Pseudo-random point sampling techniques in computer graphics

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that forms said frame, wherein the characteristic information of each pixel is determined by sampling, at a plurality of points within a boundary of each of said pixels, data stored in a computer data base that specifies visual characteristics of an object scene for said image frame, the improvement comprising the steps of electronically determining, for the sample points individually, a range of angles of rays extending from each such point to a source of illumination of the scene pseudo-randomly selecting one such angle for each such point, and determining for each of said selected rays whether other objects are in its path, whereby penumbras are shown in the image frame.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each an array of pixels that form said frame, wherein the characteristic information of each pixel is determined by sampling, at a plurality of points within a boundary of each of said pixels, data stored in a computer data base that specifies visual characteristics of an object scene for said image frame, the improvement comprising the steps of electronically determining, for the sample points individually, a range of angles of refraction of the object scene at such points, and pseudo-randomly selecting one such angle for each such sample point, whereby other portions of the object scene that are visible by transparency through a sample point of the object scene are determined.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that form said frame, wherein the characteristic information of each pixel is determined by sampling at at least one point within a boundary of each of said pixels, data stored in a computer data base that specifies spatial locations and the visual characteristics of objects in a scene for said image frame, the improvement comprising electronically positioning said sample points in a spatial distribution across said frame such that a Fourier transform of such a distribution over an infinite extent is substantially continuous in some regions and establishing the characteristics of an optical imaging system, including aperture size and focal plane relative to the objects of the scene, and determining the characteristics of the objects for each sample by taking into account the distance of the objects from the focal plane and the size of the lens aperture, whereby the image frame electronic signal contains information of the objects within a certain depth of field as determined by the characteristics of the optical imaging system.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each an array of adjacent areas that forms said frame, wherein the characteristic information of each such array is determined by sampling, at a plurality of points in a certain pattern within a boundary of substantially every area across said image frame, data stored in a computer data base that specifies spatial locations and visual characteristics of an object scene for said image frame, the improvement comprising electronically arranging said plurality of sample points within substantially every such area in a spatial distribution therein such that a Fourier transform of such a distribution over an infinite extent has substantially continuous in some regions, and establishing the characteristics of an optical imaging system, including aperture size and focal plane relative to the objects of the scene, and determining the characteristics of the objects for each sample by taking into account the distance of the objects from the focal plane and the size of the lens aperture, whereby the image frame electronic signal contains information of the objects within a certain depth of field as determined characteristics of the optical imaging system.

A method for point sampling image data in a computer system for determining characteristic information of pixels comprising said image data, said method comprising the steps of:

• selecting a plurality of sample regions comprising at least a portion of a pixel;
• selecting sample points within said regions such that the distribution of sample points of the smallest sample region is nonperiodic, and;
• combining the characteristic information of the sample points in each pixel, thereby to determine a single characteristic information of each pixel.

A method for point sampling image data in a computer system for determining characteristic information of pixels comprising said image data, said method comprising the steps of:

• selecting a plurality of sample regions comprising at least a portion of a pixel, and;
• selecting sample points within said regions such that the distribution of sample points of the smallest sample region is nonrectangular and nonrectilinear.

A method for point sampling image data in a computer system for determining characteristic information of pixels comprising said image data, said method comprising the steps of:

• defining a sample region comprising at least a portion of said one of said pixels;
• defining a grid pattern wherein a first number of regularly spaced sample point locations are defined in said sample region, and;
• point sampling at a second number of selected sample point locations of said grid pattern, said second number being less than said first number, said selected sample point locations disposed in a nonregular distribution in said grid pattern.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of adjacent areas that form said frame, wherein the characteristic information of such area is determined by sampling at a plurality of points in a certain pattern within a boundary of substantially every such area across said image frame, data stored in a computer data base that specifies spatial locations and visual characteristics of an object scene for said image frame, the improvement comprising the steps of electronically defining a plurality of substantially nonoverlapping portions within such area and then locating each sample point within an individual area portion pursuant to a nonregular distribution.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that forms said frame, wherein the characteristic information of each pixel is determined by point sampling at at least one point within a boundary of each of said pixels, data stored in a computer data base that spacifies various parameters relating to an object scene, the improvement wherein the sampling is electronically accomplished by a pseudo-random distribution of at least one of said stored parameters such that a Fourier transform of such a distribution over an infinite extent contains substantially continuous regions, said at least one stored parameters including location of objects in the scene relative to the image frame.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that forms said frame, wherein the characteristic information of each pixel is determined by sampling at least one point within a boundary of each of said pixels, data stored in a computer data base that specifies spatial locations and visual characteristics of objects in a scene for said image frame, the improvement comprising electronically positioning said sample points in a spatial distribution across said frame such that a Fourier transform of such a distribution of over an infinite plane is substantially continuous in some regions, and said improvement additionally comprises locating a plurality of sample points within each pixel and wherein said computer data base contains information of spatial movement of the objects during a time period represented by said image frame, and further wherein the characteristic information of the objects is determined for each of the plurality of sample points within each pixel at one of a plurality of different instants during said image frame time period, thereby to show any motion blur of the object scene in the resulting image frame electronic signal.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of adjacent areas that forms said frame, wherein the characteristic information of each such area is determined by sampling, at a plurality of points in a certain pattern within a boundary of substantially every such area across said image frame, data stored in a computer data base that specifies spatial locations and visual characteristics of an object scene for said image frame, the improvement comprising electronically arranging said plurality of sample points within substantially every such area in a spatial distribution therein such that a Fourier transform of such a distribution over an infinite plane is substantially continuous in some regions, wherein said electronic information of spatial movement of the object scene during a time period represented by said image frame, and further wherein the characteristic information of the object is determined for each of the plurality of sample points within each frame area at one of a plurality of different instants during said image frame time period, thereby to show any motion blur of the object scene that occurs during the time period of said image frame.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that forms said frame, wherein the characteristic information of each pixel is determined by sampling, at a plurality of points within a boundary of each of said pixels, data stored in a computer data base that specifies visual characteristics of an object scene for said image frame, the improvement comprising the steps of including in said computer data base information of changes in the object scene visual characteristics that occur during the time period of said image frame, and electronically sampling the data base at said plurality of points at different instants during said time period, whereby any motion blur of the object scene is included in the resulting image frame electronic signal, wherein the steps of sampling the data base at said plurality of points includes doing so pseudo-randomly as a function of time for each such pixel and within said time period of said image frame, whereby the image frame signal has reduced aliasing in time.

In a method of forming an electronic signal of a video image frame that individually specifies characteristic information of each of an array of pixels that forms said frame, wherein the characteristic information of each pixel is determined by sampling, at a plurality of points within a boundary of each of said pixels, data stored in a computer data base that specifies visual characteristics of an object scene for said image frame, the improvement comprising the steps of establishing the characteristics of an optical imaging system, including aperture size and focal plane relative to the objects of the scene, and electronically determining the visual characteristics of the object scene at each point sample by taking into account the distance of the objects from the focal plane and the size of the lens aperture, whereby the image frame electronic signal contains information of the objects with a certain depth of field as determined by the characteristics of the optical imaging system, wherein the step of determining the visual characteristics of the object scene for each point sample includes pseudo-randomly determining the point on the lens from which the object scene is sampled within a field of vie of the object scene that is determined by the lens aperture and location of the focal plane.