[pdal] Surface modeling

[Bradley Chambers]

This may be an error. Do please open a ticket. Still, check your output. I
think I saw this too and noted that it wasn’t actually a fatal error, and
that I actually got the output I expected. Something that needs to be
cleaned up regardless.

On Thu, Apr 29, 2021 at 16:15 Andrew Bell <andrew.bell.ia at gmail.com> wrote:

> Andreas,
>
> You'd need to open a ticket and include your exact pipeline in order to
> debug this, but I suspect there is an error in your syntax. Still, the
> error you're getting seems odd.
>
> On Thu, Apr 29, 2021 at 5:01 PM Andreas Yankopolus <andreas at yank.to>
> wrote:
>
>> Bradley,
>>
>> Thanks for your example pipeline. Running it here with pdal 2.2.0, it
>> prints “Parser error = !” when sent a pipeline with these statements. I’ve
>> tracked the error messages to the blocks with "Classification = 6 WHERE …”
>> and "Classification = 4 WHERE  …”.
>>
>> These blocks look valid based one the filters.assign description:
>> https://pdal.io/stages/filters.assign.html
>>
>> For generating the surface height raster, I’d think to write the point
>> with the highest Z value for the raster pixel. For surface type, perhaps
>> label the raster pixel with the most common point classification. I’ll post
>> a first cut.
>>
>> Cheers,
>>
>> Andreas
>>
>>
>> On Apr 28, 2021, at 11:44, Bradley Chambers <brad.chambers at gmail.com>
>> wrote:
>>
>> On Wed, Apr 28, 2021 at 9:34 AM Howard Butler <howard at hobu.co> wrote:
>>
>>>
>>> > On Apr 27, 2021, at 4:11 PM, Andreas Yankopolus <andreas at yank.to>
>>> wrote:
>>>
>>> > Is there previous work in these areas that I can build on with PDAL?
>>> I’m also looking at LAStools, which appears to have binaries that could be
>>> replicated with PDAL pipelines.
>>>
>>> I like to say that "PDAL is something you can use to build LAStools"
>>> about its scope in relation to that product. PDAL isn't pre-canned
>>> workflows for attacking a few kinds of LiDAR processing challenges. It's a
>>> bunch of building blocks for processing point cloud data in the context of
>>> ETL pipelines.
>>>
>>> That said, once constructed, those workflows can be quite valuable.
>>> Fancy classification pipelines haven't typically been shared freely,
>>> however.
>>
>>
>> Your mileage will certainly vary, but one pipeline that was derived from
>> this notebook (
>> https://github.com/rockestate/point-cloud-processing/blob/master/notebooks/point-cloud-processing.ipynb)
>> is shared below. It classifies noise, ground, vegetation, and building
>> returns. In my experience, it does a reasonable job but can still require
>> fine tuning of the parameters.
>>
>> [
>>     {
>>         "type": "filters.assign",
>>         "assignment": "Classification[:]=0"
>>     },
>>     {
>>         "type": "filters.elm"
>>     },
>>     {
>>         "type": "filters.smrf",
>>         "where": "Classification != 7"
>>     },
>>     {
>>         "type": "filters.hag_delaunay"
>>     },
>>     {
>>         "type": "filters.outlier",
>>         "multiplier": 16,
>>         "class": 18,
>>         "where": "!(Classification==2 || Classification==7)"
>>     },
>>     {
>>         "type": "filters.approximatecoplanar",
>>         "where": "HeightAboveGround >= 2 && !(Classification==2 ||
>> Classification==7 || Classification==18)"
>>     },
>>     {
>>         "type": "filters.outlier",
>>         "class": 18,
>>         "where": "!(Classification==2 || Classification==7 ||
>> Classification==18) && Coplanar == 1"
>>     },
>>     {
>>         "type": "filters.assign",
>>         "value": "Classification=6 WHERE (Coplanar == 1 &&
>> !(Classification == 7 || Classification==18))"
>>     },
>>     {
>>         "type": "filters.covariancefeatures",
>>         "mode": "normalized",
>>         "feature_set": "Dimensionality",
>>         "knn": 45
>>     },
>>     {
>>         "type": "filters.assign",
>>         "value": "Classification=4 WHERE (!(Classification==2 ||
>> Classification==6) && HeightAboveGround >= 3.0 && Planarity < 0.8 &&
>> Scattering > 0.1 && Verticality > 0.1)"
>>     }
>> ]
>>
>>
>> _______________________________________________
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>> pdal at lists.osgeo.org
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>>
>
>
> --
> Andrew Bell
> andrew.bell.ia at gmail.com
>
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