The new annotation_animation parameter would create a smooth animation through the annotations at the speed of the annotation_cycle delay.
Currently the camera cycles between annotations based on annotation_cycle delays
Between annotations the camera does some sort of animation for the transition to the next annotation.
I envision an annotation_animation parameter that by default = 0.
When the annotation_animation = 1 the camera will smoothly cycle through the annotations at a speed determined by the annotation_cycle rate.
The new camera path would be a smooth path (curve) derived from an interpolated curve through the existing camera annotation positions.
This feature would essentially result in an animation path creation within sketchfab based on annotations and annotation_cycle parameters already supported in sketchfab.