[pdal] Is PDAL capable of producing Lidar grid metrics?

[Jean-Francois Prieur]

Believe he is trying to move entirely to Linux and is looking for a FUSION
metrics replacement since it does not run in Linux. SPDLib looks
interesting. If you have access to LAStools the LAScanopy tool does these
metrics, although I am unsure if the free version has full functionality.

On Thu, Sep 1, 2016 at 9:42 AM Howard Butler <howard at hobu.co> wrote:

> As I mentioned in the Stack Exchange thread, and Brad mentioned below,
> this isn't currently possible out of the box with PDAL. I would ask what
> you are hoping to get by having this capability in PDAL rather than
> building a tool chain that includes FUSION + PDAL + other tools. Maybe it
> would be helpful to take a step back and describe how PDAL statistics
> computation would fit within a larger context.
>
> Most of PDAL's current "characterization" filters are about generating
> primitive computations for algorithms such as slope, ground, etc. There's
> things like coplanarity, projection, regression, sampling, and normal
> computation [1]. These are "per-point" type statistics rather than
> summaries, however, and are focused on the positional geometry of the point
> in relation(s) to its neighbors. Brad described the derivative writer,
> which does some typical surface summaries, and it would be a good place to
> start on an implementation if you were sufficiently motivated.
>
> PDAL's statistics filter [2] was recently updated to add kurtosis,
> skewness, variance, etc (no percentiles). You *might* be able to use that
> in combination with some sort moving window bounding geometry along with
> the crop filter [3], but this would be quite laborious and probably quite
> slow. Rémi's pgpointcloud approach seems viable and might be useful for
> other reasons, depending on what you want to do.
>
> So, plenty of options but nothing that just does it.
>
> Howard
>
> [1] http://www.pdal.io/stages/filters.html
> [2] http://www.pdal.io/stages/filters.stats.html
> [3] http://www.pdal.io/stages/filters.crop.html
>
> > On Sep 1, 2016, at 8:37 AM, Bradley Chambers <brad.chambers at gmail.com>
> wrote:
> >
> > Aaron,
> >
> > This is absolutely possible; it just doesn't exist out of the box today.
> We do something similar in our DerivativeWriter today (
> https://github.com/PDAL/PDAL/blob/master/io/derivative/DerivativeWriter.cpp).
> That may be a good place to look for inspiration. I think in the end you
> are looking for a GridMetricsWriter though. Are you needing a full
> replacement of the FUSION function? Or just a few select metrics?
> >
> > Brad
> >
> > On Thu, Sep 1, 2016 at 9:22 AM Aaron Poznanovic <aaron at redfoxgis.com>
> wrote:
> > Greetings,
> >
> > This is a follow-up to a question posted over at GIS Stack Exchange (
> http://gis.stackexchange.com/questions/175454/are-pdal-or-pcl-capable-of-producing-lidar-grid-metrics).
> I'm curious what functionality or approach one would take with PDAL to
> calculate Lidar grid metrics?
> >
> > FUSION is currently the best available set of tools that I know of for
> calculating Lidar grid metrics, which are useful for describing forest
> structure (http://forsys.cfr.washington.edu/fusion/fusionlatest.html).
> From the FUSION documentation (page 70 from the documentation
> http://forsys.cfr.washington.edu/fusion/FUSION_manual.pdf):
> >
> > GridMetrics computes a series of descriptive statistics for a LIDAR data
> set. Output is a raster (grid) represented in database form with each
> record corresponding to a single grid cell.
> >
> > Essentially, I'm interested in producing a raster dataset where each
> cell represents summarized descriptive statistics for the Lidar point cloud
> such as cover, skewness, 75th percentile, etc (all of the grid metrics I'm
> after are available on the FUSION documentation. Is this currently
> possible, or recommended, with PDAL, or would this require other libraries?
> Many thanks in advance.
> >
> > Best Regards,
> >
> > -Aaron
> >
> > Currently
> >
> >
> > Aaron J. Poznanovic, GISP
> > Principal Consultant
> > Red Fox GIS & Remote Sensing
> > (218) 387-4050
> > www.redfoxgis.com
> >
> >
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