def track_previous_frame(self, f_ref, f_cur):
print('>>>> tracking previous frame ...')
is_search_frame_by_projection_failure = False
use_search_frame_by_projection = self.motion_model.is_ok and kUseSearchFrameByProjection and kUseMotionModel
if use_search_frame_by_projection:
# search frame by projection: match map points observed in f_ref with keypoints of f_cur
print('search frame by projection')
search_radius = Parameters.kMaxReprojectionDistanceFrame
f_cur.reset_points()
self.timer_seach_frame_proj.start()
idxs_ref, idxs_cur, num_found_map_pts = search_frame_by_projection(
f_ref,
f_cur,
max_reproj_distance=search_radius,
max_descriptor_distance=self.descriptor_distance_sigma)
self.timer_seach_frame_proj.refresh()
self.num_matched_kps = len(idxs_cur)
print("# matched map points in prev frame: %d " %
self.num_matched_kps)
# if not enough map point matches consider a larger search radius
if self.num_matched_kps < Parameters.kMinNumMatchedFeaturesSearchFrameByProjection:
f_cur.remove_frame_views(idxs_cur)
f_cur.reset_points()
idxs_ref, idxs_cur, num_found_map_pts = search_frame_by_projection(
f_ref,
f_cur,
max_reproj_distance=2 * search_radius,
max_descriptor_distance=0.5 *
self.descriptor_distance_sigma)
self.num_matched_kps = len(idxs_cur)
Printer.orange(
"# matched map points in prev frame (wider search): %d " %
self.num_matched_kps)
if kDebugDrawMatches and True:
img_matches = draw_feature_matches(f_ref.img,
f_cur.img,
f_ref.kps[idxs_ref],
f_cur.kps[idxs_cur],
f_ref.sizes[idxs_ref],
f_cur.sizes[idxs_cur],
horizontal=False)
cv2.imshow('tracking frame by projection - matches',
img_matches)
cv2.waitKey(1)
if self.num_matched_kps < Parameters.kMinNumMatchedFeaturesSearchFrameByProjection:
f_cur.remove_frame_views(idxs_cur)
f_cur.reset_points()
is_search_frame_by_projection_failure = True
Printer.red(
'Not enough matches in search frame by projection: ',
self.num_matched_kps)
else:
# search frame by projection was successful
if kUseDynamicDesDistanceTh:
self.descriptor_distance_sigma = self.dyn_config.update_descriptor_stat(
f_ref, f_cur, idxs_ref, idxs_cur)
# store tracking info (for possible reuse)
self.idxs_ref = idxs_ref
self.idxs_cur = idxs_cur
# f_cur pose optimization 1:
# here, we use f_cur pose as first guess and exploit the matched map point of f_ref
self.pose_optimization(f_cur, 'proj-frame-frame')
# update matched map points; discard outliers detected in last pose optimization
num_matched_points = f_cur.clean_outlier_map_points()
print(' # num_matched_map_points: %d' %
(self.num_matched_map_points))
#print(' # matched points: %d' % (num_matched_points) )
if not self.pose_is_ok or self.num_matched_map_points < kNumMinInliersPoseOptimizationTrackFrame:
Printer.red(
'failure in tracking previous frame, # matched map points: ',
self.num_matched_map_points)
self.pose_is_ok = False
if not use_search_frame_by_projection or is_search_frame_by_projection_failure:
self.track_reference_frame(f_ref, f_cur, 'match-frame-frame')
def track(self, img, frame_id, pose=None, verts=None):
# check image size is coherent with camera params
print("img.shape ", img.shape)
print("cam ", self.H, " x ", self.W)
assert img.shape[0:2] == (self.H, self.W)
self.timer_main_track.start()
# build current frame
self.timer_frame.start()
