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The issue:

I have a a PLY point cloud file computed from a photogrammetric acquisition that has been processed in CloudCompare.

The header look like:

ply
format binary_little_endian 1.0
comment Created by CloudCompare v2.10-alpha
comment Created 24.08.18 17:12
obj_info Generated by CloudCompare!
element vertex 2162869
property float x
property float y
property float z
property uchar red
property uchar green
property uchar blue
property float nx
property float ny
property float nz
property float scalar_C2C_absolute_distances[2D1/2_Triangulation][k=6]_(X)
property float scalar_C2C_absolute_distances[2D1/2_Triangulation][k=6]_(Y)
property float scalar_C2C_absolute_distances[2D1/2_Triangulation][k=6]
property float scalar_Temp._approx._distances
property float scalar_Approx._distances
property float scalar_C2C_absolute_distances[2D1/2_Triangulation][k=6]_(Z)
end_header

One can see some extra scalar fields in addition to the standard XYZ, RGB and normals values. These extra fields are useful to colorize the cloud in CloudCompare based on some analysis, here for example the distance from a reference cloud.

I would like to display such cloud on a web page. All tools I met, for example Potree tiles, or Cesium 3D Tiles are using 3D tiles in LAS or LAZ format.

But the LAS ASPRS specification only allows for predefined and strictly constrained fields, which is a good thing. Naturally, most of these fields do not exist when the point cloud is not acquired by a LIDAR.
And I just didn't find some extra empty fields for any user-defined values.

The question:

Do you know a way to keep the scalar field values from the PLY file up to the display of 3D tiles in a web browser so that they can be used to colorize the cloud in the web page?

Edit:

As sugested: I cannot convert the PLY file with PotreeConverter directly, the output is buggy, I end up with inf coordinates so I have to convert the PLY file to a LAS file before using PotreeConverter. This is where I lose the scalar field informations because the LAS file format is standardized and doesn't accept other fields.

  • Keep monitoring iTowns. They have a plan to add support for PLY data format. See github.com/iTowns/itowns/wiki/Supported-Features. – Andre Silva Sep 3 '18 at 15:44
  • What happens when you convert the PLY file to Potree file format? See github.com/potree/potree/issues/147. – Andre Silva Sep 8 '18 at 13:05
  • I cannot convert the PLY file with PotreeConverter directly, the output is buggy, I end up with inf coordinates so I have to convert the PLY file to a LAS file before using PotreeConverter. This is where I lose the scalar field informations because the LAS file format is standardized and doesn't accept other fields. – s.k Sep 10 '18 at 6:15
  • I suggest you edit your question to include this piece of information. Let me know of you decide to edit it (ping me with @AndreSilva). Tks. – Andre Silva Sep 10 '18 at 12:42

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