What is the osm-bundler *.ply camera position format? - openstreetmap

Question

I'm trying out the OpenStreetMap bundler program and I can't find details on the camera position data. The point cloud data is in a *.ply file that looks like this:
ply
format ascii 1.0
element face 0
property list uchar int vertex_indices
element vertex 1340
property float x
property float y
property float z
property uchar diffuse_red
property uchar diffuse_green
property uchar diffuse_blue
end_header
-1.967914e-001 -8.918888e-001 -3.318706e+000 92 86 88
-1.745216e-001 -2.186521e-001 -3.227759e+000 50 33 31
-1.585826e-001 -1.894233e-001 -3.271651e+000 61 43 43
...
-2.649703e-003 2.197792e-002 3.906710e-002 0 255 0
-2.354721e-003 2.235805e-002 -1.093058e-002 255 255 0
5.296331e-003 4.755635e-001 -1.298959e+000 255 0 0
3.155302e-003 4.634443e-001 -1.347420e+000 255 255 0
1.910245e-003 2.891324e-001 -1.070228e-001 0 255 0
2.508708e-003 2.884968e-001 -1.570152e-001 255 255 0
-2.246127e-002 -6.257610e-001 9.884196e-001 255 0 0
-2.333330e-002 -6.187732e-001 9.389180e-001 255 255 0
The last eight lines appear to be the positions for four cameras (from four images). One line is position, second line is orientation. The position colors are either green or red and the orientation is yellow.
I can't find info on this so I'm wondering if this is correct and also what does red and green mean? Good/bad data? Any other info about using osm-bundler results is helpful.

Answer 1

I'm also looking at how to get the camera position data from Bundler (note I'm not using osm-bundler but the original program). However, as well as outputting the PLY file bundler also outputs an ASCII file called bundle.out. This contains parameters that allow you to calculate the camera positions, as described in the bundler documentation.

Answer 2

Bundler incrementally solves for the camera positions/poses and outputs the final answer in the bundler.out file. The .ply file contains point cloud vertices, faces, and RGB color information. The .ply file does not contain the camera poses. You can find information about the bundler.out file here. ( osm-bundler uses the Noah Slavely's bundler program, so this answer applies to both of your questions )
http://www.cs.cornell.edu/~snavely/bundler/bundler-v0.4-manual.html#S6
So, you look at the first number in the second row to determine the number of cameras. The next number tells you the number of points which follow the cameras. Each camera entry consists of five rows.
<f> <k1> <k2> row one
<R> rows two, three, and four
<t> row five
So, lines one and two give you header information. Then each group of five rows is a seperate camera entry starting with camera number zero. If rows contain zero, then their is no data for that camera/image.
If the first two rows bundle.out contain
#Bundle file v0.3
16 32675
There will be 16 cameras and 32675 points. The camera information will be on lines
3 through (16*5 + 2). In vi or emacs you can display line numbers to help you examine the file. ( In vi, :set numbers on ) Remember that the rotation matrix is three lines of three numbers and the translation three vector is the fith and last line of a camera definition.
The points follow the camera definitions. You can find information about the format of points at the link I provided above.