CamBar Offset
The CamBar offset is conducted to calculate how the CamBar is mounted relative to the main camera and is vital for good quality tracking.
This step must be repeated anytime the CamBar’s position is changed relative to the main camera.
The offset can be determined via two methods, an automatic "assistant" (recommended) or manually. Both methods are described in the sections below
This is an automatic method of calculating the offset that optically matches the views from the two cameras.
The process is quick and easy to do and requires the use of the “Instant Recovery” chart that is included with the system. Assuming the main camera lens is well calibrated and there are sufficient tracking features in the environment then this method will provide excellent results with minimal effort
It can be accessed from the “CamBar Offset” panel, a red exclamation point will also indicate here if the process has not been done yet for this tracking configuration
From this panel select “Start CamBar Offset Assistant”
The assistant provides instructions on each step of the process, for experienced users the “Skip Introduction” option will remove the instructional steps. For new or unfamiliar users, it is recommended to follow the instructions on each step.
To proceed, select “Next”
It is vital that the correct calibration is selected. From the dropdown select the appropriate calibration for the equipment you are currently using. If the calibration is not listed, please exit the calibration and add it via the equipment page before proceeding.
The lens data is also displayed on this step, please ensure that the Zoom and Focus values are correct as these will impact the quality of the offset process.
This step checks that the CamBar settings are correct. Please ensure that the IR filter is REMOVED, and that the exposure, gain, and gamma values are correctly set to allow for a good view of the environment. When correct settings are found, proceed to the next step.
Place an “instant recovery” chart in the environment.
Having stable Natural tracking features in the environment is required for this process to work well. Consider relocating the camera to an area that has features present.
Ensure that only one chart is visible in the environment, if multiple charts are detected by the system, then this can give poor results
Place the chart somewhere in the environment so that it is possible to view it from both the CamBar and the main camera sequentially. This means that it does not need to be visible to both at the same time, but that the camera can be rotated so that it can be seen in each device one after the other.
Once the chart has been placed, do not move it until the process has been completed.
The assistant will now try and detect the chart in the view from the CamBar. Adjust the main camera so that the chart is detected in the CamBar field of view. A green chart icon will be represented on the CamBar view when the chart has been detected.
For optimal results, during this step, try and minimise the number of circular markers that are visible to the CamBar
Use “next” to proceed to the next step once the chart has been successfully detected
It is now necessary to detect the chart in the main camera view. Adjust the main camera until the chart is displayed in its field of view.
If necessary, adjust the iris and focus so that the chart can be clearly seen.
When the chart has been detected, the chart icon will turn green to represent this.
The assistant is now complete.
The results of the process are displayed visually to the user by showing the relationship of the CamBar and main camera with the 3D models and their viewing frustrum's. The raw values are further displayed at the lower edge of the frame as the “CamBar Pose”.
Moving the chart during the process will cause errors or result in it failing totally. Keep the chart stationary
When the chart is being detected in the main camera view (step 5 above), it will gradually refine the offset over time, it is nearly always beneficial to allow the system 10-15 seconds to do this. Avoid completing the assistant as soon as the chart is detected
The process will struggle when working with lenses with longer focal lengths as there is less information for the system to match with. Consider swapping to a wider lens to calculate the offset where possible
This can be caused by a number of reasons:
- Chart too far away
- Chart poorly lit or obscured
- Chart too out of focus
- Tracking was temporarily lost
Exit and repeat the procedure and bear in mind the above points
If the offset assistant is giving poor results, this typically indicates that the calibration of the main camera's lens is not correct. Consider checking the quality of the lens calibration
Alternatively poor tracking features such as reflective surfaces, circular markers, moving objects, that are detected during the process can interfere. Repeat the procedure and try minimise the systems detection of these
When it is not possible or desired to use the CamBar offset assistant, a manual method is available
Simply press the padlock icon to unlock the CamBar offset values for editing. Keyboard shortcuts are available to make small adjustments easily.
Comparing the position of the tracking points in the main camera and witness camera views can be a helpful method to try and visually align the CamBar when doing it manually
Manually adjusting the CamBar offset is difficult and will typically provide poorer results than the Assistant