Plain Text Log Formats

All data apart from images is logged to single plain text file called an “alog file”. Each line is a logged version of a message sent from a process on the vehicle – usually constituting a measurement. All alog entries have the same general syntax :

TIME MESSAGE_NAME MESSAGE_SOURCE DATA

where TIME is relative to the start of the log file (start time recorded in the log files header) that the message was logged, MESSAGE_NAME is the name of the message, MESSAGE_SOURCE is the name of the process which created the data and DATA is a string containing the data.

The data string itself is a comma separated list of string value pairs. Numerical array data is specified with a Token=[nxm]{v0,v2,v3….} syntax.

Note: We recommend that you do not use the time field in the first column of each line — it is generally not as accurate as the time fields embedded in the data strings and is (inconveniently) relative to the opening time of the log file

Relevant Data String Formats

Note you do not need to write your own parser to extract data – you can use the tools we provide.

Odometry Pose

5D pose of the vehicle in MRG frame (see Coordinate frames and the data paper).

Message Name : ODOMETRY_POSE
Message Source : iPlatform
Pose=[3×1] : Platfrom pose, represented by x,y and yaw
Vel=[3×1] : Platform velocity, represented by x, y and yaw velocity
Raw=[2×1] : Raw wheel counts from base
time : Unix time (recorded)
Speed : m/s
Pitch : Radians
Roll : Radians
PitchDot : Radians/second
RollDot : Radians/second
Sample Alog message
0.715 ODOMETRY_POSE iPlatform Pose=[3×1]{-0.0000,-0.0172,-0.0017},Vel=[3×1]{0.0000,0.0117,0.3847},Raw=[2×1]{-0.0172,-0.0017},time=1225719812.3622,Speed=-0.0117,Pitch=0.0493,Roll=0.0135,PitchDot=-0.0167,RollDot=0.0065

Raw Odometry Pose

Contains raw odometry data with roll and pitch in a frame native to the Segway hardware. Probably more useful to use the ODOMETRY_POSE message type.

Message Name : RAW_ODOMETRY_POSE
Message Source : iPlatform
Pose=[3×1] : Platfrom pose, represented by x,y and yaw
Vel=[3×1] : Platform velocity, represented by x, y and yaw velocity
Raw=[2×1] : Raw wheel counts from base
time : Unix time (recorded)(seconds)
Speed : m/s
Pitch : Radians
Roll : Radians
PitchDot : Radians/second
RollDot : Radians/second
Sample Alog message
0.715 RAW_ODOMETRY_POSE iPlatform Pose=[3×1]{-0.0000,-0.0172,-0.0017},Vel=[3×1]{0.0000,0.0117,0.3846},Raw=[2×1]{-0.0172,-0.0017},time=1225719812.36222219467163,Speed=-0.01168190181362,Pitch=0.04935378214445,Roll= 0.01346012240303,PitchDot=-0.01794682987071,RollDot=-0.00020190183605

Laser

Contains range and reflectance data from the two lasers.

Message Name : LMS_LASER_2D_LEFT/LMS_LASER_2D_RIGHT
Message Source : LMS1/LMS2
ID : Unique ID for each laser
time : Unix time (recorded)
angRes : Angular Resolution
offset : Depending on scan mode, offset values can be used to generate a higher-density scan [0 in the New College Dataset] minAngle : Minimum scan angle
maxAngle : Maximum scan angle
scanCount : Indiviual returns in each scan
Range=[181] : Individual returns
Reflectance=[181] : Individual reflectance returns
Sample Alog message
8.944 LMS_LASER_2D_LEFT LMS1 ID=77,time=1225719820.591381, angRes=0.50,offset=0.00,minAngle=45.00,maxAngle=135.00,scanCount=170, Range=[181]{1.041,1.046,…},Reflectance=[181]{38.000,37.000,…}

GPS

Contains GPS data in Northings and Eastings and metric X and Y in a local euclidean frame.

Message Name : GPS
Message Source : iGPS
time : Unix Time
N : Northing Value (degrees)
E : Easting Value (degrees)
X :Relative X (m)
Y : Relative Y (m)
Sats : Visible Satellites
Sample Alog message
2639.938 GPS iGPS time=1225722451.585,N=-7077.754,E=4177.722,X=3996.746,Y=-7164.729,Sats=5

GPS Raw

Provides the raw NMEA GPS output.

Message Name : GPS_RAW
Message Source : iGPS
NMEA Raw format from the Garmin GPS receiver
Sample Alog message
2639.938 GPS_RAW iGPS $GPGGA,145501.00,5145.24003,N,00115.02832,W,2,05,1.7,65.3,M,48.5,M,2355.0,0120*51

Control

States control inputs into the Segway Base.

Message Name : DESIRED_THRUST, DESIRED_RUDDER, DESIRED_ELEVATOR
Message Source : iJoystick
Desired Value
Sample Alog message
2639.900 DESIRED_THRUST iJoystick 89.69389935

Camera File Write Notification

Provides information about the writing of omnicam data to disk.

Message Name : CAMERA_FILE_WRITE
Message Source : iCameraLadybug
time : Unix time (seconds)
Pan : (Degrees)
Tilt : (Degrees)
GrabType :
NumImages : Number of images grabbed from the camers
File[0-4] : Write locations of all 5 images
Sample Alog message
4.194 CAMERA_FILE_WRITE iCameraLadybug time=1225719815.842,Pan=0.00,Tilt=0.00, GrabType=ladybug,NumImages=5, File0=/home/…/ladybug_1225719815.842-0.jpg, File1=/home/…/ladybug_1225719815.842-1.jpg, File2=/home/…/ladybug_1225719815.842-2.jpg ,File3=/home/…/ladybug_1225719815.842-3.jpg, File4=/home/…/ladybug_1225719815.842-4.jpg

Vehicle Geometry

Provides information about the geometry of various vehicle transforms – may be out of date.

Message Name : VEHICLE_GEOMETRY
Message Source : iPlatform
Name: Vehicle name
Sensor_[\#] Pose3D_0 = [4×1] Shape_2D = [2×8]
Sample Alog message
2641.076 VEHICLE_GEOMETRY iPlatform Name=LISA, Sensor_0=LMS_LASER_2D, Pose3D_0=[4×1] {0.0000,0.3500,0.0000,0.0000}, SHAPE_2D=[2×8]{0.3300,0.3300,…}

Status Messages

Joystick Status

Status of joystick process.

Message Name : IJOYSTICK_STATUS
Message Source : iJoystick
AppErrorFlag : Error state of the process
Uptime : Operation time in seconds

IPlatform_Status

Status of vehicle platform.

Message Name : IPLATFORM_STATUS
Message Source : iPlatform
MainBattery : (Volts)
UIBattery : (Volts)
GainSchedule :
OperationMode :

There are a few other messages logged but they have no impact on the data set.