[Liblas-devel] Las2Oci problems

[Howard Butler]

On Apr 15, 2011, at 8:01 AM, T.J.F. Commandeur wrote:

> Hi all,
>  
> For scientific research I created another kind of Lasblock based on spatial finalization by M. Isenburg (spfinalizer).
> This program is able to process larger point clouds and has a low memory footprint based on a quadtree structure.
> When the program is done it creates either separate las files for every block or a las and kdx file.
> Now these are created I want to load them to an Oracle spatial SDO_PC with Las2Oci.
> I am using libLAS from OS4geo on windows, during the usage of Las2Oci I found some strange things.

Excellent!  I'm glad you found the code useful in some way.

> -          When writing las to a database using a kdx file Las2Oci tends to duplicate the last block written to the database (kdx created by Lasblock).

* Thanks for finding this.  It must be a bug.

> -          Las2Oci loads the complete kdx file into memory which seems quite insufficient for memory usage. Can’t the kdx be read line by line (block by block) instead of completely at once?

* Yes, it could be made to do this. That it doesn't is because it was going to be approached later when it became a problem.

> -          When executing Las2Oci without a kdx file but with multiple las files it creates a new point cloud for every file. There is no option to add new blocks to an existing point cloud instead when using multiple las files.

We would need a patch to fix this.

>  
> Is there a solution to these problems? Do I need to change my workflow for using Las2Oci to indeed add las files to an existing point cloud in the database?

I have been working on the OCI stuff under a different framework that Michael Gerlek and I have been developing called libPC.  It's intent is more of a "GDAL for Point Clouds" with things arranged in a processing pipeline. This has a number of advantages over the libLAS OCI efforts, which are quite tied to LAS. The lasblock code is available as a "filter" within this pipeline, and it would be conceivable for you to make a filter using your modified spfinalizer code as well if this is something you are interested collaborating on.

http://hg.libpc.org/main is where the code lives.  It is quite rough in many ways, and there are definitely no prebuilt windows binaries that can consume those kdx files yet, but the basics of OCI reading and writing are there.

Howard