Point Cloud Objects

PcPoint

The basic point cloud type is a PcPoint. Every point has a (large?) number of dimensions, but at a minimum an X and Y coordinate that place it in space.

Points can be rendered in a human-readable JSON form using the PC_AsText(pcpoint) function. The “pcid” is the foreign key reference to the pointcloud_formats table, where the meaning of each dimension in the “pt” array of doubles is explained. The underlying storage of the data might not be double, but by the time it has been extracted, scaled and offset, it is representable as doubles.

{
    "pcid" : 1,
      "pt" : [0.01, 0.02, 0.03, 4]
}

PcPatch

The structure of database storage is such that storing billions of points as individual records in a table is not an efficient use of resources. Instead, we collect a group of PcPoint into a PcPatch. Each patch should hopefully contain points that are near together.

Instead of a table of billions of single PcPoint records, a collection of LIDAR data can be represented in the database as a much smaller collection (10s of millions) of PcPatch records.

Patches can be rendered into a human-readable JSON form using the PC_AsText(pcpatch) function. The “pcid” is the foreign key reference to the pointcloud_formats table.

{
    "pcid" : 1,
     "pts" : [
              [0.02, 0.03, 0.05, 6],
              [0.02, 0.03, 0.05, 8]
             ]
}