f_cur = Frame(self.map, img, self.K, self.Kinv, self.D, des=verts)
self.timer_frame.refresh()
if self.stage == SLAMStage.NO_IMAGES_YET:
# push first frame in the inizializer
self.intializer.init(f_cur)
self.stage = SLAMStage.NOT_INITIALIZED
return # EXIT (jump to second frame)
if self.stage == SLAMStage.NOT_INITIALIZED:
# try to inizialize
initializer_output, is_ok = self.intializer.initialize(f_cur, img)
if is_ok:
f_ref = self.intializer.f_ref
# add the two initialized frames in the map
self.map.add_frame(
f_ref) # add first frame in map and update its id
self.map.add_frame(
f_cur) # add second frame in map and update its id
# add points in map
new_pts_count, _ = self.map.add_points(
initializer_output.points4d, None, f_cur, f_ref,
initializer_output.idx_cur, initializer_output.idx_ref,
img)
Printer.green("map: initialized %d new points" %
(new_pts_count))
self.stage = SLAMStage.OK
return # EXIT (jump to next frame)
f_ref = self.map.frames[-1] # get previous frame in map
self.map.add_frame(f_cur) # add f_cur to map
# udpdate (velocity) motion model (kinematic without damping)
self.velocity = np.dot(f_ref.pose,
np.linalg.inv(self.map.frames[-2].pose))
predicted_pose = np.dot(self.velocity, f_ref.pose)
if kUseMotionModel is True:
print('using motion model')
# set intial guess for current pose optimization
f_cur.pose = predicted_pose.copy()
#f_cur.pose = f_ref.pose.copy() # get the last pose as an initial guess for optimization
if kUseSearchFrameByProjection:
# search frame by projection: match map points observed in f_ref with keypoints of f_cur
print('search frame by projection...')
idx_ref, idx_cur, num_found_map_pts = search_frame_by_projection(
f_ref, f_cur)
print("# found map points in prev frame: %d " %
num_found_map_pts)
else:
self.timer_match.start()
# find keypoint matches between f_cur and f_ref
idx_cur, idx_ref = match_frames(f_cur, f_ref)
self.num_matched_kps = idx_cur.shape[0]
print('# keypoint matches: ', self.num_matched_kps)
self.timer_match.refresh()
else:
print('estimating pose by fitting essential mat')
self.timer_match.start()
# find keypoint matches between f_cur and f_ref
idx_cur, idx_ref = match_frames(f_cur, f_ref)
self.num_matched_kps = idx_cur.shape[0]
print('# keypoint matches: ', self.num_matched_kps)
self.timer_match.refresh()
# N.B.: please, in order to understand the limitations of fitting an essential mat, read the comments of the method self.estimate_pose_ess_mat()
self.timer_pose_est.start()
# estimate inter frame camera motion by using found keypoint matches
Mrc = self.estimate_pose_ess_mat(f_ref.kpsn[idx_ref],
f_cur.kpsn[idx_cur])
Mcr = np.linalg.inv(poseRt(Mrc[:3, :3], Mrc[:3, 3]))
f_cur.pose = np.dot(Mcr, f_ref.pose)
self.timer_pose_est.refresh()
# remove outliers from keypoint matches by using the mask computed with inter frame pose estimation
mask_index = (self.mask_match.ravel() == 1)
self.num_inliers = sum(mask_index)
print('# inliers: ', self.num_inliers)
idx_ref = idx_ref[mask_index]
idx_cur = idx_cur[mask_index]
# if too many outliers reset estimated pose
if self.num_inliers < kNumMinInliersEssentialMat:
f_cur.pose = f_ref.pose.copy(
) # reset estimated pose to previous frame
Printer.red('Essential mat: not enough inliers!')
