Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
2001-07-03
2004-06-01
Bella, Matthew C. (Department: 2676)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S587000, C345S589000, C345S597000, C345S598000, C345S629000
Reexamination Certificate
active
06744441
ABSTRACT:
BACKGROUND OF THE INVENTION
In general, the present invention relates to a three-dimensional-picture-generating apparatus, a three-dimensional-picture-generating method and a program-presenting medium with regard to texture picture pasting techniques for three-dimentionally-shaped model. More particularly, the present invention relates to a three-dimensional-picture-generating apparatus and a three-dimensional-picture-generating method that are capable of generating a real three-dimensional picture with little unnaturalness by improving processing to paste texture pictures each taken at a virtual point of sight.
There are known measurement techniques applied to an object having a three-dimensional shape which is treated as an object of measurement. The measurement techniques include a method whereby a beam is radiated by a beam source to the object of measurement and a time it takes till a beam reflected by the object reaches the source is measured. In another measurement technique, a pattern beam having a slit shape is radiated to an object of measurement and the shape of the pattern beam projected on the object of measurement is inspected. In accordance with a further measurement technique known as a stereo picture method for measuring a distance, at least 2 cameras are used and a corresponding point between their pictures is identified to find a parallax in a measurement of a distance.
A picture reflecting actual colors of a measurement object is pasted on a three-dimensional model representing the measurement object's distance data obtained as a result of measurements using a variety of such methods to generate a real three-dimensional picture. An actual picture of the measurement object is called a texture picture. A process of pasting a texture picture on a three-dimensional shape is referred to as texture mapping.
In general, a picture pasted on a surface of a three-dimensional model is a two-dimensional bit-map picture or an image-file picture. A texture picture comprising a two-dimensional bit-map picture and an image-file picture is pasted and combined on a surface of a three-dimensionally-shaped model created by using a three-dimensional graphic technique or a surface of a substance's three-dimensional shape obtained by using a three-dimensional-shape measurement apparatus to display a three-dimensional substance. By pasting the picture of bricks on such a surface, for example, a natural three-dimensional wall can be expressed. By pasting a picture of a world map on a spherical body, a cubic earth can be expressed.
FIG. 1
is an explanatory diagram showing a general texture-mapping technique. A three-dimensionally-shaped model
101
shown in the figure is a model based on distance data obtained as a result of measurements using typically the stereo picture method described above or the like. A two-dimensional picture (a texture)
102
is a real picture reflecting visual-sense color data or the like obtained as a result of photographing from a certain point of vision. Texture mapping is a process of pasting the two-dimensional picture (the texture)
102
on the three-dimensionally-shaped model
101
. By carrying out the texture-mapping process, a real three-dimensional expression is possible. It should be noted that a wire-frame display shown in the figure shows a planar area on which the texture obtained from the three-dimensionally-shaped model
101
is pasted.
So far, there have been studied a variety of technologies for pasting a texture picture on a substance's three-dimensional shape obtained by adoption of the stereo picture method or by using a three-dimensional measurement apparatus utilizing both a laser beam and a projection beam or the like. Assume that texture pictures seen from a plurality of visual points are pasted on corresponding areas of a measurement object. In this case, if the texture pictures are taken under different beam-source conditions, there will be differences in color tone among the texture pictures. The differences in color tone are caused by differences in beam-source condition which prevail when the texture pictures are taken individually. The differences in color tone result in an unnatural combination of colors in a picture if the resulting picture is produced by merely pasting the texture pictures. In order to solve this problem, there is provided a texture-mapping technique to produce a higher picture quality whereby beam-source conditions under which the texture pictures are taken are estimated, and the texture pictures are compensated for the differences in color tone on the basis of a result of the estimation. An example of such a technique is described in a reference authored by Imari Satoh, Youichi Satoh and Katsumi Ikeuchi with a title of “All-Azimuth Measurements of Beam-Source Environments and Superposition of Real Pictures on a Virtual Substance Based on Results of the Measurements,” a thesis of the Academic Society of Electronic, Information and Communication Engineers D-II, Vol. J81-D-II, No. 5, pp. 861-871, 1998.
When a picture of outdoor scenery or a building is taken by using an apparatus such as a digital still camera or a digital video camera in general, however, the condition of a source radiating a beam is not easy to estimate. It is thus difficult to implement texture mapping to produce a high picture quality by using a plurality of taken pictures, that is, a plurality of texture pictures. In order to avoid unnaturalness caused by use of a plurality of texture pictures, for example, there is also provided a texture-mapping technique using only one texture picture as shown in FIG.
2
.
FIG. 2
is a diagram showing a configuration for implementing a texture-mapping process by pasting a particular picture of a proper area of a two-dimensional picture (texture picture)
202
on a wire frame of a three-dimensionally-shaped model
201
.
With a technique of using only 1 particular picture as described above, however, there is raised a problem of a deteriorating texture picture quality caused by a change in point of vision. Assume for example that the acquired two-dimensional picture (texture picture)
202
is based on the picture of the front surface
203
of a cup shown in FIG.
2
and an end
204
thereof. In this case, there will be resulted in a difference in picture quality between the front surface
303
and the end
204
of the cup. This difference in picture quality causes deterioration of the picture quality.
As a technique of solving the deterioration of the picture quality described above, there is provided a method of selecting a texture picture taken from a photographing visual point closest to the virtual point of view and pasting the selected texture picture on a three-dimensionally-shaped model. This method is described by referring to FIG.
3
. In the method shown in
FIG. 3
, a texture picture of a measurement object
301
is taken from a plurality of visual points, namely, photographing visual points 1 to n. If a virtual point of vision is set, a photographing visual point closest to the virtual visual point is selected, and a texture picture taken from the selected photographing visual point is pasted on a three-dimensionally-shaped model of the measurement object
301
. In the example shown in
FIG. 3
, the RGB values of a virtual visual point are used as those of the photographing visual point
1
or
2
. Notation &thgr;1 denotes an angle formed by directions from the virtual visual point and the photographing visual point
1
, whereas notation &thgr;2 denotes an angle formed by directions from the virtual visual point and the photographing visual point
2
. If &thgr;1<&thgr;2, the RGB values of the photographing visual point
1
are selected. If &thgr;1>&thgr;2, on the other hand, the RGB values of the photographing visual point
2
are selected. By adopting this method, the picture quality is improved. With this method, however, it is difficult to maintain concentration contiguity between pictures and, if the point of vision changes, unnaturalness of the picture results.
Sato Hiroyuki
Wu Weiguo
Yokoyama Atsushi
Bella Matthew C.
Rahmjoo Manucher
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