[pdal] Z value change on reprojection in pdal 1.6

Michael Smith michael.smith.erdc at gmail.com
Tue Nov 14 07:06:33 PST 2017


Hmm, it might be that pdal is reading the source vertical projection as navd88 and if you are reprojecting and not specifying a vertical projection, it might be assuming wgs84. You can try specifying the output projection as epsg:5070+5703

 

Mike

 

 

-- 

Michael Smith

Remote Sensing/GIS Center

US Army Corps of Engineers

 

 

From: Doug Newcomb <newcomb.ttg at gmail.com>
Date: Tuesday, November 14, 2017 at 9:58 AM
To: Michael Smith <michael.smith.erdc at gmail.com>
Cc: pdal <pdal at lists.osgeo.org>
Subject: Re: [pdal] Z value change on reprojection in pdal 1.6

 

Micheal,

The problem is the z values of all of the point values are have been changed.    I had created a raster from the mean value of the ground points from the pdal reprojected data.  I then went back to NOAA's site and selected a small subset to compare and had their engine deliver the points in Albers Meters Conus   NAVD88.  I imported the points to create a raster in the same way and then subtraced the Z value of the pdal reprojected points from the NOAA reprojected points.  The height values vary by 32-36 m ( see below) .

 

That was why I was asking if I had missed a step that ensured that the Z values stayed at the Geoid12A/12B/NAVD88 values.

 

Tue Nov 14 09:45:55 2017)                                                      

r.info map=noaa_pdal_vert_diff_m at dnewcomb                                       

 +----------------------------------------------------------------------------+

 | Map:      noaa_pdal_vert_diff_m at dnewcom  Date: Tue Nov 14 09:36:19 2017    |

 | Mapset:   dnewcomb                       Login of Creator: dnewcomb        |

 | Location: seva_albers                                                      |

 | DataBase: /data2/grass70_data                                              |

 | Title:    noaa_pdal_vert_diff_m                                            |

 | Timestamp: none                                                            |

 |----------------------------------------------------------------------------|

 |                                                                            |

 |   Type of Map:  raster               Number of Categories: 0               |

 |   Data Type:    FCELL                                                      |

 |   Rows:         12465                                                      |

 |   Columns:      20411                                                      |

 |   Total Cells:  254423115                                                  |

 |        Projection: NAD83 / Conus Albers                                    |

 |            N: 1687158.47979    S: 1668162.01936   Res: 1.52398399          |

 |            E: 1653024.11274    W: 1621917.96408   Res: 1.52398945          |

 |   Range of data:    min = 32.17395  max = 36.06071                         |

 |                                                                            |

 |   Data Description:                                                        |

 |    generated by r.mapcalc                                                  |

 |                                                                            |

 |   Comments:                                                                |

 |    2635_mean_ground_1_524_test_from_noaa_meters at dnewcomb -                 |

 |    2635_mean_ground_1_524 at PERMANENT                                        |

 |                                                                            |

 +----------------------------------------------------------------------------+

 

 

 

Doug

 

On Mon, Nov 13, 2017 at 8:20 PM, Michael Smith <michael.smith.erdc at gmail.com> wrote:

Doug,

 

It looks like perhaps the header metadata is not correct, which is what I think you are seeing from lasinfo. When you inspected the Decimal Degrees file it shows

 

        "bbox":

        {

          "maxx": -76.2527221,

          "maxy": 37.9068695,

          "maxz": -5.777103023,

          "minx": -76.2571767,

          "miny": 37.9028129,

          "minz": -35.71281856

        },

 

which match your albers output. 

 

 

-- 

Michael Smith

Remote Sensing/GIS Center

US Army Corps of Engineers

 

 

From: pdal <pdal-bounces at lists.osgeo.org> on behalf of Doug Newcomb <newcomb.ttg at gmail.com>
Date: Monday, November 13, 2017 at 8:14 PM
To: pdal <pdal at lists.osgeo.org>
Subject: [pdal] Z value change on reprojection in pdal 1.6

 

Ok,

Finally diving into pdal more deeply.  I installed the docker  instance of pdal 1.6 and tried a bit of command line reprojection:

 

I downloaded some data from the NOAA website and  re-projected from Decimal Degrees to Albers Meters Conus ( EPSG:5070) 

pdal translate /data/20100503_LAS_S23_1836_10.laz /data/albers_20100503_LAS_S23_1836_10.laz -f filters.reprojection  --filters.reprojection.out_srs="EPSG:5070"

 

 For the input data , lasinfo gives :

 

 

  Minimum and Maximum Attributes (min,max)

---------------------------------------------------------

  Min X, Y, Z:                         -76.2571767, 37.9028129, 0.024

  Max X, Y, Z:                        -76.2527221, 37.9068695, 29.966

  Bounding Box:                   -76.2571767, 37.9028129, -76.2527221, 37.9068695

 

for the output laz file, lasinfo gives:

 

  Minimum and Maximum Attributes (min,max)

---------------------------------------------------------

  Min X, Y, Z:                         1707096.44, 1829911.69, -35.72

  Max X, Y, Z:                        1707557.20, 1830350.12, -5.77

  Bounding Box:                   1707096.44, 1829911.69, 1707557.20, 1830350.12

 

 

pdal info for the input file gives:

 

 

{

  "filename": "\/data\/20100503_LAS_S23_1836_10.laz",

  "pdal_version": "1.6.0 (git-version: 94ad83)",

  "stats":

  {

    "bbox":

    {

      "EPSG:4326":

      {

        "bbox":

        {

          "maxx": -76.2527221,

          "maxy": 37.9068695,

          "maxz": -5.777103023,

          "minx": -76.2571767,

          "miny": 37.9028129,

          "minz": -35.71281856

        },

        "boundary": {

   "coordinates" : [

      [

         [ -76.257176700000002, 37.902812900000001 ],

         [ -76.257176700000002, 37.906869499999999 ],

         [ -76.2527221, 37.906869499999999 ],

         [ -76.2527221, 37.902812900000001 ],

         [ -76.257176700000002, 37.902812900000001 ]

      ]

   ],

   "type" : "Polygon"

}

 

      },

      "native":

      {

        "bbox":

        {

          "maxx": -76.2527221,

          "maxy": 37.9068695,

          "maxz": 29.966,

          "minx": -76.2571767,

          "miny": 37.9028129,

          "minz": 0.024

        },

        "boundary": {

 

pdal info on the output laz file gives:

{

  "filename": "\/data\/albers_20100503_LAS_S23_1836_10.laz",

  "pdal_version": "1.6.0 (git-version: 94ad83)",

  "stats":

  {

    "bbox":

    {

      "EPSG:4326":

      {

        "bbox":

        {

          "maxx": -76.25185156,

          "maxy": 37.90686951,

          "maxz": -5.77,

          "minx": -76.25806657,

          "miny": 37.9021939,

          "minz": -35.72

        },

        "boundary": {

   "coordinates" : [

      [

         [ -76.258066569999997, 37.903041880000004 ],

         [ -76.257028300000002, 37.90686951 ],

         [ -76.251851560000006, 37.90602148 ],

         [ -76.252890100000002, 37.9021939 ],

         [ -76.258066569999997, 37.903041880000004 ]

      ]

   ],

   "type" : "Polygon"

}

 

      },

      "native":

      {

        "bbox":

        {

          "maxx": 1707557.2,

          "maxy": 1830350.12,

          "maxz": -5.77,

          "minx": 1707096.44,

          "miny": 1829911.69,

          "minz": -35.72

        },

        "boundary": {

 

 

Am I missing a switch in the translate command?

 

 

Doug

 

 

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