 19123, with some behavior useful for some problems at hand.

Hopefully, this will be less ambiguous than my numbered list of features.
This set of features can "wrap" either a vector or a raster dataset and
provide a consistent means to access two important pieces of information:

1] Is the provided point contained in the data set?
2] What is the value of the data set at the provided point?

Again, the relationships (solid arrows) in the diagram will be implemented
with function pointers, as will the operations in implementations of the
"CollectionContains" and "CollectionEvaluate" interfaces. An interface
object for each input will be initialized with the correct combination of
implementations at the beginning of the function, and used for the iteration
over each pixel. A "wrapper" for the raster result will also be initialized
at the beginning of the function, and should be capable of providing the two
vital pieces of information for the result at arbitrary locations. The grid
iteration engine, then, merely samples the information from the result
wrapper and stores it in the output raster.

Let me know if you spot any fatal flaws...
Bryce
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