[pdal] Filtering atmospheric noise

[Kirk Waters - NOAA Federal]

Withheld is a flag, not a class. They would likely be both class 1 and
withheld. There should be a way to ignore withheld points.

On Wednesday, March 9, 2022, Andreas Yankopolus <andreas at yank.to> wrote:

> They’re mostly marked at 1 (unclassified) but I’ve seen a few that are 11
> (road surface)!
>
> On Mar 9, 2022, at 17:05, Kirk Waters - NOAA Federal <kirk.waters at noaa.gov>
> wrote:
>
> Is there any chance the points are marked as withheld? I've seen quite a
> bit of data where bad points are marked as withheld but not marked as noise.
>
> Kirk Waters, PhD
> NOAA Office for Coastal Management
> Applied Sciences Program
> ‪Phone: 843-284-6962‬ (New as of 2022)
> coast.noaa.gov/digitalcoast
>
>
>
>
> On Wed, Mar 9, 2022 at 4:45 PM Andreas Yankopolus <andreas at yank.to> wrote:
>
>> All—
>>
>> I’m using USGS 3DEP point-clouds to generate surface-height rasters
>> around Longmont, CO. The point-cloud files have spurious returns over many
>> of the lakes/reservoirs in the area that are tagged other than 7 or 18.
>> They’re streaks about 0.3 m long located 200+ m above the lake. In most
>> cases the streak has 3–8 points, but I’ve found one with 34 points.
>>
>> The outlier filter with statistical or radius methods doesn’t remove
>> these longer streaks. Any recommendations on removing dense groups of
>> points well separated from the main mass?
>>
>> I’m having success with:
>>
>> {
>>
>> "type": "filters.outlier",
>>
>> "method": "radius",
>>
>> "radius": 16.0,
>>
>> "min_k": 64
>>
>> }
>>
>>
>> This seems to do the trick of removing isolated groups while leaving the
>> main body of points alone, but I’m thinking these some other dimension that
>> could be calculated and added to points then used to remove outlier groups
>> later.
>>
>> Cheers,
>>
>> Andreas
>> _______________________________________________
>> pdal mailing list
>> pdal at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/pdal
>>
>
>

-- 
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