Multi-planar volumetric display system and method of operation using three-dimensional anti-aliasing

• US 6,377,229 B1
• Filed: 04/14/1999
• Issued: 04/23/2002
• Est. Priority Date: 04/20/1998
• Status: Expired due to Term

• Current Assignee: Lightspace Technologies, Inc. (LC-Tec Holding AB)
• Original Assignee: Dimensional Media Associates, Inc.
• Inventors: Sullivan, Alan
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Eisen, Alexander
• Application Number:
  US09/291,315
• Time in Patent Office: 1,105 Days
• Field of Search: 345/4-6, 345/419, 345/422, 345/424, 345/427, 345/431, 345/433, 345/439, 345/434, 345/136, 345/137, 345/7-9, 345/611, 345/614, 348/744, 359/443, 359/462
• US Class Current: 345/6
• CPC Class Codes: G02B 30/52 the 3D volume being constructed from a stack or sequence of 2D planes, e.g. depth sampling systems
• CPC Class Codes: G06T 15/00 3D [Three Dimensional] image rendering
• CPC Class Codes: G09G 3/003 to produce spatial visual effects
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 13/388 Volumetric displays, i.e. systems where the image is built up from picture elements distributed through a volume
• CPC Class Codes: H04N 13/395 with depth sampling, i.e. the volume being constructed from a stack or sequence of 2D image planes
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

A multi-planar volumetric display system and method of operation generate volumetric three-dimensional images using a multi-surface optical device including a plurality of individual optical elements arranged in an array; an image projector for selectively projecting images on respective optical elements to generate a first volumetric three-dimensional image viewable in the multi-surface optical device; and a floating-image generator for projecting the first volumetric three-dimensional image to generate a second volumetric three-dimensional image viewable as floating in space at a location separate from the multi-surface optical device. Anti-aliasing adjusts the display of voxels in a transition between optical elements, such that color values of the voxels are modified as a function of the distance of the voxels from the optical elements, to generate a smooth transition between portions of the volumetric three-dimensional image.

Claims

1. A method for performing anti-aliasing of a first voxel of a three-dimensional image displayed on a plurality of optical elements, wherein a first voxel depth value of the first voxel is between a pair of optical element depth values corresponding to a pair of optical elements bounding the first voxel, the method comprising the steps of:

generating a depth adjustment value from the first voxel depth value;

adjusting a first color value associated with the first voxel using the depth adjustment value; and

displaying a second voxel on at least one of the pair of optical elements using the adjusted color value.

2. The method of claim 1, further comprising the step of:

scaling the first voxel depth value to be within a predetermined range of indices associated with the plurality of optical elements; and

wherein the step of generating the depth adjustment value includes the step of generating the depth adjustment value from the scaled voxel depth value.

3. The method of claim 2, wherein the step of generating the depth adjustment value includes the step of:

determining a fractional portion of the scaled voxel depth value to be the depth adjustment value.

4. The method of claim 3, wherein the step of adjusting the first color value includes the step of:

multiplying the first color value by a function of the fractional portion to generate a second color value as the adjusted color value, with the second color value being associated with the second voxel.

5. The method of claim 1, further including the step of:

modifying the depth adjustment value with an anti-aliasing parameter to control the degree of anti-aliasing of the three-dimensional image.

6. The method of claim 1, wherein the step of adjusting the first color value includes the step of generating second and third color values from the first color value using the depth adjustment value;

and

wherein the step of displaying the second voxel includes the step of;

displaying the second voxel and a third voxel on a respective one of the pair of optical elements using the second and third color values, respectively.

7. The method of claim 6, wherein the plurality of optical elements are uniformly spaced.

8. The method of claim 6, wherein the plurality of optical elements are not uniformly spaced.

9. The method of claim 6, wherein the plurality of optical elements have variable spacings therebetween.

10. The method of claim 9, further comprising

searching through a plurality of depth values associated with the plurality of optical elements to determine a pair of optical elements wherein the first voxel depth value is between the depth values associated with the pair of optical elements.

11. The method of claim 6, wherein the step of generating the depth adjustment value includes the step of:

generating the depth adjustment value from the first voxel depth value and the optical element depth values associated with the voxel and the pair of optical elements, respectively.

12. The method of claim 11, wherein the depth adjustment value λ

is calculated according to;

$\mathrm{\lambda <br><br>}=<br><br>\frac{D_V-D_{\mathrm{NEAR1}}}{D_{\mathrm{NEAR1}}-D_{\mathrm{NEAR2}}}<br><br>,$

where D_V represents the first voxel depth value, and D_NEAR1 and D_NEAR2 represent optical element depth values that satisfy the condition D_NEAR1≦

D_V≦

D_NEAR2.

