International Business Machines Corporation

Doi, Akio

Akio Doi

Koji Koyamada

Takayuki Ito

Kenji Shimada

Akio Koide

Sakae Uno

Tatsuo Miyazawa

Shadow images, which are formed on a light-receiving surface by occluding light emitted from a light source with at least one occluding surface, are drawn by the generating data representative of brightness discontinuity edges that partition the light-receiving surface into loop areas that are completely occluded by the occluding surface and loop areas that are partially or totally irradiated by the light source. An irradiation state is assigned to each loop area. The loop areas are then divided into meshes according to the irradiation state assigned to the loop area. Pixel data is generated for each element of the mesh and output for display on a display device.

System and method for displaying shadows by dividing surfaces by

To provide high-speed volume rendering without computing the points at which a viewing ray intersects with the boundaries of a volume data area. Visualizing a volume entails: selecting the exterior faces that face toward a viewing point from among a plurality of exterior faces of a volume data area, sorting the ones thus selected according to distance from the viewing point, selecting those exterior faces in the sorting order, and determining pixels on a projection plane corresponding to the exterior faces in question by scan conversion; computing pixel values along each viewing ray passing through each pixel for each corresponding exterior face until a final exterior face is encountered; such a final exterior face can be judged from information on many partial solids restricting the volume data area; when a viewing ray enters the volume data area again, pixel values to be added later on another exterior face are computed and added to the previous pixel values; the completion of processing of all exterior faces facing toward a viewing point is tantamount to the completion of processing all viewing rays.

Data visualizer utilizing exterior selected and depth sorted polyhedron

A method and system for displaying a three-dimensional object without requiring depth sorting of polygons or z-buffer calculation. The three-dimensional space is divided into rectangular parallelepipeds and tetrahedrons. A determination of the depth order of the rectangular parallelepipeds and tetrahedrons is made based on a view vector. The rectangles and tetrahedrons are then processed in order of depth from the furthest from the view point to the nearest. As each tetrahedron is processed, geometric data of a polygon containing the iso-valued surface is determined, the intensity of illumination calculated and the polygon data transferred to the display apparatus for display. The method and system of the present invention avoid the need for large memories to store intermediate data.

Method and system for displaying a three dimensional object

Portions showing greater specular reflection of an object to be displayed are displayed with pixels whose opacity, .alpha..sub.1, is emphasized according to the specular reflected component of a shading model, in which case the specular reflected component thus calculated for shading is also utilized for arithmetic operation of emphasized opacity, .alpha..sub.1, and high-speed processing is sought through tabulating various variables such as .alpha..sub.s (an additional opacity introduced for emphasis by a specular reflected component), .alpha..sub.n (a primary opacity), and G (a gradient vector).

Volume rendering method which increases apparent opacity of

This invention relates to a method for generating images by using a ray-tracing method. The method for generating images according to the invention registers only a cell containing the surface of an object among cells that are obtained by dividing the region containing the object to be displayed. The calculation of intersection points is performed only for rectangular parallelepipeds in which the surface exists. Thus it is possible to reduce the time required for displaying the object.

Growing community of inventors

Machida, Japan

Akio Doi