Summary: Ramesh Raskar (firstname.lastname@example.org)
In this breakout session we discussed augmenting physical objects by projecting imagery of virtual 2D or 3D objects on them. The questions posed to the group were:
Most of the participants already had some experience with using projectors for VR or large displays using tiled setups.
The participant thought that the main advantage of using projectors is the comfort. We discussed the following benefits :
- Human factors, ergonomics and safety : A user is usually less efficient with HMD-based AR due to the lack of comfort and limited peripheral vision. Our guess was that users would like to keep the computation and display elements away from their bodies. Most participants thought that this benefit is very significant and offsets all the limitations of projector-based AR systems (such as shadows).
- Multiple users: Similar to tiled-displays, projector-based AR is ideal for collaboration because everyone can simultaneously see (the real and) the synthetic data. This can also be a disadvantage, however, because one cannot have a personalized view.
- Large amount of data and high resolution: The number of pixels are dependent on only the number of projectors (and their resolution). Hence, very detailed, wide-field-of-view images can be generated. One of the major limitation of current-generation HMDs and hand-held displays is the pixel-resolution and temporal resolution (frame-rate). Both these problems are reduced by using multiple projectors.
- Reduced head-tracking requirements: When virtual objects are just 2D text, arrows or data that remains registered with surfaces of physical objects, no head-tracking is required.
However, the major problems are :
- Infrastructure and Power: Although projectors are getting lighter, they need an infrastructure for setup and image generation. The power requirements are also higher.
- Surface of projection : The objects on which images are generated need to be simple (smooth), diffuse and light colored.
- Interaction problems and shadows: It is difficult to represent say 'laser pointers' for interaction. Shadows can occlude important features. (Although shadows could be a problem, we thought that the goal of AR is not necessarily 'immersion' (e.g. creating a virtual world) and a user will be willing to tolerate shadows or resulting break-in-presence.)
- Assembly line, wiring bundles, car manufacturing: Industrial environments where the working volume remains static.
- Entertainment and games: At amusement parks, projectors are already being used to project dynamic images to augment static models.
- Advertising and presentation: In windows of shops, latest models can be shown in different colors or textures. At trade-shows, information can be projected on products.
- Education, training, design and planning: Procedures or data can be inserted during training, architects can visualize tabletop models with different attributes by changing projected imagery.
We wondered whether projector-based AR will be taken seriously in the future.
- Time will improve HMDs : Many factors about HMDs (e.g. weight, resolution, comfort) will improve over time and then many advantages of projector-based AR over HMD-based AR will become insignificant. However, some of the participants believed the projectors will become correspondingly better and easier to use. For example, the brightness will increase, size will decrease and it will be possible to transmit images to projectors over wireless networks.
- Cost and maintenance : Which display technology is cost effective and easier to maintain ? There was no clear agreement on this
- Other technologies: Are there other new technologies ? One of the participant mentioned electronic paper or electronic ink, which may be used in the future to change appearances of physical objects (by pasting the paper on the object).
All the participants were
enthusiastic and optimistic about exploring projector-based AR. The final comment was :
"If you are planning to build an AR system, head-mounted or hand-held displays are not your only choices. Do consider projector-based augmentation."