[pgpointcloud] Nature of patches

[Stephen Mather]

Hi Howard,

An octree as in a 3D octree? That could be very powerful, It would still
arrange the points in a chip close to each other vertically, while allowing
for vertical stratification.  I think I could definitely see uses for that.

3D indexing is pretty good, I think, in the limited tests I've done with
it. Makes me wonder what a 3D r-tree looks like, actually.

"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 understand the first sentence-- that would be brilliant. I'm not sure the
meaning of second.

Best,
Steve






On Wed, Jul 9, 2014 at 9:40 AM, Howard Butler <howard at hobu.co> wrote:

>
> 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
>
>
>
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