Abstract: A virtual environment browser (64) holds a number of clip-in files (70, 72, 74) defining guide characters—locally generated visual aids to navigation that appear within a generated image of a virtual environment and follow a user's input (80) navigational commands to provide an advance cue as to the effects of an input command. Where the virtual environment data is supplied from a remote source (62) and includes (78) an indication of a preferred mode for navigating that environment, for example, flying or walking, the browser (64) detects this indication and automatically selects the appropriate guide character. Scaling (84) of the guide character to match the scale of the virtual environment, or such as to render the guide character unobtrusive, may also be provided.

Abstract: A virtual environment browser (64) holds a number of clip-in files (70, 72, 74) defining guide characters—locally generated visual aids to navigation that appear within a generated image of a virtual environment and follow a user's input (80) navigational commands to provide an advance cue as to the effects of an input command. Where the virtual environment data is supplied from a remote source (62) and includes (78) an indication of a preferred mode for navigating that environment, for example, flying or walking, the browser (64) detects this indication and automatically selects the appropriate guide character. Scaling (84) of the guide character to match the scale of the virtual environment, or such as to render the guide character unobtrusive, may also be provided.

Abstract: A method of time-scale modification processing of frame-based digital audio signals based on Synchronous Overlap Addition in which an original frame of digital audio is copied, the original and copied frames are partly overlapped to give a desired new duration to within a predetermined tolerance, the extent of overlap is adjusted within the predetermined tolerance by reference to a cross correlation determination of the best match between the overlapping portions of the original and copied frame; and a new audio frame is generated from the non-overlapping portions of the original and copied frame and by cross-fading between the overlapping portions. To reduce the computational load, a profiling procedure is applied to the original and copied frame prior to cross correlation, such as to reduce the specification of each audio frame portion (100) to a finite array of values (101–106), and the cross correlation is then performed in relation only to the pair of finite arrays of values.

Abstract: An image encoder or other image processing apparatus includes a segmentation apparatus for assigning image pixels to regions, in accordance with predetermined criteria. The segmentation apparatus provides a temporally consistent segmentation throughout a motion picture sequence, and comprises: a motion compensation processor for predicting the segmentation for a current frame (F0) upon the basis of the segmentation (S1) of the preceding frame and estimated motion vectors (M); a pixel identifier and reallocator for modifying the predicted segmentation in dependence upon the accuracy of pixel values (F0′) predicted for the current frame on the basis of the motion vectors (M). In particular, for portions of the image where pixel values are not accurately predicted by the motion vectors, it is assumed that the predicted segmentation is invalid, and such portions are re-segmented and merged into the predicted segmentation to obtain the temporally consistent segmentation.

Abstract: In an optical or magnetic disc audio system, during conventional play the audio is decoded and played from the disc (RDISC) under the direction of a presentation control (PC) and the subcodes indicating time on the disc, track number and so forth are generated. Depending on the system hardware, for some speeds and directions (other than normal play) it may not be possible to decode real subcodes from the disc, and an emulator module (EMU) is switched in at these times. The emulator (EMU) plays a virtual disc (VDISC) using a timer (TIM) and the table of contents (TOC) from the real disc. While the audio is not replayed, the track and time listing display (DISP) is kept up to date, with a typical update for each second of real disc play time. As an extension to this feature, the emulator module (EMU) periodically generates seek commands for the read head in relation to the real disc (RDISC) such that, when normal playback is resumed, there is minimal delay in locating the chosen audio.

Abstract: A data processing apparatus configured as a browser (70) is described for use with a distributed database management utility (72) which handles the accessing of data defining virtual environments via the Internet/World Wide Web (74). Both browser (70) and management utility (72) maintain copies of data files obtained via the Web and passed to the browser, with a memory management stage (80) detecting when apparatus memory reaches a predetermined level of fullness. Based on a stored and system-updated table (84) identifying the passing of data files from management utility to browser, the memory manager (80) identifies which of the management utility held copies of the files to delete in order to create memory space.

Abstract: A data processing apparatus configured as a browser (70) is described for use with a distributed database management utility (72) which handles the accessing of data defining virtual environments via the Internet/World Wide Web (74). Both browser (70) and management utility (72) maintain copies of data files obtained via the Web and passed to the browser, with a memory management stage (80) detecting when apparatus memory reaches a predetermined level of fullness. Based on a stored and system-updated table (84) identifying the passing of data files from management utility to browser, the memory manager (80) identifies which of the management utility held copies of the files to delete in order to create memory space.

Abstract: A virtual body modelling apparatus and method models a users body in a virtual environment and animated to follow physical movements of the user. Stores (30,32) hold data defining the virtual environment as well as features of the virtual body representation, including sequences of virtual body motions (for example a walking sequence for the legs of the virtual body) which sequences are initiated in response to one or more predetermined physical movements by the user, and animated by a display generator (28) providing images of the virtual environment to the user. Various forms of feedback to the user are provided, including force feedback where the users physical movements are constrained in dependence on conditions within the virtual environment, visual feedback where the users viewpoint of the virtual world is modified as a sequence of body motions is executed, and audio feedback (62) such as the sound of footsteps triggered at predetermined points in the sequence of motions.

Abstract: An image encoder or other image processing apparatus includes a segmentation apparatus for assigning image pixels to regions, in accordance with predetermined criteria. The segmentation apparatus provides a temporally consistent segmentation throughout a motion picture sequence, and comprises: a motion compensation processor for predicting the segmentation for a current frame (F0) upon the basis of the segmentation (S1) of the preceding frame and estimated motion vectors (M); and a pixel identifier and reallocator for modifying the predicted segmentation in dependence upon the accuracy of pixel values (F0′) predicted for the current frame on the basis of the motion vectors (M). In particular, for portions of the image where pixel values are not accurately predicted by the motion vectors, it is assumed that the predicted segmentation is invalid, and such portions are re-segmented and merged into the predicted segmentation to obtain the temporally consistent segmentation.

