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The Lidar on Stencil operates at 10 hz, however to operate in real time, Stencil processes lidar
data at 5 Hz. Normally, this data is dense enough for most applications and is the maximum
density available in real time. The raw lidar data recorded by Stencil in the sensors.bag file is at
the full 10 Hz rate and can be replayed to use the full 10 Hz data in the resulting registered point
cloud. The actual time will depend on the settings in the parameter file. The parameter
skipFrameNum should be set to 0 to process the full 10 Hz. Be sure to change all instances of
this parameter as there is more than 1 in the parameter file. The default of 1 processes the data
at 5 Hz by skipping every other frame.
Users can customize Stencil 2 parameters by double clicking the desktop icon for Stencil Settings.
This will bring up a text editor with three sections. The section on the right side are the Stencil 2
default parameters. Users can modify these default parameters by copying them over from the
default side (right side of the screen) over to the user defined parameters (left side) and
modifying the left side to the desired values. Note that there are two sections on the left side.
The top left are the parameters used for live scanning. The bottom left side are the parameters
used for playback mode only. By copying and pasting the parameters from the right side to the
left side should prevent most typographic errors. Only parameters that users want to modify
need to be copied over. The user is prevented from modifying the default parameter file. Every
scanning run and every run done with Raw Data Replay will generate a .yaml file in the sub-
folder for the scan with the parameters that were used during the live scan or replay of raw data.
IMPORTANT: For replaying .bag files, turn OFF the Velodyne.
If you want to run in localization mode, change the drop down box from mapping to localization.
Be sure to choose a map for localization using the browser button on the right side of the
dialogue box before hitting the OK button.
At any time during playback, you can pause playback by hitting the spacebar on the keyboard
when the cursor is in the console window. To resume, click spacebar again.
Replaying the raw data will create a new scan folder using the original time_stamp appended
with “_replay” in the scan folder name. This feature helps to differentiate live scan data from
replayed data. The Replay folder will contain all the files normally generated during live scanning.
If you have GNSS data and the receive_gps: enabled: parameter set to true, you will also get a
gps.ply file.
After the .bag file is finished playing, a full-sized point cloud and a preview point cloud (_ds) will
be generated based on the maxPointNum parameter in the configuration file. Note that you can
stop in the middle of replay by pressing Stop Icon on the desktop or display window to finish.
The full size and preview point clouds will be generated on data processed up to that point.
IMPORTANT NOTE: The replay scan folder will contain a “hard link” to the original raw data file.
A hard link does not copy the actual file over, but it prevents the original file from being deleted
until all hard links have been removed. To say it another way, if you delete the raw data file from
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