Other

Massachusetts Institute of Technology

Che-Chih Tsao

Emanuel Michael Sachs

Zhen-Hong Zhou

Albert K Hu

The volumetric 3D display system of this invention applies a moving display panel that sweeps a display space. The full volume swept by the active screen is used as display space. A 3D image to be displayed is first processed into slices of image data based on an orthogonal 3D grid structure. The slice data are then converted into image frames to be displayed on the active screen by mapping the location indices in the orthogonal 3D grid to the location indices on the moving screen. The preferred method of displaying an image frame is to convert each image frame into a number of 'image shots' and then display those image shots in sequence. An image shot comprises a number of simple orthogonal patterns aligned in vertical or horizontal directions. Combination of a number of image shots approximates the corresponding image frame.

Active screen volumetric 3D display

This invention relates in general to methods and systems of rapid focusing and zooming for the applications in the projection of volumetric 3D images and in the imaging of 3D objects. Rapid variable focusing or zooming is achieved by rapid and repeated change of the object distance or the spacing between lens groups of the projection lens or a combination of both. One preferred approach inserts thin wedge prisms into the optical path and changes their positions relative to the optical path. This changes the thickness traveled through by the optical path and results in effective optical path length change. Another approach folds an optical path by mirrors and moves the mirrors to change the optical path length. For focusing purpose, small and precise displacement is achieved by moving a wedge-shaped optical device obliquely with respect to the optical path. The wedge-shaped optical device can be a thin wedge prism or a mirror on a wedge-shaped base. Optical layout analysis shows that the changes of the object distance, of the spacing between two lens groups and of the image distance are almost in proportion and can be correlated by linear relations. Therefore, the same type of motion function can be used to change these three optical path lengths to achieve focusing and constant magnification.

Methods and systems of rapid focusing and zooming for volumetric 3D displays and cameras

This invention describes methods of displaying both physiological and psychological depth cues in a volumetric image display. This added psychological visual depth can display a background image of infinite depth. The basic concept is to combine a skewed coordinate system with a 2D image plane and display the V3D object as a V3D image according to the skewed 3D coordinates if the object falls in the physical 3D space, but display the object as a 2D perspective image if it falls beyond the 3D space into the 2D plane's virtual space.

Methods of displaying volumetric 3D images

This invention describes procedures for writing data to a spatial light modulator (SLM) to achieve the purpose of 'sub-frame method', i.e. increasing effective frame rate of the SLM, without the need of additional color switching means or modulation at illumination source. The purpose is to improve the resolution of V3D displays based on projectors. The method divides the pixels of the SLM into a number of groups and defines each group as a sub-panel. Frames of image data are then written in sequence to each of the sub-panels in a fixed order. An image frame written to a sub-panel is called a 'sub-frame' when displayed on the sub-panel. The method then displays one sub-frame on one sub-panel at a time, with the rest sub-panels displaying blank (black). If the SLM has no memory buffer and image is displayed when it is written, then all data on the SLM must be erased after a sub-panel is being displayed and before the next sub-panel is written. If the SLM has a memory buffer and to update the SLM with the written data requires a separate command, then one can erase the data of previous sub-panel after the next sub-panel is written and is ready to display.

Data writing methods for volumetric 3D displays

The fundamental concept of expressing brightness level of a geometric primitive is to control the number of rendered display elements, representing desired brightness level, in the geometric primitive as a fraction of the maximum number of display elements, representing the maximum brightness level, that can be placed in it. There are two approaches to achieve this control: Point-based Rendering and Intersection-based Rendering. In Point-based Rendering, a geometric primitive is converted into a representation of sampling points and then the sampling points are rendered. In Intersection-based Rendering, the intersections of a geometric primitive with the frame slices are rendered. The basic procedure to render a texture-mapped surface is to divide the surface into a number of regions, each region having a different intensity range, and then render each region with a different density of display elements to represent different brightness level. The procedure of rendering a 3D volume with gray scale distribution is similar.

Data rendering method for volumetric 3D displays

This invention describes methods and systems for correcting frame position error on one category of volumetric 3D displays that generates volumetric 3D images by using a rotary mechanism to move a screen to sweep a volume and projecting 2D profile images on the screen. The screen motion is in general rotating or reciprocating and a mechanism of rotational nature is generally applied to drive the motion. The method has three major steps. The first step provides a measure of the frame position error with respect to the theoretical position. The error is a periodical function of the angular position of the moving screen, due to the nature of the mechanisms. The second step constructs a correction function that shifts the position of frame image of each frame with respect to the frame center to compensate the error. The error measurement and the construction of the correction function can be performed statically or dynamically. The third step shifts the image frames to be displayed according to the correction function and projects them in the volumetric 3D display. This invention also includes preferred driving mechanisms that match the periodical nature of the error function.