13. The method of claim 1, wherein said depth adjustment value is generated according to a function provided by software that is used to render images having a three-dimensional appearance on a two-dimensional display.

14. The method of claim 13, wherein said software comprises the OpenGL application programming interface and said function comprises a fog function provided therein.

15. The method of claim 14, wherein said function comprises a combination of said fog functions.

16. A system for generating volumetric three-dimensional images, the system comprising:

a multi-surface optical device including a plurality of individual optical elements; and

a controller for anti-aliasing of image data including voxels having depth values between the depth values of the optical elements to generate image slices having processed voxels with adjusted color values; and

an image projector for selectively projecting the image slices on respective optical elements of the multi-surface optical device to generate a volumetric three-dimensional image.

17. The system of claim 16, further comprising:

a floating-image generator for projecting the first volumetric three-dimensional image from the multi-surface optical device to generate a second volumetric three-dimensional image viewable as floating in space at a location separate from the multi-surface optical device.

18. The system of claim 16, wherein each of the plurality of individual optical elements of the multi-surface optical device includes a liquid crystal element having a controllable variable translucency to receive the anti-aliased images.

19. The system of claim 18, further comprising:

an optical element controller for controlling the translucency of the liquid crystal elements wherein;

a single liquid crystal element is controlled to have an opaque light-scattering state to receive and display the respective one of the set of anti-aliased images from the image projector; and

the remaining liquid crystal elements are controlled to be substantially transparent to allow the viewing of the displayed image on the opaque liquid crystal element.

20. A method for generating a volumetric three-dimensional image having a smoothed depth appearance on a plurality of optical elements having depth values associated with depth values of said image, comprising the steps of:

providing image data representative of said three-dimensional image, including voxels thereof having depth values that do not correspond to the depth values of the plurality of the optical elements;

anti-aliasing said image data by processing said voxels to produce anti-aliased image data; and

selectively projecting slices of the anti-aliased image data including said processed voxels onto the plurality of optical elements to generate said volumetric three-dimensional image.

21. The method of claim 20, wherein said voxels are processed to generate depth adjustment values for one or more of said voxels.

22. The method of claim 21, wherein the depth adjustment value for each one or more of said voxels is generated as a function of the distance of said voxel from at least one of the optical elements.

23. The method of claim 22, wherein the depth adjustment value λ

is calculated according to;

$\mathrm{\lambda <br><br>}=<br><br>\frac{D_V-D_{\mathrm{NEAR1}}}{D_{\mathrm{NEAR1}}-D_{\mathrm{NEAR2}}}<br><br>,$

where D_V represents the voxel depth value, and D_NEAR1 and D_NEAR2 represent optical element depth values that satisfy the condition D_NEAR1≦

D_V≦

D_NEAR2.

24. The method of claim 21, wherein the depth adjustment value of a voxel is used to modify its color value to generate one or more processed voxels each having a modified color value for selective projection on at least one of the optical elements.

25. The method of claim 24, wherein one of the modified color values is obtained by multiplying the color value of the voxel by its depth adjustment value λ

.

26. The method of claim 24, wherein one of the modified color values is obtained by multiplying the color value of the voxel by the quantity (1−

λ

).

27. The method of claim 24, wherein the color value specifies at least the brightness of a voxel.

28. The method of claim 24, wherein the depth adjustment value is divided by an anti-aliasing parameter P to control the degree of anti-aliasing.

29. The method of claim 28, wherein the modified color value of at least one of said processed voxels is determined by multiplying the color value of said voxel by λ

/P.

30. The method of claim 28, wherein the modified color value of at least one of said processed voxels is determined by multiplying the color value of said voxel by (1−

λ

/P).

31. The method of claims 29 or 30 wherein said one or more processed voxels are selectively projected only if their modified color values exceed a predetermined threshold.

32. The method of claim 20, further comprising the step of projecting the anti-aliased volumetric three-dimensional image formed on the plurality of optical elements to generate a second volumetric three-dimensional image viewable as floating in space at a location separate from the plurality of optical elements.

33. The method of claim 20, further comprising the step of controlling the translucency of each of the plurality of individual optical elements using an optical element controller to respectively receive and display the selectively projected processed voxels.

34. The method of claim 33, wherein the controlling step comprises the steps of:

causing a single optical element to have an opaque light-scattering state to receive and display the selectively projected processed voxels; and

causing the remaining optical elements to allow the selectively projected processed voxels to be transparent.

35. The method of claim 33, wherein the optical elements comprise liquid crystal elements.

36. The method of claim 22, wherein said depth adjustment value is generated according to a function provided by software that is used to render images having a three-dimensional appearance on a two-dimensional display.

37. The method of claim 36, wherein said software comprises the OpenGL application programming interface and said function comprises a fog function provided therein.

38. The method of claim 37, wherein said function comprises a combination of said fog functions.