[pdal] Way to cast dimension data type?

[Andrew Bell]

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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