Method and apparatus for imaging volume data using voxel values

• US 5,381,518 A
• Filed: 12/18/1992
• Issued: 01/10/1995
• Est. Priority Date: 04/14/1986
• Status: Expired due to Fees

• Current Assignee: Pixar (The Walt Disney Company)
• Original Assignee: Pixar (The Walt Disney Company)
• Inventors: Drebin, Robert A., Carpenter, Loren C.
• Primary Examiner(s): Bayerl, Raymond J.
• Application Number:
  US07/993,830
• Time in Patent Office: 753 Days
• Field of Search: 395/124, 395/121, 395/135, 395/131, 395/163, 364/413.19, 364/413.22, 364/413.16, 364/413.18
• US Class Current: 345/424
• CPC Class Codes: G06T 17/00 Three dimensional [3D] modelling, e.g. data description of 3D objects

Abstract

An imaging system for providing apparatus and method for projecting a two dimensional (2D) representation of three dimensional (3D) volumes where surface boundaries and objects internal to the volumes are readily shown, and hidden surfaces and the surface boundaries themselves are accurately rendered. In the present invention, the two dimensional image produced is capable of having the same resolution as the sampling resolution of the input image image volume of interest. This is accomplished through the implementation of methods for determining "partial volumes" of voxels. Partial voluming provides for the assignment of selected colors and opacities to different materials (or data components) represented in an image data volume based on the percentage composition of materials represented in each voxel of the image volume. Unlike prior art systems, such as those that use thresholding techniques, the imaging of the present invention has a high degree of precision and definition that is independent of image volume on a per voxel basis.

Claims

1. A method of generating a two dimensional representation of a three dimensional data set along a selected orientation of view comprising the steps of:

generating a first image volume representing said three dimensional data set;

storing said first image volume in a first image memory comprising a plurality of volume elements (voxels);

generating a new background plane of voxels of said image volume by combining in a host computer a background plane of voxels of said image volume with a foreground plane of voxels of said image volume along a selected orientation of view, said new background plane of voxels having color and opacity values determined as a function of the color and opacity of the background plane of voxels and the foreground plane of voxels, wherein said function is given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said new background plane;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels;

successively repeating in said host computer the prior step for each new background plane of voxels and successive foreground plane of voxels through an nth foreground plane of voxels where n represents the total number of said foreground planes of voxels.

2. An apparatus for generating a two dimensional display of a three dimensional data set comprising:

first storage means coupled to an image generating means for storing an image volume as a plurality of homogeneous arrays each said array comprising a plurality of volume elements (voxels);

a host computer including processing means coupled to said first storage means for assigning a color value and an opacity value to each voxel to create a second image volume;

second storage means coupled to said processing means for storing said second image volume;

said host computer including combining means coupled to said second storage means for successively combining a background plane of voxels and a foreground plane of voxels to generate a new background plane of voxels having color and opacity values that are a function of the color and opacity values of the background plane of voxels and foreground plane of voxels, wherein said function is given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said new background plane;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels.

3. An apparatus for generating a two dimensional display of a three dimensional data set comprising:

image generating means for generating a first image volume representing said three dimensional data set;

first storage means coupled to said image generating means for storing said image volume as a plurality of homogeneous arrays, each of said arrays comprising a plurality of scan lines having a plurality of volume elements (voxels);

a host computer including processing means coupled to said first storage means for assigning a color and opacity value to each voxel to create a second image volume;

second storage means coupled to said processing means for storing said second image volume;

said host computer including combining means coupled to said second storage means for combining all voxels of one of said scan lines with all voxels of a next consecutive of said scan lines along a selected view path to produce a combination image volume comprising voxels having color and opacity values based on a function of the color and opacity values of voxels in previously combined scan lines;

display means coupled to said combining means for displaying said combination image volume; and

said function is given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels.

