Calibration
Learn how to calibrate the bike position relative to the camera for accurate measurements in Velogic Studio
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Learn how to calibrate the bike position relative to the camera for accurate measurements in Velogic Studio
Last updated
Calibration is a process which accurately defines the location and orientation of the fit bike relative to the camera, so that measurements taken during the fit are as accurate as possible.
The 5 points that are captured allow us to correct for pitch, yaw and roll so it doesn't matter whether the bike or camera is level or perfectly aligned.
To begin calibration click the button at the bottom of the liveview:
The calibration popup window will appear. You will use the wand to acquire specific points on the bike (or fit bike). The in-system help will guide you through the required locations.
The current point will be highlighted in Orange text, once the system has acquired that point the text becomes green and moves to the next location.
The system waits until the wand has been steady for 30 samples before acquiring a point. This usually only takes 1 second so it is advisable to cover the locator triangles until the wand is in position.
If you are finding that the system is not picking up a point you may need to alter the angle of the wand until the Kinect can recognise it properly.
The system will not collect another point within 50mm of the last one so there is no risk in holding the wand in one location for too long.
This video illustrates the calibration process on a trainer:
And this video illustrates the process on a size cycle (it's using the older Kinect wand, but the process is the same for Orbbec cameras and the blue wand):
Here are some more hints & tips for each point:
Stem bolt calibration point
Place the tip of the wand at the centre of the headset compression cap bolt. If you are working with bars that obscure the headset cover you will need to mark the centreline of the stem (with tape) to acquire this point. If you are using a fit bike this point just needs to be in the same plane as the next two measurements.
Centre of saddle calibration point
Place the tip of the wand at any point along the centreline of the saddle, (use your supplied green saddle jig). If using a fit bike this can be a point on the bike that is in plane with point 1 and 3.
Low midline calibration point
Place the wand at a point that is on the centreline of the bike, low down on the frame (bottle bosses are a good choice). The Kinect only needs to have line of sight to the pink locator triangles, it doesnt matter if the actual tip of the wand is obscured by a bottle cage or cable. If you are using a fit bike this point needs to be in plane with points 1 and 2.
Front pitchpoint calibration point
Rear pitchpoint calibration point
The pitch points are two locations of equal height (when the bike is on level ground). These points are used to correct for the camera being rotated relative to the bike - either because the camera is rotated on its mount, or because the bike is pitched up or down at the front or back, e.g. because it's mounted on a stationary trainer.
The wheel axles are a good choice if both can accessed - in which case you would choose the front wheel skewer for the front pitch point and the rear for the rear pitch point.
If you're using a fit bike (which doesn't have axles), it's likely that the bike is always level relative to the ground - so you can a point on the floor in front the bike for the front pitch point; and on the floor behind the bike for the rear pitch point.
Once the process is complete click the "Finish" button.
Calibration is always required if you're going to use the wand to measure the bike. Otherwise, it's optional.
If you don't calibrate:
You won't see the Sitting Angle body metric (because that references the bottom bracket, which is established during measurement; and measurement always requires calibration).
Most of the body metrics will still be very accurate, especially the basic joint angles (because these are measured between points in 3D space, so the camera orientation does not matter)
Some of the body metrics will be less accurate IF the bike has pitch, roll or yaw relative to the camera:
Hip-to-foot (will be less accurate if the bike has "yaw", "pitch" or "roll" relative to the camera)
Knee-over-foot (will be less accurate if bike has "yaw" relative to camera)
Torso angle, forearm angle, and arm angle (will be less accurate if the bike has "pitch" relative to the camera i.e. front and rear axles aren't level relative to the camera)
Knee travel angle and knee lateral travel (will be less accurate if the bike has "roll" relative to the camera)
Knee tracking visualisation will be less accurate - e.g. if the camera is angled down towards the rider's legs, the knee track will appear to be on an angle even if the rider's knee is actually travelling completely vertically.
... so, if you're not going to calibrate, you should try to ensure that the camera and bike are both level with the ground, and the camera is pointing directly at the bike (i.e. not on an angle left/right or up/down).
In Velogic Studio v4, we added a Calibration Review step for this purpose.