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I am trying to read and write LAS (*.las) file using PDAL but getting the following warning messages by PDAL's LAS reader and writer for ASPRS LAS files.

(pdal pipeline readers.las Warning) C:/denoise\lake.las: 
      Found invalid value of '0' for point's return number.

(pdal pipeline readers.las Warning) C:/denoise\lake.las: 
      Found invalid value of '0' for point's number of returns.

I'm trying to remove noise from las file using the code below:

 { "pipeline":[ "C:/denoise/lake1.las", { "type": "filters.outlier", "method": "statistical", "multiplier": 3, "mean_k": 8 }, { "type": "filters.range", "limits": "Classification![7:7],Z[-100:3000]" }, { "type": "writers.las", "compression": "true", "minor_version": "2", "dataformat_id": "0", "filename":"C:/denoise/clean.las" } ] }
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  • You need to be more specific about "not being done correctly" with some more information as to why you think this is the case. Commented Jul 27, 2017 at 1:55
  • I'm trying to remove noise from las file using the code below; { "pipeline":[ "C:/denoise/lake1.las", { "type": "filters.outlier", "method": "statistical", "multiplier": 3, "mean_k": 8 }, { "type": "filters.range", "limits": "Classification![7:7],Z[-100:3000]" }, { "type": "writers.las", "compression": "true", "minor_version": "2", "dataformat_id": "0", "filename":"C:/denoise/clean.las" } ] }
    – Hassam Ali
    Commented Jul 27, 2017 at 5:16

1 Answer 1

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(pdal pipeline readers.las Warning) C:/denoise\lake.las: Found invalid value of '0' for point's return number.

'0' is not a valid return number in LAS, and PDAL is just warning you here about it. It should pass it on through without touching it though.

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  • But the output file that pdal creates in this case is of 1KB and the same code removes noise from laz file correctly.
    – Hassam Ali
    Commented Jul 27, 2017 at 9:49
  • I've figured out that the point cloud has been created from stereo pairs thus there will be no return of the beam information with the points.
    – Hassam Ali
    Commented Jul 31, 2017 at 14:59
  • "It should pass it on through without touching it though". Here @abellgithub is proposing to coerce 0 to 1 when reading it into PDAL and leaving a warning message. This was not implemented, right? Commented Aug 7, 2017 at 1:37
  • Yes "filters.assign" can be used to replace the 0 return number and number of return with 1.
    – Hassam Ali
    Commented Aug 8, 2017 at 7:24

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