Image analysis – Applications – 3-d or stereo imaging analysis
Reexamination Certificate
2002-07-29
2004-11-23
Mehta, Bhavesh M. (Department: 2625)
Image analysis
Applications
3-d or stereo imaging analysis
C382S312000, C382S305000, C348S042000, C359S462000, C352S086000, C356S012000
Reexamination Certificate
active
06823080
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional information processing apparatus and method for extracting three-dimensional information, that can be used in CG, CAD, and the like, from an object having a three-dimensional shape.
As a conventional technique for obtaining the three-dimensional shape of an object, for example, “Stereoscopic matching using a plurality of base line distances” (
Journal of Papers of the Institute of Electronics, Information and Communication Engineers
D-II, Vol. J75-D-II, No. 8, pp. 1317-1327, August 1992) is known. Generally, the conventional method of acquiring a three-dimensional shape can be roughly classified into passive and active methods.
One typical passive method is a stereoscopic image method, which utilizes trigonometric measurements using two cameras. In this method, the positions of images of an identical object are detected from right and left images taken by cameras, and the three-dimensional position of the object is measured based on the displacement amount between the detected positions.
As typical active methods, an optical radar type range finder which obtains distance by measuring the time until light projected toward and reflected by an object returns, a slit light projection method for projecting a slit-shaped light pattern onto an object, and measuring the three-dimensional shape on the basis of the displacement of the pattern shape formed on the object, and the like are known.
Note that the three-dimensional data of the object obtained by the above-mentioned methods can be reproduced and displayed on, e.g., a two-dimensional display.
However, the stereoscopic image method has as its major objective to calculate the distance information from a specific position where the cameras are set to the object, and does not measure the three-dimensional shape itself of a certain object. In the active methods, since a laser beam or the like must be irradiated onto the object, it is cumbersome to use such methods.
For this reason, such methods cannot flexibly cope with a dynamic image sensing environment, i.e., image sensing while moving around a certain object, and hence, none of the conventional methods can extract depth information in such dynamic image sensing environment.
Images normally used in an office are often finally output onto paper sheets, and images types to be used include both natural images and line images that express objects by edge lines alone. More specifically, in an office or the like, it is a common practice to process image information for various purposes.
In contrast to this, since the principal object of the above-mentioned prior art is to calculate the three-dimensional shape data of the object from certain specific setting positions of the cameras and to faithfully display the calculated data on a two-dimensional display, the above-mentioned methods cannot cope with various kinds of image processing required in, e.g., an office.
More specifically, the present invention is addressed to a three-dimensional information extraction apparatus which can be easily applied to a dynamic image sensing environment in which the image sensing position changes, and can process acquired three-dimensional information into various forms.
Some stereoscopic image processing apparatuses use three or more images in place of two images, and form three-dimensional shapes by unifying shape information obtained from such images.
Upon judging the reliability of the obtained three-dimensional shape, for example, the above-mentioned stereoscopic image method uses the comparison result or correlation of residuals obtained upon calculating the position displacement amount by corresponding point extraction of the luminance values in place of reliability judgment.
However, in the above-mentioned prior arts, in the case of, e.g., the stereoscopic image method, even when the residual is large or when the correlation function is small, if the angle the object makes with the image sensing plane is large or the distance from the apparatus to the object is large, calculation errors due to minimum errors of the corresponding extraction results are large, and the obtained three-dimensional shape has low reliability. On the other hand, the obtained three-dimensional shape is not displayed considering its low reliability.
That is, the present invention is also addressed to improvement of reliability in three-dimensional information processing.
On the other hand, the present invention is addressed to storage of image information in the dynamic image sensing environment. Problems associated with storage of image information in the dynamic image sensing environment will be discussed below.
In a certain prior art associated with the dynamic image sensing environment, a single image sensing unit placed on a rail is translated to sense a plurality of images, and shape analysis is made using the correlation among the sensed images.
In addition, Japanese Patent Publication No. 7-9673 is known as the technique of analyzing the shape of a stereoscopic object using the correlation among two pairs of parallax images sensed at the same time using a compound-eye image sensing device which is made up of a plurality of image sensing units. In this prior art, the image sensing device is fixed to a robot arm, and is moved as instructed to sense images.
A conventional image sensing apparatus which allows the photographer to freely carry the image sensing apparatus main body and can analyze the shape of an arbitrary object will be described below.
FIG. 1
is a block diagram showing the arrangement of a conventional portable automatic image sensing apparatus and the principle of its use state.
In
FIG. 1
, reference numeral
1101
denotes an object to be sensed (a cup in this embodiment), which is placed on a pad
1102
, and a case will be explained below wherein this object
1101
is to be sensed. A plurality of bright point marks
1103
a
,
1103
b
, and
1103
c
are printed on the pad
1102
, and their position relationship is known and is pre-stored in an image sensing apparatus
1900
(to be described below).
Reference numeral
1900
denotes a portable image sensing apparatus, which comprises photographing lenses
1110
and
1111
, shutters
1112
and
1113
which also serve as iris diaphragms, image sensing elements
1114
and
1115
for performing photoelectric conversion, control circuits
1116
and
1117
for controlling the image sensing elements
1114
and
1115
, image signal processing circuits
1118
and
1119
for processing signals obtained from the image sensing elements
1114
and
1115
, image signal storage circuits
1120
and
1121
for storing image signals output from the image signal processing circuits
1118
and
1119
, a corresponding point extraction circuit
1122
, an image sensing parameter detection circuit
1123
, a ROM (read-only memory)
1124
that stores the (known) position relationship among the bright points on the pad, a unifying circuit
1125
for unifying three-dimensional information, and buffer circuits
1126
and
1127
for temporarily storing the three-dimensional information unified by the three-dimensional information unifying circuit
1125
.
This image sensing apparatus
1900
extracts corresponding points from the obtained two image signals by the corresponding point extraction circuit
1122
to obtain distance images at the individual timings, and at the same time, obtains image sensing parameters (the position relationship between the pad and the image sensing apparatus
1900
obtained based on the bright point coordinate positions, accurate focal length, and the like) using the image sensing parameter detection circuit
1123
and the ROM
1124
. The three-dimensional information unifying circuit
1125
calculates three-dimensional shape data and texture image data of the object
1101
on the basis of these distance images, image sensing parameters, and change information that expresses their time-series changes, and stores them in the buffer circuits
1126
and
1127
.
In
FIG. 1
, r
Iijima Katsumi
Ishikawa Motohiro
Katayama Tatsushi
Kurahashi Sunao
Matsugu Masakazu
Canon Kabushiki Kaisha
Chawan Sheela
Mehta Bhavesh M.
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