[pgpointcloud] Nature of patches

[Howard Butler]

On Jul 9, 2014, at 7:40 AM, Stephen Mather <stephen at smathermather.com> wrote:

> Hi Howard,
> 
> The other reason for the question, is I'm interested in vertical parsing of the point cloud, splitting the cloud into height classes e.g. every 10 ft, so understanding whether PDAL's chipper was already splitting on the Z-axis was something important to understand.

Do you want an actual octree? It might make more sense to arrange the data that way, and then store the nodes as PC_patch instances. There's nothing in PDAL or pgpointcloud to do that now, but it should be straightforward to implement.

Otherwise, what I would do is create a series of different pipelines that use the filters.predicate to filter out what Z's you want for each slide. Chip that, and then load it into pgpointcloud. What is the state of PostGIS's 3D indexing these days? Will it allow you to model the chip/cube as a solid and query accordingly?

We could add some functionality to the chipper to allow you to set which dimensions you want to use as the X and Y. This would allow you to flip the orientation of the data as it is chipped. I don't know exactly what this gets you, but it would be possible and easy to do.

Howard