[pdal] DSM and DTM mismatch.

[Andrew Bell]

Hi,

We haven't supported the p2g writer since version 1.5.  You should use
writers.gdal instead.  Also, you're reprojection filter is a no-op, as the
input and output SRSs are identical.  If you're wanting to override the SRS
of the input, you can use the "--readers.las.spatialreference" option.

Best,


On Mon, Aug 20, 2018 at 9:09 AM, Murray, Jon <j.murray3 at lancaster.ac.uk>
wrote:

> Ah – apologies. My first post as I explained. As below:
>
>
>
> DSM:
>
>
>
> {
>
>     "pipeline":[
>
>         "input1.las",
>
>
>
>         {
>
>             "type":"filters.reprojection",
>
>             "in_srs":"EPSG:27700",
>
>             "out_srs":"EPSG:27700"
>
>         },
>
>                 {
>
>             "type":"filters.range",
>
>             "limits":"returnnumber[1:1]"
>
>         },
>
>         {
>
>             "type":"writers.p2g",
>
>             "filename":"dsm1",
>
>             "output_type":"idw",
>
>             "output_format":"tif",
>
>             "grid_dist_x":0.5,
>
>             "grid_dist_y":0.5,
>
>             "radius":5
>
>         }
>
>
>
>     ]
>
> }
>
>
>
> DTM
>
> {
>
>     "pipeline":[
>
>          "input1.las",
>
>         {
>
>             "type":"filters.reprojection",
>
>             "in_srs":"EPSG:27700",
>
>             "out_srs":"EPSG:27700"
>
>         },
>
>                 {
>
>             "type":"filters.ground",
>
>             "approximate":true,
>
>             "max_window_size":10,
>
>             "slope":1.0,
>
>             "max_distance":1,
>
>             "initial_distance":0.15,
>
>             "cell_size":1.0,
>
>             "extract":true,
>
>             "classify":false
>
>         },
>
>         {
>
>             "type":"writers.p2g",
>
>             "filename":"dtm1",
>
>             "output_type":"idw",
>
>             "output_format":"tif",
>
>             "grid_dist_x":0.5,
>
>             "grid_dist_y":0.5
>
>         }
>
>     ]
>
> }
>
>
>
> And the CHM:
>
>
>
> gdal_calc.py -A dtm1.idw.tif -B dsm1.idw.tif --calc="B-A" --outfile
> chm1.tif –overwrite
>
>
>
> Regards,
>
>
>
> Jon.
>
>
>
> *From:* Andrew Bell <andrew.bell.ia at gmail.com>
> *Sent:* 20 August 2018 13:58
> *To:* Murray, Jon <j.murray3 at lancaster.ac.uk>
> *Cc:* pdal at lists.osgeo.org
> *Subject:* Re: [pdal] DSM and DTM mismatch.
>
>
>
> You should post pipelines to show how exactly you're creating the files.
>
>
>
> On Mon, Aug 20, 2018 at 8:49 AM, Murray, Jon <j.murray3 at lancaster.ac.uk>
> wrote:
>
> Hello PDAL users,
>
>
>
> This is my first post to you all, having just joined the mailing list, so
> I hope this post is appropriate. I have a problem that I hope there is a
> PDAL (or possibly GDAL) based solution for. I have created both DSM and DTM
> from LiDAR (.las) data, using the appropriate PDAL filters/writers etc. It
> all works well, however there is a slight mismatch in output file sizes.
>
>
>
> The DSM comes out at (3069,1094) and the DTM at (3069,1092), from the same
> input.las file. This prevents the CHM from being created (GDAL side now) as
> of course, the dimensions must match. I have tried reprocessing the DSM/DTM
> and changing grid sizes x/y, but no success.
>
>
>
> Can anyone recommend a solution to this problem please? In short what can
> I do to make the DTM/DSM sizes match?
>
>
>
> Many thanks,
>
>
>
> Jon.
>
>
> _______________________________________________
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>
>
>
>
>
> --
>
> Andrew Bell
> andrew.bell.ia at gmail.com
>



-- 
Andrew Bell
andrew.bell.ia at gmail.com
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