[postgis-users] Point cloud questions (PC NEWBIE here)

[Rémi Cura]

Hey,
I'm not M.Ramsey,  I'm just a pointcloud user.

1. : you can "colorize" based on any attributes of points. Traditional
point cloud softwares expect usually R G B attributes, but for some you can
choose which attributes to use for coloring (CloudCompare).

2 : We have thought about visualisation (in this area it's about Level Of
Details). The best we tried (because of lack of time) is to make another
PC_Explode so it returns only a certain number of points per patch.

The next step is to writte points in patch following a quad tree structure
(not deep first but breadth-first) (maybe using
http://www.postgresql.org/docs/9.3/static/spgist-examples.html , not sure
about this).
This way when taking only the first XX points in patches, you ensure these
points are always well distributed in the patch.

This is the best we thought of without duplicating data (not an option with
so big data anyway).

3 : about générating a raster from pointcloud :
You can do it in QGis , Grass Gis, or using GDAL or LasTool. (also in
CloudCompare) Usually you have access to sophisticated interpolation
methods (square inverse distance, etc etc). It is a hard problem in
practice because of memory limitation and possible multiple holes in data.


Please feel free to ask if you want more details.

Cheers,

Rémi-C




2013/10/18 Basques, Bob (CI-StPaul) <bob.basques at ci.stpaul.mn.us>

>  Hi all,****
>
> ** **
>
> Juat watched Paul Ramseys video on point cloud storage and it made me
> think of a few questions to ask.****
>
> ** **
>
> Quesitions:****
>
> **·          **Sort of a DB processing question, probably not thought
> about yet, but can the pointcloud be colorized based on a raster/vector of
> view passed in?  As in aerial photos obviously, but less obvious would be
> for oblique photos.  ****
>
> **·          **Generalizing of the pointclouds, from my perspective to be
> used for zoom in/out processes for visualization.  Could a average height
> based on a (pyramid) tiling possibly be used to get close to a generalizing
> scheme, I know this approach might offend purists as far as data integrity
> . .****
>
> **·          **There was a question in the video that I watched related
> to building a surface grid from the pointcloud, I wonder about a simple
> tile averaging as a method for generating a grid.  Anyone tried and have
> available some benchmarks for this idea?****
>
> ** **
>
> Thanks****
>
> ** **
>
> Bobb****
>
> ** **
>
> ** **
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20131021/9d82b1de/attachment.html>