[pdal] Possible bug related to forked pipelines

[Kristian Evers]

Thanks, Andrew. I’m subscribed to the ticket you just created and will make sure to test as well when you have a fix.

I agree that forked pipelines are a complicated affair, but it can also be a very powerful tool if  you know what you are doing.
I don’t expect PDAL to hold my hand in that regard!

/Kristian

Fra: Andrew Bell [mailto:andrew.bell.ia at gmail.com]
Sendt: 14. november 2016 15:40
Til: Kristian Evers
Cc: pdal
Emne: Re: [pdal] Possible bug related to forked pipelines

The particular report is a bug in parsing the pipeline.  However, handling a pipeline that forks is tricky.  I think we take a hands-off approach, which means that unless you're careful, you may not get the behavior you expect.  I'll fix the bug, test and report back.

On Mon, Nov 14, 2016 at 6:33 AM, Kristian Evers <kreve at sdfe.dk<mailto:kreve at sdfe.dk>> wrote:
Hi.

I have a few use cases where it would be beneficial to create a forked pipeline, i.e. one that generates
several outputs from the same input-file, but I am having some trouble achieving that.
If I understand the documentation correctly it should be possible by using the tags and inputs keywords
in a pipeline. Something like this:

{
  "pipeline":[
    {
        "type": "readers.las",
        "filename": "input.las",
        "tag": "A"
    },
    {
        "inputs": "A",
        "type": "writers.gdal",
        "resolution": 0.4,
        "radius": 0.7,
        "filename": "Z.tif",
        "dimension": "Z",
        "output_type": "mean
    },
    {
        "inputs": "A",
        "type": "writers.gdal",
        "resolution": 0.4,
        "radius": 0.7,
        "filename": "intensity.tif",
        "dimension": "Intensity",
        "output_type": "mean"
      ]
}

That is, use the new gdal writer (which is awesome, btw) to grid two or more dimensions of a las-file.
When I run this particular pipeline I get the following error:

“PDAL: writers.gdal: specified dimension 'Intensity' does not exist.”

which suggests that the last writer (intensity.tif) is trying to grid a dimension from the first writer
(Z.tif) instead of input.las. This is a bit confusing since I specifically instruct PDAL to read
from tag A defined in the first stage of the pipeline. Is this a bug or just me trying to do something
I was never meant to do?
I am working on a Windows 7 computer and PDAL was compiled with VS2015 from a fairly
new revision (2f57c0cf1703af51498f9dae71c9a70128c4c93a).


Regards,
Kristian

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--
Andrew Bell
andrew.bell.ia at gmail.com<mailto:andrew.bell.ia at gmail.com>
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