Regardless of whether active or passive 3D technology is at work, glasses-based 3D televisions rely on those glasses to selectively show each eye one of two pictures displayed on the screen. Because the two images are shot from slightly different perspectives (mimicking the slightly different views we'd see with each eye), our brain is able to put the two images together, creating the three-dimensional effect. But without glasses, both eyes see both pictures at once, creating the blurred effect that renders glasses-based 3D pictures all but unwatchable without the appropriate eyewear.
Not so UCSC's new technology, which cleverly uses a third image which remains apparently unseen to viewers, whether or not they're wearing 3D specs. Viewers without glasses will only see the left image because the right is cancelled out by the third, which is an exact negative of the right. 3D glasses mask the third image altogether.