[pdal] Way to cast dimension data type?

[Piero Toffanin]

Wow, thanks for looking into this so quickly!

-Piero


On 05/08/2017 10:17 AM, Howard Butler wrote:
> I pushed the tag to trigger the pdal/pdal:latest docker image rebuild if you want to verify using that mechanism. Otherwise, you will have to build master yourself to confirm.
>
> Thanks for the report Piero!
>
> Howard
>
>> On May 8, 2017, at 8:59 AM, Andrew Bell <andrew.bell.ia at gmail.com> wrote:
>>
>> I opened this ticket:
>>
>> https://github.com/PDAL/PDAL/issues/1584
>>
>> It should be fixed shortly.
>>
>> On Sat, May 6, 2017 at 5:36 PM, Piero Toffanin <pt at masseranolabs.com> wrote:
>> Hello,
>>
>> First let me say that PDAL rocks. I love it.
>> I was wondering if there's a way to specify (cast) the data type of the X,Y,Z dimensions while reading a PLY file (so in effect override the type specified in the PLY header) in the PDAL pipeline.
>>
>> I have an input PLY file (untransformed.ply) that has the header:
>>
>> ply
>> format ascii 1.0
>> [ .... ]
>> property float x
>> property float y
>> property float z
>> [ .... ]
>>
>> And coordinate points with ~5 digits of precision.
>>
>> 1.13759 12.1322 162.786
>> [ .... ]
>> When I try to apply the following transform (add a east/north offset):
>> {
>>    "pipeline": [
>>      "untransformed.ply",
>>      {
>>        "matrix": "1 0 0 576705 0 1 0 5188170 0 0 1 0 0 0 0 1",
>>        "type": "filters.transformation"
>>      },
>>      {
>>        "a_srs": "EPSG:32615",
>>        "filename": "transformed.las",
>>        "offset_x": "576705",
>>        "offset_y": "5188170",
>>        "offset_z": "0"
>>      }
>>    ]
>> }
>> There's a loss of precision (I get a "grid-like" output, see https://cloud.githubusercontent.com/assets/1951843/25507885/9cd01d12-2b7c-11e7-9c54-0e219dae4f05.png). I think it's because the matrix transformation code here https://github.com/PDAL/PDAL/blob/dd97a033c5d487000e200304a7619e9978de6ae2/filters/TransformationFilter.cpp#L106 correctly treats points as floats.
>> Changing the PLY header to:
>>
>> ply
>> format ascii 1.0
>> [ .... ]
>> property double x
>> property double y
>> property double z
>> [ .... ]
>>
>> Produces the expected output (no grid-like output).
>> I was wondering if I could force the dimensions to be treated as a double directly from PDAL? Or perhaps is there interest in adding a flag (cast to dimension) in PDAL's PLY reader (I'd be happy to contribute to it)?
>> More information about the background of this issue is also available here: https://github.com/OpenDroneMap/OpenDroneMap/issues/522
>>
>> Thank you for any information you might have!
>>
>> -Piero
>>
>>
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>>
>>
>> -- 
>> Andrew Bell
>> andrew.bell.ia at gmail.com
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