TRACKBALL SYSTEMS AND METHODS FOR ROTATING A THREE-DIMENSIONAL IMAGE ON A COMPUTER DISPLAY

• US 20070236457A1
• Filed: 04/06/2006
• Published: 10/11/2007
• Est. Priority Date: 04/06/2006
• Status: Active Grant

• Current Assignee: Robert Smyth
• Original Assignee: Robert Smyth
• Inventors: Smyth, Robert
• Granted Patent: US 7,804,486 B2
• Time in Patent Office: Days
• US Class Current: 345/167
• CPC Class Codes: G06F 3/03549 Trackballs G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry

Abstract

A trackball rotates a three-dimensional image displayed by a computer. Displacement data is generated for designated first and second non-antipodal points on the surface of the trackball'"'"'s roller ball, for displacement of the designated first and second points during a time interval between a starting time and an ending time. The displacement data is used to generate a rotational transformation that is representative of a change in rotational orientation of the roller ball occurring during the time interval. The generated transformation is then applied to the displayed computer image to cause the image to be rotated around an image pivot point in correspondence with the rotation of the roller ball around its center.

Claims

1. A method for rotating a three-dimensional image displayed by a computer, comprising:

(a) using a trackball connected to the computer to provide input to the computer, the trackball including a roller ball having a spherical surface and being rotatable around its center point;

(b) generating displacement data for designated first and second non-antipodal points at the roller ball surface for displacement occurring during a time interval between a starting time and an ending time;

(c) using the displacement data to generate a transformation representing the change of rotational orientation of the roller ball; and

(d) applying the transformation to the displayed computer image to rotate the displayed image around an image pivot point in correspondence with the rotation of the roller ball around its center point.

2. The method of claim 1, wherein steps (a)-(d) are repeated for successive time intervals.

3. The method of claim 2, wherein the first and second points are designated at the starting time for each successive time interval.

4. The method of claim 2, wherein the time intervals are of sufficiently short duration to create a visual impression of a smooth, continuous rotation of the displayed image.

5. The method of claim 1, wherein a scaling factor is applied to the displacement data such that the magnitude of rotation of the displayed image around its pivot point matches the magnitude of rotation of the roller ball around its center point.

6. The method of claim 1, further including:

defining a set of roller ball input axes;

defining a set of axial transformations, each axial transformation corresponding to rotation of the roller ball around one roller ball axis;

analyzing the displacement data to determine which of the defined axial transformations best matches the displacement data; and

applying the best matching axial transformation to the displayed computer image to rotate the displayed image around an image pivot point in correspondence with the rotation of the roller ball around the axis corresponding to the best matching axial transformation.

7. The method of claim 1,

wherein the rotational orientation of the displayed image is represented and controlled by an image orientation matrix;

wherein the rotational transformation is represented by a transformation matrix;

wherein step (c) includes populating the transformation matrix using data derived from the displacement data; and

wherein step (d) includes multiplying the image orientation matrix by the transformation matrix.

8. The method of claim 1, wherein step (b) includes:

mapping the designated first and second points onto at least one coordinate system having an x-axis and a y-axis; and

determining the x-axis displacement and y-axis displacement of the designated first and second points.

9. The method of claim 8, wherein in step (b) the coordinate system is defined by an array of photodetectors.

10. The method of claim 8, wherein step (b) further includes:

mapping the designated first and second points onto respective first and second coordinate systems, each having an x-axis and a y-axis; and

determining the x-axis displacement and y-axis displacement of the designated first and second points in their respective coordinate systems.

11. The method of claim 10, wherein the first and second coordinate systems are defined by respective first and second arrays of photodetectors.

12. A system for rotating a three-dimensional computer image, comprising:

a computer including an image rotator for rotating the three-dimensional image around an image pivot point;

a trackball connected to the computer, the trackball including a roller ball having a spherical surface, the roller ball being rotatable around its center point,

the trackball further including at least one sensor for providing displacement data for designated first and second non-antipodal points at the roller ball surface for displacement occurring during a time interval between a starting time and an ending time; and

a transformation generator connected to the sensor for generating a transformation based upon the displacement data, the transformation representing a change in rotational orientation of the roller ball occurring during the time interval,

the image rotator receiving the transformation as an input, and applying the transformation to the displayed image to rotate the image around the image pivot point in correspondence with rotation of the roller ball around its center point.

13. The system of claim 12, wherein the sensor comprises:

at least one array of photodetectors positioned to optically detect displacement of points on the roller ball surface; and

signal processing circuitry for converting the output of the photodetector array into displacement data.

14. The system of claim 13, wherein the array of photodetectors includes means for defining at least one coordinate system having an x-axis and a y-axis, and wherein the sensor includes means for converting the output of the photodetector array into data representing displacement along the x-axis and y-axis of the coordinate system.

15. The system of claim 14, including:

first and second sensors, each sensor including an array of photodetectors defining respective first and second coordinate systems, the first and second photosensors providing as outputs data representing displacement of the designated first and second points along the x-axis and the y-axis of the first and second coordinate systems, respectively.

16. A trackball, comprising:

a base;

a roller ball seated on top of the base, the roller ball having a spherical surface and being rotatable around its center point; and

at least one sensor mounted into the base, the sensor being positioned to monitor two designated non-antipodal points on the surface of the roller ball,

the sensor generating displacement data for the designated first and second points for displacement occurring during a time interval between a starting time and an ending time, the data representing a change in rotational orientation of the roller ball.

17. The trackball of claim 16, wherein the sensor includes means for defining a coordinate system having an x-axis and a y-axis, such that the generated displacement data includes x-axis and y-axis displacement data for each of the designated first and second points.

18. The trackball of claim 16, comprising first and second sensors, each sensor including an array of photodetectors positioned to optically detect displacement of designated first and second points, respectively.

19. The trackball of claim 16, wherein the base has a rounded triangular profile, with three curved, upwardly extending support vertices.

20. The trackball of claim 19, further including at least one sensor window proximate to a vertex, the sensor window providing access between the surface of the roller ball and the sensor.