[pdal] Python and chipper filter

[Andrew Bell]

The chipper filter creates sets of points for each tile.  These sets
(called point views) pass through the pipeline individually and are
processed separately by each downstream filter.  In your case, the chipper
should create two or three point views (since the count limit on the points
is 10,000 and the capacity limit on the chipper is 5000 points).  This
essentially means that the python filter gets invoked two (or three)
times.  When you reverse the order of the python filter and the chipper,
the python filter is only invoked once, since at that point in the
processing, only one point view exists.

All that said, the differences you're seeing seem extreme and I think it
would take more investigation to figure out the root cause of the timing
differences.

On Mon, Sep 10, 2018 at 3:47 AM Lars <laasunde at hotmail.com> wrote:

> Hello,
>
> We have created a pipeline with a python script but are seeing some
> unexpected behaviour. The python script currently does nothing to exclude
> the script as culprit.
>
> Running the script with 10k count and pipeline is completed in less than a
> seconds. Increasing to 50k count and it takes to 2 seconds but increasing
> to 80k count suddenly it takes 150 seconds!!! Attempting to use 90k count
> and after 25 minutes it is still not finished (pdal is constantly using
> 12,5% --> one core).
>
> If we changed the order of the filters (python first and then chipper),
> then 10k count took less then a second and 100k takes 4 seconds.
>
> If we remove the python filter then 10k count took less then a second and
> 100k takes 4 seconds.
>
> This appears to be related to the python filter.
>
> Why is the the attached pipeline so slow? Is this a software issue or
> poorly designed pipeline?
>
> Using PDAL 1.7.2 on Windows 10.
>
> kind regards, Lars
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-- 
Andrew Bell
andrew.bell.ia at gmail.com
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