4. The apparatus of claim 3 wherein said processing means comprises a host computer.

5. The apparatus of claim 3 wherein said combining means comprises a plurality of parallel processors.

6. The apparatus of claim 5 wherein said plurality of parallel processors comprises 4.

7. The apparatus of claim 6 wherein said color value comprises red components, green components and blue components.

8. The apparatus of claim 7 wherein said red, green and blue components and said opacity value of a voxel are combined with said red, green and blue components and said opacity value of another voxel in the first, second, third and fourth channels of said four parallel processors respectively.

9. An apparatus for generating a two dimensional display of a three dimensional data set comprising:

image generating means for generating a first image volume representing said three dimensional data set;

first storage means coupled to said image generating means for storing said image volume as a plurality of homogeneous arrays, each of said arrays comprising a plurality of scan lines having a plurality of volume elements (voxels);

processing means coupled to said first storage means for assigning a color and opacity value to each voxel to create a second image volume;

second storage means coupled to said processing means for storing said second image volume;

combining means comprising a plurality of parallel processors coupled to said second storage means for combining one of said scan lines with a next consecutive of said scan lines along a selected view path to produce a combination image volume comprising voxels having color and opacity values based on a function of the color and opacity values of voxels in previously combined scan lines;

display means coupled to said combining means for displaying said combination image volume; and

said function is given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels.

10. The apparatus of claim 9 wherein said plurality of parallel processors comprises 4.

11. The apparatus of claim 10 wherein said color value comprises red, green and blue components.

12. The apparatus of claim 11 wherein said red, green and blue components and said opacity value of a voxel are combined with said red, green and blue components and said opacity value of another voxel in the first, second, third and fourth channels of said four parallel processors, respectively.

13. A method of generating a two dimensional representation of a three dimensional data set comprising the steps of:

generating a first image volume, said first image volume representing said three dimensional data set;

storing said first image volume in a first image memory as a plurality of homogeneous storage arrays, each array comprising a plurality of scan lines having a plurality of volume elements (voxels);

assigning each voxel a color value and an opacity value;

for each scan line of each of said arrays, generating a combination image volume in a host computer by combining all voxels of one of said scan lines with all voxels of a next consecutive of said scan lines along a selected view path;

repeating in said host computer the prior step for each consecutive of said scan lines with each previously generated combination image volume through an nth scan line where n represents the total number of said scan lines;

said combination image volume having voxels whose color and opacity values are determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a voxel of one of said scan lines;

A=the opacity of said voxel of one of said scan lines; and

BG=the composite color and opacity components of the corresponding voxel in previously combined scan lines.

14. A method of generating a combination volume element (voxel) representative of a plurality of adjacent voxels viewed from a selected orientation comprising the steps of:

assigning to each voxel a color value and an opacity value;

storing each voxel in a first storage means;

generating a combination voxel by combining in a host computer one of said plurality of adjacent voxels along a selected view path with a next consecutive of said plurality of voxels along said selected view path such that said combination voxel has a color and opacity value determined as a function of said color and opacity of said one voxel and said next consecutive voxel;

successively repeating in said host computer the prior step for each next consecutive of said voxels such that each successive combination voxel has color and opacity values determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel; and

BG=the color and opacity components of previously combined voxels.

15. An apparatus for generating a two dimensional display of a three dimensional data set comprising:

image generating means for generating a first image volume representing said three dimensional data set;

first storage means coupled to said image generating means for storing said image volume as a plurality of homogeneous arrays, each of said arrays comprising a plurality of scan lines having a plurality of volume elements (voxels);

a host computer coupled to said first storage means for assigning a color and opacity value to each voxel to create a second image volume;

second storage means coup ted to said host computer for storing said second image volume;

combining means coupled to said second storage means for combining all voxels of one of said scan lines with all voxels of a next consecutive of said scan lines along a selected view path to produce a combination image volume comprising voxels having color and opacity values determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels; and

display means coupled to said combining means for displaying said combination image volume.

