To Do
=====

- (?) convert PCBYTES to use PCDIMENSION* instead of holding all values as dupes
- (??) convert PCBYTES handling to pass-by-reference instead of pass-by-value
- implement PC\_PatchAvg/PC\_PatchMin/PC\_PatchMax as C functions against patches with dimensional and uncompressed implementations
- TESTS for pc\_patch\_dimensional\_from\_uncompressed() and pc\_patch\_dimensional\_compress()
- Add in dimensional stats caching to speed up dimensional compression in batch cases

- Add Min/Max values to dimensional compression serialization (???)
- Add Min/Max values to GHT compression serialization (???)

- Update pc\_patch\_from\_patchlist() to merge GHT patches without decompression
- Update pc\_patch\_from\_patchlist() to merge dimensional patches directly

- Before doing dimensional compression, sort by geohash (actually by a localized geohash based on the patch bounds). This will enhance the autocorrelation of values and improve run-length encoding in particular
- Add Min/Max values to front of GHT serialization

Use Cases to Support
--------------------

- frustrum filtering
- raster overlaying
- filtering on attribute values
- filtering on spatial polygons (in *and* out)
- find the k nearest points to point P
- gridding/binning ("avg intensity per cell", "max z per cell", "agv red per cell", "rgb into grid/picture")
- reprojection / re-schema

More Functions
--------------

- PC\_FilterEquals(patch, dimension, value) returns patch
- PC\_FilterLessThan(patch, dimension, value) returns patch
- PC\_FilterGreaterThan(patch, dimension, value) returns patch
- PC\_FilterBetween(patch, dimension, valuemin, valuemax) returns patch
- PC\_FilterPolygon(patch, wkb) returns patch
- PC\_Filter(patch, dimension, expression) returns patch
- PC\_Get(pcpatch, dimname) returns Array(numeric)

- PC\_Transform(pcpatch, newpcid)