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Decoding Technique Giving an Arbitrary Angle From Outputs of A Pointing Device

IP.com Disclosure Number: IPCOM000101632D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 86K

Publishing Venue

IBM

Related People

Miyazawa, A: AUTHOR

Abstract

A new decoding technique giving an arbitrary angle from the outputs of a pointing device is described. The technique utilizes a pointing device, such as a mouse or a trackball, whose relative movements in two orthogonal directions are reported. By calculating the weighted sum of these directions received up to any point, the method makes an arbitrary angle available to the computer, as well as the position of the screen cursor. Such a technique contrasts with conventional modal operations for specifying the angle, in which the user must first enter the mode, and then obtain the angle in a different way from that in which he positions the cursor. In this method the user can obtain both the position and the angle simultaneously.

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Decoding Technique Giving an Arbitrary Angle From Outputs of A Pointing Device

       A new decoding technique giving an arbitrary angle from
the outputs of a pointing device is described.  The technique
utilizes a pointing device, such as a mouse or a trackball, whose
relative movements in two orthogonal directions are reported.  By
calculating the weighted sum of these directions received up to any
point, the method makes an arbitrary angle available to the computer,
as well as the position of the screen cursor.  Such a technique
contrasts with conventional modal operations for specifying the
angle, in which the user must first enter the mode, and then obtain
the angle in a different way from that in which he positions the
cursor.  In this method the user can obtain both the position and the
angle simultaneously.  Since the method can be implemented with a
minimum of support software, a conventional pointing device can be
utilized.

      The decoding technique reported here employs one kind of
pointing device, such as a mouse or a trackball, which consists of a
ball connected to shaft encoders that deliver electrical pulses for
every incremental rotation of the ball, as shown in Fig.  1. The
pointing device's movement in two orthogonal directions is translated
into rotation of the ball.  These rotations can be measured by
counting the pulses received from the shaft encoders.  The converted
values may be held in registers accessible to the computer or written
directly into the computer's memory.

      As described above, the pointing device can report only four
relative movements in two orthogonal directions, namely "Left,"
"Down," "Right," and "Up."  Consider, however, generating one of 24
directions separated by intervals of 15 degrees out of a combination
of these four directions separated by intervals of 90 degrees.  Since
the logarithm of 24 to the base 4 is

      360 / 15 = 24 = 4 ** 2.2925 <= 4 ** 3
the direction can be obtained by calculating the weighted sum of
these directions previously received.  Here, let these weights be 2,
sqrt (3), and 1. When the pointing device moves between the same
points, from poin...