# set intial guess for current pose optimization:
# keep the estimated rotation and override translation with ref frame translation (we do not have a proper scale for the translation)
f_cur.pose[:, 3] = f_ref.pose[:, 3].copy()
#f_cur.pose[:,3] = predicted_pose[:,3].copy() # or use motion model for translation
# populate f_cur with map points by propagating map point matches of f_ref:
# we use map points observed in f_ref and keypoint matches between f_ref and f_cur
num_found_map_pts_inter_frame = 0
if not kUseSearchFrameByProjection:
for i, idx in enumerate(idx_ref): # iterate over keypoint matches
if f_ref.points[
idx] is not None: # if we have a map point P for i-th matched keypoint in f_ref
f_ref.points[idx].add_observation(
f_cur, idx_cur[i]
) # then P is automatically matched to the i-th matched keypoint in f_cur
num_found_map_pts_inter_frame += 1
print("# matched map points in prev frame: %d " %
num_found_map_pts_inter_frame)
# f_cur pose optimization 1 (here we use first available information coming from first guess of f_cur pose and map points of f_ref matched keypoints )
self.timer_pose_opt.start()
pose_opt_error, pose_is_ok, self.num_vo_map_points = optimizer_g2o.poseOptimization(
f_cur, verbose=False)
print("pose opt err1: %f, ok: %d" % (pose_opt_error, int(pose_is_ok)))
# discard outliers detected in pose optimization (in current frame)
#f_cur.reset_outlier_map_points()
if pose_is_ok is True:
# discard outliers detected in f_cur pose optimization (in current frame)
f_cur.reset_outlier_map_points()
else:
# if current pose optimization failed, reset f_cur pose to f_ref pose
f_cur.pose = f_ref.pose.copy()
self.timer_pose_opt.pause()
# TODO: add recover in case of f_cur pose optimization failure
# now, having a better estimate of f_cur pose, we can find more map point matches:
# find matches between {local map points} (points in the built local map) and {unmatched keypoints of f_cur}
if pose_is_ok is True and not self.map.local_map.is_empty():
self.timer_seach_map.start()
#num_found_map_pts = search_local_frames_by_projection(self.map, f_cur)
num_found_map_pts = search_map_by_projection(
self.map.local_map.points, f_cur) # use the built local map
print("# matched map points in local map: %d " % num_found_map_pts)
self.timer_seach_map.refresh()
# f_cur pose optimization 2 with all the matched map points
self.timer_pose_opt.resume()
pose_opt_error, pose_is_ok, self.num_vo_map_points = optimizer_g2o.poseOptimization(
f_cur, verbose=False)
print("pose opt err2: %f, ok: %d" %
(pose_opt_error, int(pose_is_ok)))
print("# valid matched map points: %d " % self.num_vo_map_points)
# discard outliers detected in pose optimization (in current frame)
if pose_is_ok is True:
f_cur.reset_outlier_map_points()
self.timer_pose_opt.refresh()
if kUseSearchFrameByProjection:
print("search for triangulation with epipolar lines...")
idx_ref, idx_cur, self.num_matched_kps, _ = search_frame_for_triangulation(
f_ref, f_cur, img)
print("# matched keypoints in prev frame: %d " %
self.num_matched_kps)
# if pose is ok, then we try to triangulate the matched keypoints (between f_cur and f_ref) that do not have a corresponding map point
if pose_is_ok is True and len(idx_ref) > 0:
self.timer_triangulation.start()
# TODO: this triangulation should be done from keyframes!
good_pts4d = np.array([
f_cur.points[i] is None for i in idx_cur
]) # matched keypoints of f_cur without a corresponding map point
# do triangulation in global frame
pts4d = triangulate_points(f_cur.pose, f_ref.pose,
f_cur.kpsn[idx_cur],
f_ref.kpsn[idx_ref], good_pts4d)
good_pts4d &= np.abs(pts4d[:, 3]) != 0
#pts4d /= pts4d[:, 3:]
pts4d[good_pts4d] /= pts4d[good_pts4d,
3:] # get homogeneous 3-D coords
new_pts_count, _ = self.map.add_points(pts4d,
good_pts4d,
f_cur,
f_ref,
idx_cur,
idx_ref,
img,
check_parallax=True)
print("# added map points: %d " % (new_pts_count))
self.timer_triangulation.refresh()
# local optimization
self.time_local_opt.start()
err = self.map.locally_optimize(local_window=kLocalWindow)
print("local optimization error: %f" % err)
self.time_local_opt.refresh()
# large window optimization of the map
# TODO: move this in a seperate thread with local mapping
if kUseLargeWindowBA is True and f_cur.id >= parameters.kEveryNumFramesLargeWindowBA and f_cur.id % parameters.kEveryNumFramesLargeWindowBA == 0:
err = self.map.optimize(
local_window=parameters.kLargeWindow) # verbose=True)
Printer.blue("large window optimization error: %f" % err)
print("map: %d points, %d frames" %
(len(self.map.points), len(self.map.frames)))
#self.updateHistory()
self.timer_main_track.refresh()