Week 12 Summary

A Survey of Design Issues in Spatial Input

This paper is about a survey of design issues for free-space 3D interface. The issues are described using examples from 3D interface instances.

The issues they study are:

1. Users’ difficulty understanding 3D space.

In this part they mainly talk about that “using a spatial reference is one way to provide this perceptual experience and to serve as a source for relative gestures”. They also reinforce findings that “users can transfer everyday skills for manipulating tools with two hands to the operation of a computer”. Physical manipulation of tools with mass can provide better multisensory feedback. Using a combination of physical and software constraints works well.

2. The trade-off between multidimensional tasks and independent input dimensions.

In this part they discuss that the designers should know whether the intended user perceive of three dimensions as related or independent quantities. It is good to reduce dimensions based on the specific needs of tasks.

3. Control metaphors

They added a fourth metaphor, ray casting metaphor, based on the previous three, which are “eyeball in hand”, “scene in hand” and flying vehicle control.

4. Dynamic target acquisition

They give a general discussion on the use of transparency to facilitate target acquisition. And later they compare solutions to 3D point selection and 3D object selection.

5. Recalibration mechanisms

Here they introduce three recalibration strategies. They are “commanded based”, “ratcheting” and “continuous” realibration. The strategies can be composed based on what the tasks are.

6. Ergonomics and Facility of Interaction

This section is about how to overcome the difficulty in using interface requiring precise control of an object’s position and orientation. They introduce some previous work and state that it is still challenging.

7. Working volume of user’s hand

Users tend to define a working volume for their hand movement during a task. So a interface requiring movement relative to a fixed frame-of-reference may not be efficient.

8. Mice and Keyboard

They argue that it is bad method to switch between spatial input devices and traditional ones. The alternatives can be voice input and touchscreen.

9. Clutching mechanisms

They talk about a software mode in which the spatial input device and be moved without affecting the cursor. They worry about that the bad design for clutching mechanism can lead to usability problems. Snapshot of a screen may totally replace the use of clutching mechanism.

10. Ergonomic details

The last section is to help users reduce fatigue as much as possible. The strategy can be movement of body, adjustable height of chair and bread reminder.

Question: In the experiment about multisensory feedback, is it possible to change the design of the glove to make it work as well as tracked physical flashlight?

Exploring 3D Navigation:

This paper concentrates on a task-based taxonomy of navigation techniques for 3D virtual environment. They introduce a new technique called :Speed-coupled Flying with Orbiting” in details. Some user tests are carried out to prove that users perform better with this techniques over others.

At first some basic concepts are categorized and discussed. They believe navigation can be broken into three tasks, which are exploration, search and inspection. Designers should help users have a good control of path and view, and develop an effective interface at the same time.

The techniques they consider in the study is inspection, search and and model tasks. In these sections they introduce how some existing techniques deal with these problems. Later their experiments are talked about in details based on them.

17 participants joined the first experiment to evaluate five navigation techniques. A tutorial world and a experiment world were designed and each world had target cubes and target drop-pad. And the tasks for participants are to drop the cube into the drop-pad. The final result showed that Speed-coupled Flying with Orbiting was reliably faster than other techniques and users satisfied with it.

The second experiment was to Flying with Orbiting was a significant improvement beyond Basic navigation in 3D world. The added a gliding behavior to Flying with Orbiting to alleviate users’ difficulty in knowing where they were going to land. 13 people participated it and performed similar tasks. Finally they found that Flying with Orbiting and Glide navigation is the fastest and 9 of the 13 people preferred it.

Question: Will the results be different if the type of tasks is changed?

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