J. Liang. Jdcad: A highly interactive 3D modeling system. Computers and Graphics, 18(4):499--506, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....VEs takes advantage of the fact that menu selection is essentially a one degree of freedom (DOF) operation to provide an important constraint. In these 1 DOF menus, the user controls only one parameter, such as wrist rotation about a single axis, to place the desired menu item in a selection box [7, 15]. These menus can be fast and accurate, but performance suffers when the number of commands becomes large. Moreover, because they use only 1 DOF, there is no notion of a menu hierarchy; instead, the menu is simply a list of commands. Finally, Mine [16] has explored body centered menus, in which ....

Liang, J. and M. Green, JDCAD: A Highly Interactive 3D Modeling System. Computer & Graphics, 1994. 4(18): p. 499-506.

....interface, the other interfaces should represent the state of the art. Two competitive interfaces were chosen: a mouse based interface that is a simplified clone of the Alias modeler [1] and an interface that uses a single button enhanced 3D tracker in a similar style to JDCAD, developed by Liang [7]. Figure 2: The button enhanced bat. The Mouse Based interface was selected from among the best professional CAD systems commercially available. The intent of this experimental comparison was to compare the new technology against the toughest level of competition. However, to avoid swamping the ....

Jiandong Liang and Mark Green. JDCAD:A Highly Interactive 3D Modeling System. Computers and Graphics, 18(4):499--506, 1994.

....is one example: users can move instantaneously between locations regardless of the distance between them. The destination can be chosen in a variety of ways, including pointing to the desired location on a 2D map [Angus] or returning to a previous spacemark (essentially a bookmark in space) [Liang]. Mine created a head butt zoom technique [Mine] that allows users to create spatial non linearities on the fly. Users frame a distant object with their hands on their image plane to create a temporary window frame in space. Sticking their head through this window causes their viewpoint to zoom ....

....[GSmith] allow an individual s view of the world to be tailored specifically for that user s tasks or interests. A property of objects that is usually even more taken for granted is that objects are persistent: you cannot create or destroy them on demand. 3D modeling programs (e.g. Zeleznik][Liang][Butterworth] break this assertion all the time, we can break this assumption for other reasons as well. Creating and destroy objects on the fly allows the user to work with a large number of different widgets without cluttering up his environment. With Pierce s Voodoo Dolls technique ....

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Jiandong Liang and Mark Green. JDCAD: A Highly Interactive 3D Modeling System. Third Conference on CAD and Computer Graphics, 1993, pages 217-222.

....To simplify selection the width of the cone is interactively adjustable. In object selection mode, a semi transparent cone projects from the front of the tricorder (see Figure 6) The cone determines which object is selected when the user presses the select button, similar to selection in [10]. By incorporating a spotlight at the apex of the cone, we enhance visual feedback by literally highlighting the objects to be selected. In addition, we ease selection by allowing the user to control the width of the cone interactively. Once an object is selected, the user can rotate or translate ....

J. Liang and M. Green. JDCAD: A highly interactive 3d modeling system. In 3rd International Conference on CAD and Computer Graphics, pages 217--222, Beijing, China, August 1993.

....in VE [3] can significantly limit their appropriate use in VE design. Interaction techniques essentially define the look and feel of VEs; a wide variety of techniques can be implemented using the same input devices and quite a few techniques for spatial manipulation have been demonstrated [7, 15, 16, 17]. Still, there have been few attempts to formally evaluate techniques for manipulation in VE, assess their functional capabilities, and compare their relative strengths and weaknesses. A number of surveys have summarized and classified various approaches for designing techniques for spatial input ....

....techniques. Starting with early techniques that simply mapped position and orientation of the user s hand onto position and orientation of manipulated objects [20] the field has been expanding with more sophisticated techniques such as flash light, aperture, Go Go, World In Miniature technique [7, 11, 15, 17, 21] and others. This variety of techniques, however, is also a source of difficulty. How do all these techniques relate to each other Which interaction techniques should be chosen for particular task conditions Which among the parameters of interaction techniques, tasks, and environments should be ....

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Liang, J., JDCAD: A Highly Interactive 3D Modeling System. Computers and Graphics, 1994. 18(4): pp. 499506.

....was unimanual. A similar map cube concept was referred to as the God s eye view in the super cockpit project [11] Previous Work in Object Selection Many researchers have explored methods for selecting objects in a virtual world. Common approaches include raycasting [10] 23] and selection cones [15]. Both of these techniques suffer from object occlusion and therefore need to be tied closely with some mechanism that can quickly establish different points of view. Put That There [3] used selection via a combination of pointing and naming (or description) Pointing in this two dimensional ....

....in the middle to suit the requirements of the task. For example: the user can reach into the WIM to select a distant object (taking advantage of the greater than 1:1 scale of the WIM) and then reach out to the immersive world to move the WIM selected object at a distance in 1:1: scale [23] [15] all the while viewing the scene in the WIM. Rotation Our current implementation allows users to rotate objects, through ratcheting (repeated grabbing, rotating and releasing) 25] and is therefore more awkward than a rotation done with just the fingers [15] Interestingly, some users found it ....

