Install libopencv on Starling 2

wilkinsaf

@Judoor-0 Gotcha. Let me know if this doesnt answer your question.

you can use voxl mpa to ros2: https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-mpa-to-ros2
and this will allow you to access camera frame information

Judoor 0

@wilkinsaf Does mpa to ros do the same thing? Because I currently use ROS1. And for ROS1, mpa to ros only sends camera images or point cloud, not camera_infos.

Prabhav Gupta

@Judoor-0 @wilkinsaf

I am working on something very similar as well and am facing the same issue.

I need to run RTAB-MAP for SLAM using the drone's sensors (Video and IMU). But RTAB-MAP expects camera_info (the camera matrix and other variables, as explained by @Judoor-0 above) along with video data.

One way to provide this information to RTAB-MAP is by creating a seperate publisher and publish this data over a ROS topic as done in one of the posts above. But I suspect it would be better if the voxl-mpa-to-ros package could provide the exact camera matrix and other variables (as specified here - https://docs.ros.org/en/noetic/api/sensor_msgs/html/msg/CameraInfo.html) as a ROS topic directly.

Kindly let us know if there is any way to implement this.

@Judoor-0, were you able to run SLAM using the stereo data from the drone? Or did you use depth data from a depth camera? The RB5 flight drone that I am using does not provide depth data directly, and hence I was thinking of using the Stereo data package within RTAB-MAP.

Thanks!

Alex Kushleyev

@Prabhav-Gupta,

The easiest way to do this, perhaps, is to create a python script that reads the camera calibration json and publishes a latched message via rospy. Similarly it could be done in C++ with a little more effort.. I don't think this currently exists.

Alex

Prabhav Gupta

@Alex-Kushleyev

Yes, that is similar to what I had in mind. I will try this out.

Thanks!

Judoor 0

@Prabhav-Gupta I didn't use the stereo data because I don't have one on my drone. I used the point cloud returned by the TOF. But I know that with RTAB-Map you can easily use stereo without depth. There are some examples that may help you in the rtabmap_ros website.

Prabhav Gupta

@Judoor-0 Thanks a lot, I will look into it.

Prabhav Gupta

@Alex-Kushleyev

I was trying to create this script -

@Alex-Kushleyev said in Install libopencv on Starling 2:

The easiest way to do this, perhaps, is to create a python script that reads the camera calibration json and publishes a latched message via rospy. Similarly it could be done in C++ with a little more effort.. I don't think this currently exists.

and need some help.

I am working with the RB5 drone and found this in the /data/modalai/ folder in the drone:

In opencv_stereo_front_extrinsics.yml:

rb5:/data/modalai$ cat opencv_stereo_front_extrinsics.yml                                                                                                                                                            
%YAML:1.0                                                                                                                                                                                                            
---                                                                                                                                                                                                                  
R: !!opencv-matrix                                                                                                                                                                                                   
   rows: 3                                                                                                                                                                                                           
   cols: 3                                                                                                                                                                                                           
   dt: d                                                                                                                                                                                                             
   data: [ 9.9995382093423246e-01, -9.1903872613942166e-03,
       -2.8094093711296423e-03, 9.2509466314868449e-03,
       9.9970714036476482e-01, 2.2361875818584419e-02,
       2.6030723098620125e-03, -2.2386832864208624e-02,
       9.9974599460505953e-01 ]
T: !!opencv-matrix
   rows: 3
   cols: 1
   dt: d
   data: [ -7.9639069991921108e-02, -9.0666624431155548e-05,
       -1.0799460870486485e-03 ]
reprojection_error: 2.7322523335815047e-01
calibration_time: "2022-04-08 23:15:23"

and in opencv_stereo_front_intrinsics.yml:

rb5:/data/modalai$ cat opencv_stereo_front_intrinsics.yml
%YAML:1.0
---
M1: !!opencv-matrix
   rows: 3
   cols: 3
   dt: d
   data: [ 5.0159907997903338e+02, 0., 2.9377341710319376e+02, 0.,
       5.0083699409439379e+02, 2.3544444409742863e+02, 0., 0., 1. ]
D1: !!opencv-matrix
   rows: 5
   cols: 1
   dt: d
   data: [ -1.6571748643440132e-01, 6.3134583515870882e-02,
       2.4908601395800438e-03, 6.9258577723375913e-04, 0. ]
reprojection_error1: 1.8877343672847582e-01
M2: !!opencv-matrix
   rows: 3
   cols: 3
   dt: d
   data: [ 5.0289492433892644e+02, 0., 3.1156572782508289e+02, 0.,
       5.0234014337071841e+02, 2.4962793784523797e+02, 0., 0., 1. ]
D2: !!opencv-matrix
   rows: 5
   cols: 1
   dt: d
   data: [ -1.6640627389329365e-01, 6.4800083011513396e-02,
       1.1988146735987267e-04, -6.3680006718804514e-04, 0. ]
reprojection_error2: 1.8906708149286014e-01
width: 640
height: 480
distortion_model: plumb_bob
calibration_time: "2022-04-08 23:15:23"

To create the script that publishes CameraInfo, I need to figure out the information within these two files that correspond to the variables within the CameraInfo class as given here: https://docs.ros.org/en/noetic/api/sensor_msgs/html/msg/CameraInfo.html

sensor_msgs/CameraInfo:

std_msgs/Header header
uint32 height
uint32 width
string distortion_model
float64[] D
float64[9] K
float64[9] R
float64[12] P
uint32 binning_x
uint32 binning_y
sensor_msgs/RegionOfInterest roi

Some of the variable mappings are clear, such as height, width, distortion model, R and D.

How do I map K and P required by CameraInfo from the Calibration files? And anything else that I should potentially look out for while doing this mapping?

Thanks!

Alex Kushleyev

@Prabhav-Gupta ,

K is your M1 and M2 matrices for both cameras (3x3 Intrinsic camera matrix)

The link you shared has information how to compute the P matrix. I am not sure if it would be used by your application though.

Alex

Prabhav Gupta

@Alex-Kushleyev,

Cool, Thanks a lot!