[pdal] Extract terrain from TLS point cloud

[Silvia Franceschi]

Dear all,
I am trying to extract the ground points from a point cloud of a
terrestrial laser scanner (TLS) in a forestry environment, but the result
is not so good as the one I got using data from ALS.
What I did is:
1. denoise the dataset using the filter.outlier and a filter.range for Z
ranges:
            "type": "filters.outlier",
            "method": "statistical",
            "multiplier": 3,
            "mean_k": 8
2. apply a filter.elm and a filter.smrf to the cleaned dataset
For the SMRF filter I used these parameters:
            "type": "filters.smrf",
            "slope":0.2,
            "window":16,
            "threshold":0.45,
            "scalar":1.2

Unfortunately the resulting ground points contain also the first part of of
the trunks of the trees, how is it possible?

I am doing some testing changing the values of the SMRF parameters but the
results are almost the same.

Do some of you have experience with such kind of data? Am I missing some
operation for filtering? Could you please help me understanding at least
where to focus the attention to try to obtain something...

Thank you in advance.

Silvia


-- 
ing. Silvia Franceschi
Via Roma, 64
38030 Castello di Fiemme (TN)

tel: 0039 -3384501332
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