Extract Depth From Depth Image

amiranda

I have a pmd tof sensor and I am able to see its imagery using voxl-portal or rosrun image_view but how can I extract the depth of the points in mm? Is there an easy way to do that while I do some testing or do I have to write something up to subscribe and print the various points out?

Is there a handy logging tool of somesort that could give me an array of depth points?

Thanks

Hi,

We have a feature in the works for our voxl-logger project that would allow it to log tof data to a file. In the meantime, you can use voxl-inspect-points to look at a subsample of the points, or copy and modify the source to process the data however you'd like.

amiranda

Thanks @Alex-Gardner ,

If I enter voxl-inspect-points tof_pc -n then is the z axis supposed to be depth in mm? Is there a scale that is supposed to be applied to get between float and distance?

Also is something like the following the expected output? It just says Float XYZ.
timestamp(ms)| # points | # bytes | Format
8104565 | 38528 | 462336 | Float XYZ
8104628 | 38528 | 462336 | Float XYZ
8104696 | 38528 | 462336 | Float XYZ
8104758 | 38528 | 462336 | Float XYZ

I can start going through the source, I just want to make sure I understand everything so I can get the correct depth in distance extracted.

Thanks for your help.

Hey @amiranda,

For the tof points, each axis is measured in meters, no scaling is needed.

amiranda

Okay, in the meantime, I ended up creating a subscriber for the tof_pc and I managed to extract the x,y and z points. Im assuming that the z point that I extracted from the voxl_mpa_to_ros is the same as the one used in voxl-inspect-points, so that z axis is also reported in meters correct?

Thanks for you help so far.