16. A method of generating a volume element (voxel) representative of a combination of voxels in an image volume along a selected orientation of view, each voxel having a color and opacity value, comprising the steps of:

providing a background voxel along a selected orientation of view;

providing a foreground voxel adjacent to said background voxel along said selected orientation of view;

storing said background voxel and said foreground voxel in a storage means;

generating a new background voxel by combining in a host computer said background voxel and said foreground voxel such that said new background voxel has a color value and an opacity value given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of said new background voxel;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel; and

BG=the color and opacity components of previously combined voxels.

17. A method for rendering a two dimensional representation of a three dimensional data set from a selected orientation of view comprising the steps of:

generating an image volume comprised of voxels, each said voxel having a color value and an opacity value representative of data in said three dimensional data set;

storing said image volume in a storage means;

determining the color and opacity of pixels in a two dimensional projection plane, said projection plane representing a desired plane of view of said image volume, by successively combining in a host computer voxels of said image volume behind said projection plane performed for said voxels along a line of selected orientation of view successively toward said projection plane associated with each said pixel in said projection plane;

said color and opacity of each successively combined voxel is given by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of said each successively combined voxel;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel; and

BG=the color and opacity components of previously combined voxels.

18. A method for generating a two dimensional representation of a three dimensional data set from a selected orientation of view comprising the steps of:

determining the color and opacity of adjacent planes of voxels stored in a storage means associated with said three dimensional data set for said selected orientation of view, said planes of voxels being substantially perpendicular to the selected orientation of view;

determining the color and opacity of pixels in a two dimensional projection plane representing a selected plane of view of said image volume, by successively combining in a host computer said planes of voxels of said image volume behind said projection plane along said selected orientation of view;

the color and opacity of each combined plane of voxels being determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said each combined plane;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel; and

BG=the color and opacity components of previously combined voxels.

19. A method of generating a two dimensional representation of a three dimensional data set along a selected orientation of view comprising the steps of:

generating a first image volume representing said three dimensional data set;

storing said first image volume in a first image memory comprising a plurality of volume elements (voxels);

generating a new background plane of voxels of said image volume by combining in a host computer a background plane of voxels of said image volume with a foreground plane of voxels of said image volume along a selected orientation of view, said new background plane of voxels having color and opacity values determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said each new background plane;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels; and

successively repeating the prior step for each new background plane of voxels and successive foreground plane of voxels through an nth foreground plane of voxels where n represents the total number of said foreground planes of voxels.

20. An apparatus for generating a two dimensional display of a three dimensional data set, comprising;

first storage means coupled to an image generating means for storing an image volume as a plurality of homogeneous arrays each said array comprising a plurality of volume elements (voxels);

a host computer including processing means coupled to said first storage means for assigning a color value and an opacity value to each voxel to create a second image volume;

second storage means coupled to said processing means for storing said second image volume;

said host computer including combining means coupled to said second storage means for generating a combination image volume by successively combining a background plane of voxels and a foreground plane of voxels to generate a new background plane of voxels having color and opacity values that are determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG) (A)) (BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxel; and

display means coupled to said combining means for displaying said combination image volume.

21. An apparatus for generating a two dimensional display of a three dimensional data set comprising:

image generating means for generating a first image volume representing said three dimensional data set;

first storage means coupled to said image generating means for storing said image volume as a plurality of homogeneous arrays, each of said arrays comprising a plurality of scan lines having a plurality of volume elements (voxels);

processing means coupled to said first storage means for assigning a color and opacity value to each voxel to create a second image volume;

second storage means coupled to said processing means for storing said second image volume;

combining means comprising a plurality of parallel processors coupled to said second storage means for combining one of said scan lines with a next consecutive of said scan lines along a selected view path to produce a combination image volume comprising voxels having color and opacity values determined by;

space="preserve" listing-type="equation">BG'"'"'=FG+(1-(FG)(A))(BG)

where;

BG'"'"'=the color and opacity components of the corresponding voxel in said combination image volume;

FG=the color and opacity components of a selected voxel;

A=the opacity of said selected voxel;

BG=the color and opacity components of previously combined voxels; and

display means coupled to said combining means for displaying said combination image volume.