vo_practice

visual odometry practice The frame is from gaoxiang's slam book. Many techniques in ORB-SLAM2 are transplanted here, like ORB features and matching, local mapping and 4 steps optimization, covisibility graph.

Flow

state=initilize  
for a new frame:
  detect features and compute features description
  if state==initilize:
    compute the depth by stereo and add the points to map.mappoints
    state = OK
  else:
    match features with previous frame
    estimate the pose by PnP
    find more matches by projection
    estimate the pose by PnP
    if pose estimation is accepted:
      if need key frame:
        insert new points to map.mpapoints
        insert current frame to map.keyframes
        update connection(i.e. covisibility)
        fuse map.mappoints,(i.e. merge close mappoints)
        local bundle adjustment for current keyframe
    else://tracking fails, re-init
      estimate the pose by motion
      add the points to map.mappoints

Result

We use several sequences from KITTI dataset to show the result.

The evaluation tool is from TUM tools.

The following table shows the ATE and RPE result on three sequence,including 03, 04 and 07.

sequence id	03	04	07
duration (s)	82.72	28.11	114.33
rmse (m)	1.47	0.46	3.43
mean (m)	1.35	0.43	3.11
midian (m)	1.26	0.38	2.91
std (m)	0.58	0.16	1.45
min (m)	0.38	0.14	0.58
max (m)	4.40	1.22	6.04
RPE	0.57	0.31	0.54

The following figure shows the trajectory comparison of sequence 07.