Locating Total Station
Place the total station on the right side of the crane, with the remote head tilt pivot toward the right as shown above, if the remote head is one sided.
Align the total station roughly with the center boom pivot of the crane. The station should be 20-30 feet away from the crane, with enough distance to provide a reasonably direct measurement surface for the laser.
Important: the measurements taken from the pivot measuring points to the center of the crane are assumed to lie on the Northing axis, so the total station’s northing axis needs to be at right angles to the boom, and on the right side of the crane as shown.
- If the center pivot is blocked by the retracting weights, extend the crane forward slightly to move the weights backward.
Place a survey sticker on the center of the boom pivot as above. This provides a good survey surface, and avoids stray reflections.
Use this as the backsight point in the survey, and to set the northing direction. The northing direction should then point straight from the total station location to the boom pivot.
Measure the distance from the measurement surface to the center of the crane, and enter the survey position and thickness into the calibration UI.
Retract the crane completely before surveying other points, and verify that the boom arm is level.
Mitchell Mount Pivot
Place a survey sticker over the front pivot of the crane, referred to as the Mitchell pivot as the Mitchell mount is commonly used for underslung remote heads. Be careful to measure to the bottom pivot.
Shoot the XYZ position of the Mitchell pivot with the total station, and measure the distance from the measure point to the center of the crane. In this image, you can see the projection of the laser level at the center of the crane crossbars. Enter these numbers into the Previzion UI.
Remote Head Pivot
Place a survey target on the pivot axis of the remote head. Be careful not to move the overall crane position.
Survey the point, and enter it into the UI.
- Measure the distance from the survey point to the center of the crane’s pan axis, and enter this into the UI. Since the camera is usually centered on the remote head, this is frequently the same distance as to the center of the camera lens, but this is not always so.
Mitchell Pivot Extended
- After measuring the crane in the default position, extend the boom completely and measure the final position where the Mitchell pivot ends up. Previzion will automatically calculate the droop of the crane inbetween these two locations according to a cubic curve to account for the beam bending.