The first factor cited is an improvement in accuracy. We heard reports of problems with precision at GDC 2014, but I don’t believe a busy expo floor is a suitable environment for testing what the consumer experience will be like. Sixense states “[their] engineers have identified a novel way to greatly reduce or eliminate environmental distortion (often referred to as “bending”) that will significantly improve accuracy and further ensure a consistent and reliable experience in different environments and for a wider range of VR applications,” and goes on to add that this is in addition to other accuracy improvements previously publicized.
The second factor is a redesign of how the STEM (standalone position tracker) and STEM Pack (battery and clip) interact. Previously these were two separate components, but Sixense discovered “the design of our STEM module introduced significant electronic noise (which required too much filtering, which adds latency) and mechanical instability (which translates to inconsistent, sometimes unreliable tracking data) to the system.” To correct this, the individual STEM and STEM Pack have been joined into a single module.
For the tracking modules, this means the battery pack and tracker have been combined. The original design featured a separate tracker that could be integrated with other controllers:
The controller also would’ve had a removable tracker, as shown:
The revised design shows the combined components:
For the controller itself, the tracker is no longer detachable and is instead affixed.
The general consensus on the Oculus sub-section of Reddit and the Kickstarter page is mostly supportive of Sixense and the decision, with many expressing that they’d rather Sixense take the extra time to deliver a solid system.
SixenseVR SDK Coming Soon
The SixenseVR SDK will allow developers to integrate with STEM and the Razer Hydra.
SixenseVR supports any number of trackers, which can be placed on any part of the body. The head position tracking can come from a STEM Pack tracker, the HMD itself, or a fusion of the two for a calibration free experience. Even with only HMD tracking, SixenseVR will match the pose of the avatar to the position and orientation of the head, providing body awareness with realistic-looking leaning and crouching.
The company recently put out a video preview showing how easy it is to get up and running with STEM and the SixenseVR SDK in Unity.