Why is pcread not reading the colour in a .PLY file?

I would like to import a densified point cloud I constructed in Pix4D into MATLAB. I had exported the point cloud from Pix4D as a .PLY file, ticking the option to save colours. When I uploaded my point cloud on sketchfab.com, thecolours were present, so the .PLY file clearly contains the colour information. But when I used pcread to read the point cloud into MATLAB, the resulting pointCloud object did not have any colour information, only x,y,z points.

I have tried to see if colour needs to be imported separately, but I cannot find out how to do this, and it would appear that colour should have been imported alongside the xyz points with pcread.

If anyone has any advice, I would be very thankful. Pix4D cannot save as .PCD so I need to use .PLY if possible.

Thanks!

[Nirav Sharda]

Can you attach the .ply file? I tried to use 'pcread' on a file downloaded from http://www.kscan3d.com/gallery/ and it seem to work fine. It gives me the color information. The version of MATLAB I used was R2016a.

[David Pritchard]

Hi Nirav, I am also using R2016a.

The zipped file is still more than 5MB, so I am afraid I cannot attach it here, but I have put the model on Sketchfab at this link: https://skfb.ly/6pKY6

You should be able to download the .ply file from there.

Answer 1

[David Pritchard]

A friend of mine has just found a solution to this, which I will add in case anyone else encounters this problem.

If I open the .PLY file from Pix4D in notepad the colours are called e.g. "property uchar diffuse_red", which different to what pcread is expecting.

By changing the colour names to e.g. "property uchar red" and saving the .PLY file, pcread was able to read the point cloud with correct colours.

[Raymond Phan]

Thanks for this. This was my problem as well. I was originally using diffuse_red and have removed it from my ply file. Thanks again!

[Loki Scarlette]

Thank you so much

Answer 2

[Charles Han]

Hi, i am on the same situation using pix4d export the .ply file and the head code of the file is binary_little_endian. But in my matlab program, the pcread cant read the binary file but it can read the ascii head file. I am wondering how you nake it.