.PLY file output

Posted by Seck on
URL: http://official-rtab-map-forum.206.s1.nabble.com/PLY-file-output-tp7642.html

Hello,

I have no prior mapping experience but I am using RTAB-Map to create a 3D image of a room. I have exported the cloud as a .ply format. I am then using Python Ply reader (pip install plyfile) to give me an output of the coordinates. It gives the following output:

code/ply code')
ply
format binary_little_endian 1.0
comment PCL generated
element vertex 2188310
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 curvature
element camera 1
property float view_px
property float view_py
property float view_pz
property float x_axisx
property float x_axisy
property float x_axisz
property float y_axisx
property float y_axisy
property float y_axisz
property float z_axisx
property float z_axisy
property float z_axisz
property float focal
property float scalex
property float scaley
property float centerx
property float centery
property int viewportx
property int viewporty
property float k1
property float k2
end_header
[(4.210025 , -3.9631934, -0.38369063, 169, 169, 181, -0.26939332, -0.05563965, -0.96142155, 0.09232759)
 (1.6137965, -7.0459375, -0.34251526,  20,  15,  22, -0.5860401 ,  0.2150358 , -0.7812277 , 0.11243399)
 (4.0508547, -4.6344094, -0.34251526, 122, 119, 128, -0.5842595 ,  0.8115669 ,  0.        , 0.00064412)
 (4.097522 , -4.600813 , -0.34251526, 110, 109, 115, -0.7712584 ,  0.61405885,  0.16760689, 0.11311602)]



My goal is to get the coordinates of the individual points in the point cloud. My problem is I don't understand what the reference frame has been used to measure these points. Is it based on a global reference frame that gets updated when the robot relocalizes? The robot base link? I don't understand the relationship between the robot and the point cloud coordinates.

Also on the PLY data output above, what are the coordinate outputs? Is it (X,Y,Z, R, P, Y, ?, ?, ?, ?)

Thank you for your assistance! If you need any more information, please don't hesitate to ask. I don't know what I don't know at this point and am learning as I go.