Synchronization Validation Tool
A handy tool to assess whether hardware synchronization is working properly and be able to troubleshoot potential PCB assembly issues.
Whenever precise hardware synchronization of the RGBD devices is needed, it is recommended to use this tool to confirm that there are no hardware problems.
Synchronization Validation Tool, as its name implies, is a tool to validate the hardware synchronization of our Volumetric Capture system. Hardware synchronization means that every RGBD device in the system is capturing simultaneously after being triggered by a master clock, which is a vital requirement for multi-view capturing systems that need to reconstruct scenes with quick motion(s).
Synchronization Validation Tool works on the assumption that, if all cameras in a system are synchronized, then they ought to capture exactly the same thing. To this end, we use a momentary but bright light source (a camera flash), expecting this light to appear simultaneously in all views. Furthermore, inspired by this work, we achieve bigger confidence of synchronization validation exploiting the rolling shutter technology, on which RealSense D415 is based and which is our main device for the time. A group of hardware synchronized frame, capture by a rolling shutter-based device looks like this.
Notice that the brightness discontinuity in all frames is at the same position (i.e. image row). For further information on this topic please refer to this work.
In order to use Synchronization Validation Tool, a set of discrete steps are needed. Firstly, the Volumetric Capture application must be set as follows:
- Connect all devices and interconnect them with the hardware sync cable
- Choose a Master device for hardware synchronization (see more details here)
- Choose a stream profile with RGBIR as its color stream
- Connect the devices
- Synchronize the remote nodes
- Start the synchronization process
- Start publishing synchronized frames
Once the above steps have been successfully accomplished, it is time to use the Synchronization Validation Tool. Upon running the executable, a login-like window will show up, where the broker information must be inserted.
Once connected to the broker, grouped frames should appear in the application window. Next step is to adjust the MAD factor as described at the troubleshooting window in the software. When the appropriate MAD factor is selected, the user can trigger a bright visible and infrared light flash (or something with similar behavior to produce momentary bright light), preferably towards the center of the capturing station. Once flash event is detected, another windows will appear that stores the grouped frames that contain a flash event. Examination of these frames by the user will let her/him determine whether hardware synchronization is working (as explained in the "How does Synchronization Validation Tool work?" section.
