Method for smooth motion in a distributed virtual reality environment

• US 5,793,382 A
• Filed: 06/10/1996
• Issued: 08/11/1998
• Est. Priority Date: 06/10/1996
• Status: Expired due to Term

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Information Technology Center America, Inc. (Mitsubishi Electric Corporation)
• Inventors: Yerazunis, William Stephen, Waters, Richard C.
• Primary Examiner(s): Nguyen, Phu K.
• Application Number:
  US08/659,714
• Time in Patent Office: 792 Days
• Field of Search: 345/473, 345/474, 345/475
• US Class Current: 345/474
• CPC Class Codes: G06T 13/00 Animation

Abstract

A system assures smooth motion in a distributed virtual reality environmenty categorizing the information to be transmitted as to the predictability of future motion and applying appropriate smoothing algorithms based upon knowledge of what the future motion is likely to be. The system switches between a linear interpolation algorithm for less predictable data and a Catmull-Rom spline for more predictable data.

Claims

1. A system for assuring the smooth motion of a graphical object presented on-screen at a display at a recipient node on a network in which data is transmitted from a source node on said network to said recipient node, comprising:

means at said source node for transmitting data corresponding to the intended motion of said graphical object at said recipient node including an indication of the predictability of the motion of said graphical object; and

,

means at said recipient node for receiving said data and said indication, and for smoothing said data in accordance with said indication.

2. The system of claim 1 wherein said indication includes means for dividing the predictability of said data into a number of categories dependent upon the number of future points specifiable, and means at said recipient node for applying different smoothing algorithms to said data based upon the category of said data.

3. The system of claim 2, wherein for a category in which there is no predictability said smoothing algorithm includes a linear extrapolation algorithm.

4. The system of claim 2, wherein for a category in which there is maximum predictability said smoothing algorithm includes the Catmull-Rom spline algorithm.

5. The system of claim 2, wherein for a category in which there is an intermediate amount of predictability said smoothing algorithm includes a linear interpolation algorithm.

6. The system of claim 1, and further including means for angle and phase unwrapping of the rotation of said graphical object so as to eliminate boundary effects when rotating said graphical object in excess of 360 degrees.

7. The system of claim 6, wherein said means for angle and phase unwrapping includes means for ascertaining a rotation of 360 degrees plus the desired rotation, means for ascertaining a desired rotation, means for ascertaining a rotation of the desired rotation minus 360 degrees, means for selecting which of said last-mentioned quantities is closest to the previous achieved rotation for the rotation of said graphical object.

8. The system of claim 1, and further including means for reducing the bandwidth of said data by transmitting only a portion of said data dependent upon the number of intended motions of said graphical object to be transmitted.

9. The system of claim 8, wherein said data is transmitted as packets of data and wherein said bandwidth reducing means includes means for transmitting a reduced-length packet when the number of motions of said graphical object to be transmitted is below a predetermined threshold.

10. The system of claim 1, wherein said data transmitting means includes means for specifying predictability based on the number of predictable future locations for said graphical object.

11. The system of claim 1, wherein said data transmitting means includes means for specifying the predictability based the type of graphical object being depicted.

12. The system of claim 1, wherein said data transmitting means includes means for transmitting data specific for a predetermined application, said predetermined application including means for designating the predictability of motion of said graphical object, and wherein said smoothing means includes means for selecting a smoothing algorithm based on said designated predictability.

13. The system of claim 1, wherein said data is transmitted in packetized form and wherein said smoothing means includes means for recognizing redundant packets and for discarding selected ones of said redundant packets.

14. The system of claim 1, wherein said data is transmitted in packetized form, each of said packets containing redundant data, said smoothing means including means for utilizing said redundant data to generate uninterrupted motion of said graphical object in the presence of lost packets.

15. The system of claim 1, wherein said source node includes means for timestamping said data, said recipient node including means to sort said data based on said timestamps, said recipient node including means to discard old data based on said timestamps, said recipient node including means to place said data into correct time order based on said timestamps.