Don’t need that extra D

I don’t have much good to say about 3D virtual worlds like Second Hype or Croquet. But what about just using 3D in the user interface for other applications? Are we going to start seeing more and more applications with 3d user interfaces? Probably some, but not very many in my view because in most cases having a 3d UI will be a bad idea.

Outside of specific domains which are intrinsically 3D like CAD/CAM etc. not much progress has been made in 3D user interfaces. I contend this is because in the end they add very little. We do see more and more 3D look in interfaces with shaded windows etc. We also see essentially 2 1/2 UIs like that in Gametap. In this case the objects in the scene are 3 dimensional but our interaction with them is still mostly 2D outside of a few effects transistions. That’s not a weakness of the Gametap design imho, it is in fact why it works. If you were really having to fly around in 3d to select games the experience would be worse overall. In most cases a 2D UI is more efficient and less ambigous than a 3d UI would be.

3D user interfaces are generally less detailed than a 2D UI for the same pixel resolution. This is mostly due to problems with rendering text correctly. Text at smaller font sizes relies on hinting and other arcane techniques to maximize readability. Just texturing it on a polygon even with good filtering an AntiAliaising will not in general look as good as a good text scan converter. Technologies like ClearType make this difference even more apparent.

Despite the fact that our binary vision an large part of our cortex are devoted to visual processing its still often very difficult to resolve what you are seeing even in some very simple cases. One can attempt to design away this ambiguity but its not so easy. Especially anytime the viewpoint has freedom of movement. While we can sense depth, our visual field is still essentially 2d and in general its better to place your design effort into optimizing that view.

Virtually all real 3d UIs involve animation. If there is no animation you won’t get much real sense of 3d and you are back to just making a 2D UI with shaded objects. The problem with this 3D animation is that it introduces delay and delay means waiting and waiting sucks. Most 2D guis now have animations as well. Menus slide into place etc. But Unless you are giving an Apple keynote the time for these animations is usually pretty fast. The transisition is complete in a time period which would cause a jarring effect if the same time was used for a 3d UI.

In summary 3D UIs are not so popular and shouldn’t be because they are:

• less detailed
• more ambiguous
• less responsive

Even though they are often Shiny® and get people’s attention.

I think we will continue to see more and more of them but I really dont expect to see them take over for 2 GUI they way 2D replaced the console. For most users the WIMP interface was a step up from the console but for most people 3D is step backwards.