verma/plasio

Dataset is displayed as a long stacked line of points

pierotofy opened this issue · 3 comments

pierotofy commented

Hello,

I was wondering if somebody could help me understand why some data is not displaying properly on plas.io, I'm thinking it's probably something funky with the dataset, but I just can't figure out what, or how to fix it.

I downloaded some datasets from coast.noaa.gov: https://coast.noaa.gov/htdata/lidar1_z/geoid12a/data/2507/

Taking as an example the first two files from the list of Point Cloud Data Files:

When I load them to plas.io I get a long line of points:

image

Other things I noticed:

  • If I perform a pdal translate 20090825_pt000542.laz uncompressed.las and load uncompressed.las into http://lidarview.com I get the same long line.
  • If I perform a laszip -i 20090825_pt000542.laz -o uncompressed2.las using LASTools and load uncompressed2.las into http://lidarview.com I get:

image

PDAL returns the following with the info summary command:

root@7bca0abdf4b6:/lidar# pdal info --summary 20090825_pt000541.laz 
{
  "filename": "20090825_pt000541.laz",
  "pdal_version": "1.4.0 (git-version: c7cef9)",
  "summary":
  {
    "bounds":
    {
      "X":
      {
        "max": -90.96873434,
        "min": -90.97300214
      },
      "Y":
      {
        "max": 46.6097259,
        "min": 46.6022752
      },
      "Z":
      {
        "max": 244.868,
        "min": 195.739
      }
    },
    "dimensions": "X, Y, Z, Intensity, ReturnNumber, NumberOfReturns, ScanDirectionFlag, EdgeOfFlightLine, Classification, ScanAngleRank, UserData, PointSourceId, GpsTime",
    "num_points": 123644,
    "srs":
    {
      "compoundwkt": "COMPD_CS[\"unknown\",GEOGCS[\"NAD83\",DATUM[\"North_American_Datum_1983\",SPHEROID[\"GRS 1980\",6378137,298.2572221010002,AUTHORITY[\"EPSG\",\"7019\"]],AUTHORITY[\"EPSG\",\"6269\"]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433],AUTHORITY[\"EPSG\",\"4269\"]],VERT_CS[\"NAVD88 height\",VERT_DATUM[\"North American Vertical Datum 1988\",2005,AUTHORITY[\"EPSG\",\"5103\"],EXTENSION[\"PROJ4_GRIDS\",\"g2012a_conus.gtx,g2012a_alaska.gtx,g2012a_guam.gtx,g2012a_hawaii.gtx,g2012a_puertorico.gtx,g2012a_samoa.gtx\"]],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],AXIS[\"Up\",UP],AUTHORITY[\"EPSG\",\"5703\"]]]",
      "horizontal": "GEOGCS[\"NAD83\",DATUM[\"North_American_Datum_1983\",SPHEROID[\"GRS 1980\",6378137,298.2572221010002,AUTHORITY[\"EPSG\",\"7019\"]],AUTHORITY[\"EPSG\",\"6269\"]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433],AUTHORITY[\"EPSG\",\"4269\"]]",
      "isgeocentric": false,
      "isgeographic": true,
      "prettycompoundwkt": "COMPD_CS[\"unknown\",    GEOGCS[\"NAD83\",        DATUM[\"North_American_Datum_1983\",            SPHEROID[\"GRS 1980\",6378137,298.2572221010002,                AUTHORITY[\"EPSG\",\"7019\"]],            AUTHORITY[\"EPSG\",\"6269\"]],        PRIMEM[\"Greenwich\",0],        UNIT[\"degree\",0.0174532925199433],        AUTHORITY[\"EPSG\",\"4269\"]],    VERT_CS[\"NAVD88 height\",        VERT_DATUM[\"North American Vertical Datum 1988\",2005,            AUTHORITY[\"EPSG\",\"5103\"],            EXTENSION[\"PROJ4_GRIDS\",\"g2012a_conus.gtx,g2012a_alaska.gtx,g2012a_guam.gtx,g2012a_hawaii.gtx,g2012a_puertorico.gtx,g2012a_samoa.gtx\"]],        UNIT[\"metre\",1,            AUTHORITY[\"EPSG\",\"9001\"]],        AXIS[\"Up\",UP],        AUTHORITY[\"EPSG\",\"5703\"]]]",
      "prettywkt": "GEOGCS[\"NAD83\",    DATUM[\"North_American_Datum_1983\",        SPHEROID[\"GRS 1980\",6378137,298.2572221010002,            AUTHORITY[\"EPSG\",\"7019\"]],        AUTHORITY[\"EPSG\",\"6269\"]],    PRIMEM[\"Greenwich\",0],    UNIT[\"degree\",0.0174532925199433],    AUTHORITY[\"EPSG\",\"4269\"]]",
      "proj4": "+proj=longlat +datum=NAD83 +geoidgrids=g2012a_conus.gtx,g2012a_alaska.gtx,g2012a_guam.gtx,g2012a_hawaii.gtx,g2012a_puertorico.gtx,g2012a_samoa.gtx +vunits=m +no_defs",
      "units":
      {
        "horizontal": "metre",
        "vertical": "metre"
      },
      "vertical": "VERT_CS[\"NAVD88 height\",VERT_DATUM[\"North American Vertical Datum 1988\",2005,AUTHORITY[\"EPSG\",\"5103\"],EXTENSION[\"PROJ4_GRIDS\",\"g2012a_conus.gtx,g2012a_alaska.gtx,g2012a_guam.gtx,g2012a_hawaii.gtx,g2012a_puertorico.gtx,g2012a_samoa.gtx\"]],UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]],AXIS[\"Up\",UP],AUTHORITY[\"EPSG\",\"5703\"]]",
      "wkt": "GEOGCS[\"NAD83\",DATUM[\"North_American_Datum_1983\",SPHEROID[\"GRS 1980\",6378137,298.2572221010002,AUTHORITY[\"EPSG\",\"7019\"]],AUTHORITY[\"EPSG\",\"6269\"]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433],AUTHORITY[\"EPSG\",\"4269\"]]"
    }
  }
}

If this is not the right place to ask this question, please let me know. Thank you!

m-schuetz commented 
"X": {
  "max": -90.96873434,
  "min": -90.97300214
},"Y":{
  "max": 46.6097259,
  "min": 46.6022752
},"Z":{
  "max": 244.868,
  "min": 195.739
}

The extremely small range of your x and y coordinates compared to the range of your z coordinates indicates that x and y are likely in lat/long/angles and only the z coordinate is in meters. I don't know how exactly but if you can transform the data set so that all your coordinates are in meters, you'll get the expected result.

lidar532 commented
pierotofy commented

Thank you both! Once converted to UTM the data displayed properly (which makes sense, since UTM usually uses meters for its planar coordinates).

Cheers!

image