Stabilizing 360 video in DaVinci Resolve
If a video clip is affected by vibration or wobbles the effect can be very unsettling to see in a headset. While there are limits to how much this kind of problem can be fixed, stabilizing such clips in DaVinci Resolve can save otherwise unusable shots.
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Introduction
Shooting doesn’t always go perfectly; sometimes the camera support isn’t perfectly stable, and the result is clips with vibration or wobbles that are distracting to anyone watching in headsets. Fixing this is a very useful skill, but there are limits. Some kinds of instability are easier to address than others; rotational instability can be handled with frame-by-frame adjustments of the spherical media’s X, Y and Z coordinates, but bumps and other positional shifts of the camera are more challenging and may be beyond the scope of this kind of feature.
Before reaching for third-party solutions it’s always worth seeing if the camera manufacturer’s own software might do a good job of fixing the problem. For example Kandao’s QooCamStudio software has AntiShake and SuperSteady options for stabilizing footage as it is stitched, before any editing.
Stabilizing 360 media in DaVinci Resolve
If that doesn’t solve the problem DaVinci Resolve does make stabilizing a relatively straight forward, if somewhat slow, process. This is done on a clip by clip basis in Resolve’s Fusion page using the Spherical Stabilizer node. (This can be teamed with the PanoMap node if there are any leveling issues also in the mix, although at this point if the level itself is also unsteady it’s worth questioning the value of the clip in the first place.)
It is important to understand what different things the Spherical Stabilizer node can do and how to set it up. The first option is a checkbox: Reject Dominant Motion Outliers While Tracking. This ignores things that move in a different direction to the majority of the clip’s content, for example a person moving across the scene.
Stabilizing a shaky clip is a computationally intensive process, so be prepared to wait some time for this to finish.
Understanding stabilization
Stabilizing 360 media isn’t done in the same way as stabilizing normal ‘flat’ rectilinear video. In very simple terms traditional stabilizing is achieved by cropping in slightly and shifting the scene around in the frame to compensate for camera movements. However, with 360 video cropping simply isn’t possible. Instead, elements in the footage are identified and tracked, and the rotation axes of each frame are tweaked to reduce or, ideally, eliminate transient differences. This is a highly computationally intensive process and is often the most time-consuming activity in post production. This is most effective with rotational instability. Moderate vibration can also be dealt with reasonably well, but if the camera moves about in space much that can be hard for the stabilizing process to handle.
1. Add the Spherical Stabilizer node
Start by selecting the clip that needs stabilizing and going to the Fusion page in DaVinci Resolve. Then right-click the connector between the In and Out nodes and choose Add Tool > VR > Spherical Stabilizer. This new node will appear in the node chain.
2. Pick the reference frame and configure the settings
The first frame that is tracked will be used as the reference frame for the rest of the stabilization calculations. If you use the Track Backwards from Current Time or Track Forwards from Current Time the current frame is used as the reference frame, but the ‘from Start Frame’ or ‘from End Frame’ buttons will reference the start or end frame instead. This won’t always be a critical choice, but it’s a good habit to consider this and if appropriate set the playhead to the right point and use the ‘Current Time’ buttons.
Depending on the level of stabilization needed you may need to adjust the default settings; Stabilize Strength is initially set to 0.5 but larger values can be helpful. Smoothing is usually best at the 1.0 default.
3. Track and analyze the clip
The tracking controls kick off the analysis of the clip; click the appropriate button to start the stabilization analysis process. If you have chosen a specific frame as the reference point use the ‘from current frame’ forward or reverse buttons, otherwise use Track forward or Track reverse to go from the start or end of the clip. The process can be time consuming; the MediaIn and Spherical Stabilizer node labels will flash green and white as the analysis progresses.
Key settings
The Spherical Stabilizer defaults work well in many cases, but some clips may require different settings for the best final results. Start with the default settings but consider adjusting this if the results aren’t satisfactory. These are the key controls:
- Reject Dominant Motion Outliers While Tracking ignores things that move in a different direction to the majority of the clip’s content, for example a person moving across the scene.
- Tracking controls start the tracking and analysis of the clip. The options are track backward from the end frame, backward from the current frame, stop tracking (keeping the results to that point), track forward from start, and forward from the current frame.
- Append to Track defaults to replacing any existing tracking data each time this is run, but it can append new data instead. If you stabilize forwards or backwards from the current frame and want to add stabilization in the other direction, select Append before running the second stabilization process.
- Stabilization strength ranges from none (0.0) to maximum (1.0). The default is 0.5.
- Smoothing has two modes; the default setting of 1.0 smooths detected panning, rolling and tilting to improve viewer comfort, 0.0 locks the forward viewpoint only regardless of other movements, and the slider allows the strength of the smoothing to be adjusted between these two values. Again, start with the default but consider adjusting this if the results aren’t satisfactory.
Learn about the tools, techniques, work flows and best practices required for producing and delivering immersive 180 and 360 video for VR.
