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stopping locations of the scan to optimize the places where the Loop Closure Tool will look for
potential matches.
Match Region Horizontal
(15.0 m)
– This is the horizontal
radius
(H) in meters of the two patches to be used for matching where
the two
trajectories come close enough to each other as identified by
the
match region. Setting the value larger will increase the post-
processing time. Setting it lower will reduce the search area for
matching.
Match Region Vertical
(10.0 m)
– This is the vertical height (V)
of the
two patches to be used for scan matching. Setting the value larger will increase the post-
processing time. Returning to the case of the parking garage, you will want to reduce this value
significantly to avoid matching adjacent floors in the garage. Keep in mind that the height value is
+/- V, so you will want to set this less than half the distance between floors, as the +V of the lower
floor should not intersect with the -V of the floor above it. In other words if the floors are 3 meters
apart, you should set the V search region to 1 meter.
The combined Horizontal and Vertical of the Match Region can be considered as a cylinder if that
helps visualize what is the patches that are being aligned look like.
# of poses per stack (20) -
This is the number of 5 Hz scans to stack together before matching
back to the registered map being built. 20 scans represent about 4 seconds, while 5 scans
represent about 1 second. The default (20) can be used for slower scanning speeds such as
walking. Change it to 5 for driving applications.
The Min # will only be used if you are filtering data using the Pose Stack Confidence numbers
generated during the scanning process or in Raw Data Replay as recorded in the trajectory file.
You can select a range or force a certain number by changing the Min # and Max # appropriately.
The example here is forcing Pose Stacks of 20 frames.
Apply Pose Stack Confidence Cutoff? –
You can select one of three options here. Either do not
change the pose stack size based on the confidence values and only generate pose stacks of the
Max #. The other two options are to select the Confidence threshold using an absolute value or a
percentile value.
The purpose of the Pose Stack Confidence Cutoff is to stop adding frames to the current pose
stack if it at or above the Min # and match that pose stack back to the registered map and start a
new pose stack. If you have the time, you could set the Min # to 1 and the Max # to 20 (for
walking) which will give the essentially stack poses until you get a frame that fell below the
threshold set in the Loop Closure Tool using the values recorded while scanning or in Raw Data