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Jiandong Liang, Mark Green. JDCAD: A Highly Interactive 3D Modeling System. In 3rd International Conference on CAD, pages 217-222, August 1993.

....objects even a short distance away are difficult to select reliably or consistently. Similarly, positional noise adversely affects the usability of the touch technique ( Sigma1:5 inches) Also, the touch technique can only be used to select objects that are within reach. The spotlight technique [5] is a variation of the laser pointer technique. It reduces the effects of noise and object size problems by using a conic selection volume. Because all the objects within the conic selection volume may be selected, however, a disambiguation metric for choosing a single object from the set of ....

Jiandong Liang and Mark Green. JDCAD: A highly interactive 3D modeling system. Computers and Graphics, 18(4):499--506, July/August 1994.

....was unimanual. A similar map cube concept was referred to as the God s eyeview in the Super Cockpit project [11] Previous Work in Object Selection Many researchers have explored methods for selecting objects in a virtual world. Common approaches include raycasting [10] 22] and selection cones [14]. Both of these techniques suffer from object occlusion and therefore need to be tied closely with some mechanism that can quickly establish different points of view. Put That There [4] used selection via a combination of pointing and naming (or description) Pointing in this twodimensional ....

....in the middle to suit the requirements of the task. For example: the user can reach into the WIM to select a distant object (taking advantage of the greater than 1:1 scale of the WIM) and then reach out to the immersive world to move the WIM selected object at a distance in 1:1 scale [22] [14] all the while viewing the scene in the WIM. Rotation Our current implementation allows users to rotate objects, through ratcheting (repeated grabbing, rotating and releasing) 24] and is therefore more awkward than a rotation done with just the fingers [14] Interestingly, some users found it ....

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Jiandong Liang, Mark Green, JDCAD: A Highly Interactive 3D Modeling System. 3rd International Conference on CAD, pp. 217-222, August 1993.

....hand for low frequency) 2 3 Draw uses this natural division of manual labour by assigning the (low frequency) setting of spatial context to the left hand, and the (high frequency) selection and picking operations to the right. Jiandong Liang at University of Alberta built a system called JDCAD [20, 21] which uses a single Polhemus sensor to create 3D mechanical parts. The user creates items by selecting a primitive from a Polhemus based ring shaped menu and dragging out the bounding box. The user can then select objects, reshape them either freely or along a constrained axis, and group them ....

....this condition by disallowing edits of these vertices. 4.2 Geometry of Control Point Selection Given that the user desires a control point, this section describes how the user geometrically controls the right bat to pick the desired point. We use a probe selection technique similar to Liang s [20, 21] spotlight. A probe, represented by a narrow cylindrical shaft, is attached to the right cursor, and the user controls the position and orientation of the probe with the right bat. The distance from this probe is computed for each control point using a specialized distance metric called the probe ....

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Jiandong Liang and Mark Green. JDCAD: A Highly Interactive 3D Modeling System. Computers and Graphics, 18(4):499--506, 1994.

....and recording their transformation matrices. When the behavior is triggered at run time these matrices are interpolated to produce the motion. The second geometrical modeler, JDCAD 2. 0, extends the previous solid modeler by adding CSG operations, and uses a better set of interaction techniques [4]. The ring menu described in section 3.1 is used for primitive object selection in this modeler. The interaction techniques described in section 3.3 can be used to create sub objects, modify their shape, and position them with respect to each other. In addition, CSG operations can be performed ....

J. Liang and M. Green, JDCAD: A Highly Interactive 3D Modeling System, Computer and Graphics 18, 4 (1994), 499-506.

....data can also be shared between peers. Any MR Toolkit program may start up the peer package at any time, and may initiate and quit communications with other processes at will. Peers are connected pairwise and one peer may send a message to any or all other peers using procedures. JDCAD [12, 14] is a solid modeling and animation computeraided design system. It uses a Polhemus or Ascension 3D tracker to sweep out 3D canonical shapes such as boxes, cylinders, cones and the like. These shapes can be reshaped, joined together and connected in kinematic chains. JDCAD has a keyframe animation ....

Jiandong Liang and Mark Green. JDCAD: A Highly Interactive 3D Modeling System. Computers and Graphics, 18(4):499--506, 1994.

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J. Liang. Jdcad: A highly interactive 3D modeling system. Computers and Graphics, 18(4):499--506, 1994.

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Jiandong Liang, Mark Green, JDCAD: A Highly Interactive 3D Modeling System, Proceedings of the 3rd International Conference on CAD and Computer Graphics, 1993. 217-222.

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J. Liang and M. Green. JDCAD: A highly interactive 3d modeling system. Computers & Graphics, 18(4):499--506, 1994.

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Liang, J., Green, M., JDCAD: A highly interactive 3D modeling system. Computer & Graphics, 1994. 4(18): pp. 499-506.

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J. Liang. Jdcad: A highly interactive 3D modeling system. Computers and Graphics, 18(4):499--506, 1994.

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