Error correction schemes for volumetric 3D displays

This invention relates generally to image projection methods and apparatus for creating color or gray scale images using spatial light modulators (SLMs) without color or gray capability. The basic concept is to divide the pixels on a single SLM into multiple groups and then illuminate each group with a different primary color. The content of the single SLM panel can then be programmed as if there are multiple sub-panels illuminated with different primary colors. The combined image on the single panel therefore displays images of many colors. Illumination can be achieved by projection of a pattern of color or gray scale distribution to the surface of the SLM panel and registering the pattern to corresponding pixel groups; or can be implemented by applying a proximity pattern close to the SLM surface. This technique can be applied to volumetric 3D displays, 2D displays, and optical correlators.

Pattern projection techniques for volumetric 3D displays and 2D displays

This invention relates generally to new and improved methods and apparatus for displaying volumetric 3D images with colors and for barrier-free interaction with the 3D images. A raw 3D dataset is first processed into a viewable data with a geometry description in the form of a collection of scattered points, curves and surfaces, and a corresponding color description. One of the four color combination methods, exact, spatial, temporal, or spatio-temporal, is the used to process the viewable data into three data subsets, each of a collection of points and of a different color frequency. A set of separate image patterns, each pattern of a different color frequency, is then displayed on a color display system according to the content of the three data subsets. In the final step, the set of separate image patterns is recombined and displayed on a volumetric display device to form color volumetric 3D images.

Method and apparatus for displaying volumetric 3D images

This invention relates generally to improved approaches for displaying volumetric three-dimensional (3D) images. The basic idea features improved optical-mechanical mechanisms enabling creation of volumetric 3D images by successive projection of whole frames of 2D images, through an optical-mechanical image delivery system, onto a display plane that moves periodically and sweeps a space. In the rotating approach, two image delivery mechanisms can be used: a revolving multi-mirror system and a revolving orthogonal switchable reflector system. In the reciprocating approach, the image delivery mechanisms include a reciprocating reflector system and a zooming optics.

Moving screen projection technique for volumetric three-dimensional display

This invention relates generally to new and improved approaches for displaying volumnetric three-dimensional (3D) images. The basic idea features new optical-mechanical mechanisms enabling creation of volumetric 3D images by successive projection of whole frames of 2D images. This new method projects a series of frames of 2D images, through an optical-mechanical image delivery system, onto a translucent screen which moves periodically and sweeps a space. As viewed from outside the space, the series of 2D images distributed in the space form a volumetric image because of the after-image effect of human eyes. Many viewers can walk around the space and see the image from omni-directions simultaneously without wearing any kind of glasses.

Moving screen projection technique for volumetric three-dimensional

This invention relates generally to three dimensional volumetric display. Optical data is supplied by an optical data generator through an optical interfacing unit to a rotating display which produces three dimensional volumetric images. The optical interfacing unit transforms non-rotating incoming optical data into rotating optical data which is synchronous with the rotating display. If the optical data generator is viewed backwards along the optical path from the display, looking into the output of the interfacing unit, the position and orientation of the optical data generator will be seen as invariant with respect to the rotating display surface.

Method and apparatus for displaying three-dimensional volumetric images

The invention is a method for making a metal containing article, comprising the steps of: providing a layer of a porous ground in a selected area; exposing selected regions of the layer of porous ground to light, thereby metallizing the selected regions; repeating the foregoing steps a selected number of times to produce a selected number of layers; and selectively modifying the metallized regions of the layers. The initial metallization can be by electroless or semiconductor photo deposition plating. The subsequent modification of the metallized regions can be by electroless plating, electroplating or sintering. It is also possible, in some instances, to forego the second phase modification, the initial phase having provided the desired parameters. In a third preferred embodiment, the invention is a method using an initial metallization phase effected by exposure of a metal salt, such as a metal halide, to light, thereby inducing activation of the halide. A subsequent metallization step is conducted, as well as subsequent modification according to any of the methods mentioned above. A continuous embodiment of the invention is also disclosed, where a continuously deposited bed of powder particles is exposed to light and metallized. Subsequently, the metallized regions are further modified as above. An apparatus for the practice of the continuous methods is also proposed. ?

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Arlington, MA, United States of America

Che-Chih Tsao