[Qgis-developer] Postgis Pointcloud support

[Ziegler Stefan]

Hi Martin

From my point of view there is one big advantage of having LiDAR point clouds in a database: SQL (or probably more precise DML). No more system calls or different programs to solve a problem. Just pure SQL. One interface to rule them all: vector processing? SQL. Raster processing? SQL. Point cloud processing? SQL. Combining them all together? SQL.

I tested Paul Ramseys work [1] with our own data. It’s really great and comfortable to work with. But can’t say much about performance. I needed to work on a really slow fanless celeron pc with a slow harddrive.

[1]: http://workshops.boundlessgeo.com/tutorial-lidar/

Regards
Stefan

Von: Martin Isenburg [mailto:martin.isenburg at gmail.com]
Gesendet: Freitag, 24. Juli 2015 11:55
An: Tim Sutton
Cc: Ziegler Stefan; QGIS Developer Mailing List
Betreff: Re: [Qgis-developer] Postgis Pointcloud support

Hello,

I am a bit hesitant to recommend inserting LiDAR point clouds into a database (because I believe - for LiDAR or dense-matching points -- you should just only insert the shapefile outlines into a database and then run a las2las query on those spatially indexed (amd possibly resorted) LAS / LAZ  files whose outlines overlap the queried area) as this has shown not to be very performant in a large study by TU Delft involving many different spatial databases ... but in some use cases it may make sense. The papers and relevant discussions are linked here:

http://groups.google.com/d/topic/lastools/MoYPFzFVxa8/discussion
http://groups.google.com/d/topic/lastools/jkB1UK5DxN4/discussion

That said ... one case where it may make sense is when you insert once and then look-up *a lot* in small batched. Something like what Yuriv Czoli from developmentseed did will give you some pointers to get started:

http://developmentseed.org/blog/2014/08/07/processing-lidar-point-cloud/
http://gist.github.com/YKCzoli/3605e014b8ed09a571e5

Regards,

Martin

On Thu, Jul 23, 2015 at 8:11 PM, Tim Sutton <tim at kartoza.com<mailto:tim at kartoza.com>> wrote:
Hi



On 22 Jul 2015, at 09:39, Ziegler Stefan <Stefan.Ziegler at bd.so.ch<mailto:Stefan.Ziegler at bd.so.ch>> wrote:

Hi

I just read in the changelog that there is some postgis pointcloud layers support? What does this mean? Can I load e.g. the patches as polygon into QGIS?

I tried to replicate / test etc. when working on the changeling, and couldn’t figure out how to make it do anything useful, get hold of a usable test dataset etc. Hopefully someone out there will write up a little tutorial or something.

Regards

Tim


Regards
Stefan

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