Jerk and jounce is a Performance Capture term in filmmaking. In virtual production, the nuances of this term take on special meaning. Here, we break down the definition to give you a starting point.
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In layman's terms, jerk and jounce refer to derivatives of acceleration that can cause significant issues when using motion control technology. To prevent these issues from happening, there are several steps you need to take into consideration.
Jerk is defined as "a sudden sharp movement or change in direction," while Jounce refers to an "abrupt, jerky bouncing." Both terms have a direct correlation with motion control, where any abrupt movements or changes in direction can throw off the accuracy of the scene being filmed. For example, if you were filming a car chase scene on a track and the camera was moving along a curved path, jerk and jounce could cause problems with timing, precision and overall smoothness of the shot.
The main way to avoid jerk and jounce in virtual production is to set up clear boundaries around the movements you want your characters or objects to make. This includes using tools such as velocity-based speed curves and limiting parameters like max speed or acceleration. By doing this, you can create more predictable, controlled motions without compromising the feeling of organic movement. Additionally, setting limits on the range of motion can also help reduce errors caused by Jerk and Jounce.
Ultimately, preventing jerk and jounce in virtual production takes practice and patience. Understanding how different elements interact and affect one another will go a long way towards creating smooth transitions and accurate results. However, even after taking all the necessary precautions, some unexpected jerks and jounces can still occur. It's important to be prepared to respond quickly and appropriately should anything occur during filming so that the final output looks its best.