[pgpointcloud] Dimensions and CRS

[Paul Ramsey]

> 1) The default PDAL schema has got 14 dimensions when reading from las and writing to postgres. I only want to have 3 default dimensions (X,Y,Z) and want to add two more dimensions. I am using selector filter to keep XYZ and create two new dimensions. I want to know how to assign a default value for the new dimension. One of the newly created dimension is PointID (I tried to mimic the PointID dimension from default PDAL schema) but I don’t know how to assign point identifier to each point when I am not making use of default PDAL schema. Do you know how does the default value for PointID gets assigned?
I don't know the answer to this one... I feel like I've seen an example of pointid being assigned in a PDAL pipeline though... maybe in the examples in the test directory?

> 2) When I create a table with the data type PcPatch, I have to specify pcid from predefined pointcloud_formats table. I am wondering whether the table of type PcPatch only supposed to handle one SRID? Can I store PcPatches of different SRIDs into the same column?
The assumption is that each PCID contains only a single SRID. I don't think storing mixed-SRID columns is a wise idea, for the same reason it's not a good idea in PostGIS (makes spatial searches hard/inefficient)

P