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Setup of the Caveatron is easy - all that is required is to charge the battery and if 3D scanning is to be performed, the LIDAR is attached to the top rail with thumbscrews and it is ready to go. If many weeks have elapsed since it was last used, a simple, one minute calibration procedure can be performed involving rotating the instrument over many angles of a sphere. Each survey is stored in a different file, so at the beginning of a new survey, the name is entered (typically the cave name) and the date is automatically added to make it distinct. 

SHOT Mode is used for collecting station to station distance, azimuth and inclination measurements to generate a line plot of the cave. These vectors are also used as the backbone for the LIDAR scans. First the names for the “from” and “to” stations are entered (either automatically chosen or manually typed in). The red laser comes on so that the Caveatron can be aligned to the next survey station. The bottom rear corner is placed on the current station and the left of right may be selected on screen depending on which is more convenient. It can be held upright or upside down (if your station is on the ceiling), and this is accounted for in the software. A large button is used to activate the shot and an audible tone indicates when the shot has started and finished. A shot takes less than 3 seconds, during which 3 distance, measurements and 900 azimuth and inclination measurements are taken and averaged. At the end of the shot, the measurements are shown on the screen and the shot can be accepted or redone. If a problem occurred, such as the Caveatron moved during the measurement, the shot will fail which is indicated by a special low-pitched tone. The Caveatron is also setup to quickly perform dedicated back-sights that are averaged with the front-sights to improve accuracy.

PASSAGE Mode is the main method for taking LIDAR scans. It is performed by gradually traversing the Caveatron (by walking, crawling, climbing, etc) toward the reference station. As with SHOT mode, PASSAGE Mode starts by entering the station to which the traverse will be made (again auto-filled from the last shot) and a traverse number. After pointing the laser at the station the user taps a button the screen to measure the starting position, and when ready, tap again to begin the LIDAR scan. As you move forward, you attempt to keep the laser pointed at the card. It's not required to constantly hit the card as that would be nearly impossible while moving, but just to hit it periodically and not stray the laser pointing angle too far away for too long. The Caveatron beeps whenever it gets a valid position reference off of the card as feedback. If you move too fast either forward or backward, too much time passes between valid measurements, or if the angle changes too suddenly, the Caveatron will stop the traverse. When the traverse is finished, colored statistics are shown in the screen to indicate the quality of the data. You can then chose to do another traverse, redo the previous traverse or return to the main screen.

The last survey mode is ROOM Mode which is used to capture LIDAR scans of areas that PASSAGE Mode might miss, such as alcoves, passage corners or ends, or rooms that don’t continue. In ROOM Mode the Caveatron is not moved, but held on a fixed location (such as on a rock) and is rotated in an arc or complete circle. For this mode, the LIDAR only scans to the left side, so that the operator can position themselves on the right side to avoid being scanned. Prior to starting the scan, the reference station and splay number are entered and an initial position measurement is acquired by tapping a button. A second button tap begins the LIDAR scan and you very slowly spin the Caveatron until the desired area is covered. As with other modes, statistics and redo options are displayed after the scan is complete. This mode is probably the best way to safety scan pits. The idea is to descend to a certain point, stop and scan, descend a bit further and repeat until you get to the bottom.

A MANUAL Mode is provided to obtain quick distance, azimuth or inclination readings without having to enter station codes. However, no data is saved and is only displayed on the screen.

The SURVEY menu is used for initial survey setup, to view statistics for the current survey (such as length, depth and number of shots), to view and edit a list of the shots, and view the line plot of the current survey. Plan and profile views as well as station labels can be displayed. Loop closures are detected and indicated on the screen so you can quickly see the quality of the closures by how close they are. The current station is also highlighted to quickly orient your position. Individual LIDAR scans in the current survey can also be reviewed as plan view and profile view slices. In the SETTING menu there are a variety of functions to set the date and time and view information about the system and SD card, and perform re-calibration. When the LIDAR is attached, a screen is available to show a live view of the scan, which helps in determining if you are getting the coverage you want. 

The calibration of the accelerometer, magnetometer misalignment, and other parameters are done when the Caveatron is assembled and are stored in internal memory. Additional magnetometer calibration (hard and soft iron) is done by the user as it can drift over the course of several weeks and needs periodic updating. This is done by simply rotation the unit through as many angles of a sphere as possible. The Caveatron automatically collects the points until it has as many as it needs and completes the calculation automatically. Separate calibrations are stored and loaded depending on whether the LIDAR is attached or not.


Shot Mode

Measures distance, azimuth, and inclination between two stations.


Passage Mode

Performs a continuous 360 degree LIDAR scan while traversing toward a station.


Room Mode

Performs a 180 degree LIDAR scan while rotating in place either referenced to a nearby station or on the station.

© Copyright 2017 Joe Mitchell