Projecting warped images onto curved surfaces

Details Projecting warped images onto curved surfaces Projecting warped images onto curved surfaces

2003-06-10

2004-09-21

Adams, Russell (Department: 2851)

Optics: image projectors

Methods

C353S094000, C353S069000, C353S122000, C382S154000, C702S152000

Reexamination Certificate

active

06793350

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to projecting images, and more particularly to projecting images onto curved surfaces.
BACKGROUND OF THE INVENTION
Projector systems have been used to render large images onto display surfaces. With multiple projectors, it is possible to generate even larger seamless displays. Such systems are particularly useful for constructing immersive visualization environments capable of presenting high-resolution images for entertainment, education, training, and scientific simulation. Known multi-projector technologies include Cruz-Neira et al., “
Surround
-
screen Projection
-
based Virtual Reality: The Design and Implementation of the CAVE
,” SIGGRAPH 93 Conference Proceedings, Vol. 27, pp. 135-142, 1993, Staadt et al., “
The blue
-
c: Integrating real humans into a networked immersive environment
,” ACM Collaborative Virtual Environments, 2000.
A number of techniques are known for generating seamless images on planar surfaces using electro-optical techniques to determine registration and blending parameters, see Li et al., “
Optical Blending for Multi
-
Projector Display Wall System
,” Proceedings of the 12
th
Lasers and Electro-Optics Society, 1999, or using a camera in a loop, Surati, “
Scalable Self
-
Calibrating Display Technology for Seamless Large
-
Scale Displays
,” Ph.D. Thesis, Massachusetts Institute of Technology, 1999, Chen et al., “
Automatic Alignment of High
-
Resolution Multi
-
Projector Displays Using An Un
-
Calibrated Camera
,” IEEE Visualization, 2000, and Yang et al, “
PixelFlex: A Reconfigurable Multi
-
Projector Display System
,” IEEE Visualization, 2001, Brown et al., “
A Practical and Flexible Large Format Display system
,” Tenth Pacific Conference on Computer Graphics and Applications, pp. 178-183, 2002, Humphreys et al., “
A Distributed Graphics System for Large Tiled Displays
,” IEEE Visualization, 1999, and Humphreys et al., “WireGL: A Scalable Graphics System for Clusters,” Proceedings of SIGGRAPH, 2001.
When multiple projectors are used, an accurate estimation of the geometric relationship between overlapping images is key for achieving a seamless display. The geometric relationship influences the rendering process and soft edge blending. Camera-based methods, which exploit a homography expressed by a 3 by 3 matrix, admit casually installed projectors while eliminating cumbersome manual alignment.
The relationship for surfaces that adhere to quadric equations can be defined using a quadric image transfer function, see Shashua et al., “
The quadric reference surface: Theory and applications
,” Tech. Rep. AIM-1448, 1994.
Multi-projector alignment for curved surfaces can be aided by projecting a ‘navigator’ pattern and then manually adjusting the position of the projectors. For a large scale display, such as used at the Hayden Planetarium in New York, it takes technicians several hours each day to align seven overlapping projectors.
One problem is that when 3D images are displayed on a curved screen, the images are perspectively correct from only a single point in space. This 3D location is known as the virtual viewpoint or ‘sweet-spot’. As the viewer moves away from the sweet-spot, the images appear distorted. For very large display screens and many view points, it is difficult to eliminate this distortion. However, in real-world applications, viewers would like to be at the exact same place where the projectors ideally need to be located. In addition, placing projectors at the sweet-spot means using a very wide-field of view projectors, which are expensive and tend to have excessive radial or ‘fish-eye’ distortion.
In another method, a non-parametric process places a camera at the sweet-spot. The camera acquires an image of a structured light pattern projected by the projector. Then, in a trial-and-error approach, samples are taken, to build an inverse warping function between a camera input image and a projected output image by means of interpolation. Then, the function is applied, and resampled until warping function correctly displays the output image, see Jarvis, “
Real Time
60
Hz Distortion Correction on a Silicon Graphics IG
,” Real Time Graphics 5, pp. 6-7, February 1997, and Raskar et al., “
Seamless Projection Overlaps Using Image Warping and Intensity Blending
,” Fourth International Conference on Virtual Systems and Multimedia, 1998.
It is desired to provide a parametric method for aligning multiple projectors that extends the homography-based approach for planar surfaces to quadric surfaces.
In computer vision, some work has been done on using quadric formulations for image transfer functions, see Shashua et al., above, and Cross et al., “
Quadric Surface Reconstruction from Dual
-
Space Geometry
,” Proceedings of 6
th
International Conference on Computer Vision, pp. 25-31, 1998. However, the linear methods intended for cameras, as described below, produce large errors when used with projectors, instead of cameras.
In multi-projector systems, several techniques are known for aligning images seamlessly on flat surfaces using planar homography relationships. However, there has been little work on techniques for parameterized warping and automatic registration of images displayed on higher order surfaces.
This is a serious omission because quadric surfaces do appear in many shapes and forms in projector-based displays. Large format flight simulators have traditionally been cylindrical or dome shaped, see Scott et al., “
Report of the IPS Technical Committee: Full
-
Dome Video Systems
,” The Planetarian, Vol. 28, p. 25-33, 1999, planetariums and OnmiMax theaters use hemispherical screens, Albin, “
Planetarium special effects: A classification of projection apparatus
,” The Planetarian, Vol. 23, pp. 12-14, 1994, and many virtual reality systems use a cylindrical shaped screen.
Therefore, it is desired to provide calibration methods, quadric transfer functions, and parametric intensity blending for images projected onto a curved display surface.
SUMMARY OF THE INVENTION
Curved display screens are increasingly being used for high-resolution immersive visualization environments. The invention provides a method and system for displaying seamless images on quadric surfaces, such as spherical or cylindrical surfaces, using a single or multiple overlapping projectors. A new quadric image transfer function is defined to achieve sub-pixel registration while interactively displaying two or three-dimensional images.


REFERENCES:
patent: 5319744 (1994-06-01), Kelly et al.
patent: 6104405 (2000-08-01), Idaszak et al.
patent: 6549651 (2003-04-01), Xiong et al.
patent: 2002/0059042 (2002-05-01), Kacyra et al.
Cruz-Neira et al., “Surround-screen Projection-based Virtual Reality: The Design and Implementation of the CAVE,”SIGGRAPH 93 Conference Proceedings, vol. 27, pp. 135-142, 1993.
Staadt et al., “The blue-c: Integrating real humans into a networked immersive environment,”ACM Collaborative Virtual Environments, 2000.
Chen et al., “Automatic Alignment of High-Resolution Multi-Projector Displays Using An Un-Calibrated Camera,”IEEE Visualization, 2000.
Yang et al, “PixelFlex: A Reconfigurable Multi-Projector Display System,”IEEE Visualization, 2001.
Humphreys et al., “A Distributed Graphics System for Large Tiled Displays,”IEEE Visualization, 1999.
Humphreys et al., “WireGL: A Scalable Graphics System for Clusters,”Proceedings of SIGGRAPH, 2001.
Raskar et al., “Seamless Projection Overlaps Using Image Warping and Intensity Blending,”Fourth International Conference on Virtual Systems and Multimedia, 1998.
Wexler and Shashua, “Q-warping: Direct Computation of Quadratic Reference Surfaces,”IEEE Conf. on Computer Vision and Pattern Recognition, CVPR, Jun., 1999.
Lu et al., “Fast and globally convergent pose estimation from video images,”IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 22:6, pp. 610-622, 2000.

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