Abstract: A data browser is described for accessing data defining virtual environments via the Internet/World Wide Web. In conjunction with at least one store (44) of virtual environment assets, such as audio, video, graphics textures and so forth, a list (62) is maintained recording the identity of the stored assets received via the Web, suitably in the form of their respective URL's. Browser applications requiring assets from the store (44) scan the master list to determine whether a particular asset is already stored there on encountering a program requirement for that asset to avoid the need to access the remote source of asset data via the Web. Where the assets are distributed over more than one storage device (44, 60), each device is suitably provided with such a contents list.

Abstract: A method and apparatus are provided for providing user-directed operation of a virtual manipulator, such as a simulated hand or claw (30) within a computer-generated virtual environment. The environment comprises one or more objects (32) which may be held, released or impelled by the manipulator under user control. Movement of the virtual manipulator is directed by a suitable hand held device operated by a user, with a simple control directing opening or closing of the claw (30). In operation, actions such as throwing, catching or punching an object (32) are partially automated, with the decision as to the action initiated being determined by the separation (D) between object and manipulator, and the current and previous states of each as recorded in the form of respective state variables. A method for the derivation of an applied velocity for the object acted upon is also described.

Abstract: A method and apparatus are described for controlling a computer-generated animation suite (32), where the suite generates sequences of image frames from stored libraries of image components and component motion parameters. An interface (42) includes a store (44) of function specifications each of which, when called and applied to the animation suite, initiates one or a predetermined sequence of image component movements. A rule-based processor (10) comprises means for modelling an asynchronous logic circuit as a plurality of circuit elements the functions of which are governed by a stored set (14,22) of rules each defining a response to a given condition with the processor generating a response when the associated condition is satisfied. Predetermined conjunctions of image frame features are specified as the condition portion of some of the rules, and the calling of each of the interface function specifications is the response portion of a respective rule.

Abstract: A method and apparatus are described for post-processing a computer-generated image of a three-dimensional object for display as a pixel image. A focus depth is specified either by a user or from within the system for each image frame. The image pixels are grouped into non-overlapping blocks of adjoining image pixels with a single respective depth value pre-specified or calculated at run-time for each block. Each block is extracted in turn from the image and the pixels within a block are convolution filtered with a common set of filter coefficients. Padding may be applied to fill areas where a full filter kernel cannot be formed. The technique has particular suitability for MPEG-coded image streams where the existing MPEG macroblock specification may be taken advantage of.

Abstract: An interactive entertainment apparatus is provided having means (10,14) for modelling a virtual environment populated by modelled characters, with each of the characters being controlled by respective rule-based agents. A camera control function (58) within the apparatus processor periodically monitors at least one compiled behavior per character agent, together with the respective locations within the virtual environment for each of the characters. The processor (10) generates clusters of adjacent characters within the virtual environment in accordance with predetermined clustering criteria such as relatively proximity and commonality of behavioral characteristics, and generates a respective cluster value derived from the current settings of the monitored behaviors within that cluster.

Abstract: In an image source for multimedia applications such as networked computer games, a graphics engine (16) generates pixel images one line at a time using a scan-line algorithm and supplies the generated scan lines to an encoder (18) where they are buffered. The encoder codes the buffered pixel data as macroblocks of, for example 16.times.16 pixels according to MPEG or similar standards. When the graphics engine has sent sufficient scan lines for a first macroblock to the encoder, it sends a signal (FLAG) on receipt of which the encoder begins coding the pixel data as a macroblock in a line of macroblocks whilst continuing to receive scan lines from the graphics engine (16). To increase encoder efficiency, the graphics engine specifies to the encoder global (GMV) and macroblock (BMV) motion vectors for substantially all or selected ones of the macroblocks of an image respectively.

Abstract: A post-processing method and apparatus to produce focus/defocus effects in computer generated images of three dimensional objects. A convolution filter stores pixel values (V) and associated depth values (Z) with a filter kernel being selected from a look-up table in dependence of the depth of the centre pixel (Z.sub.c) in relation to a specified focus depth (P). To minimize spurious effects where filter kernels overlap objects at different depths in the image, an inhibition function stage varies the amount by which each pixel contributes to the kernel in dependence on that pixel's depth value (Z) and the centre pixel and focus depth values (Z.sub.c and P). Inhibition profiles over a range of contributing and centre pixel values are provided.

Abstract: An apparatus is provided for modelling and interacting with a virtual environment. An image of the environment, and a representation of the user's presence therein, is generated by a CPU (12) based on data from memories (14,16) and supplied to the user by a stereoscopic display (10). The user is provided with a hand-held unit (18) which has a single control button (20). When the button (20) is not pressed, the user's movements of the control (18) are replicated by a modelled icon (such as a virtual hand) within the virtual environment to enable interaction. When the button (20) is actuated, the user's movements of control device (18) are instead converted to navigational commands shifting the location of the user's virtual presence around the virtual environment.

Abstract: A feedback means is provided in conjunction with a cursor control mechanism for a two- or three-dimensional graphic user interface. Feedback levels are determined by tonal variation (grey scale or color component) at the pixel (P) currently indicated by the cursor. Suitably, the levels are set by generating differentials across a patch of pixels (A) surrounding the indicated pixel, with differential generation in mutually perpendicular directions (X and Y) providing for independent feedback in two or three directions. The technique enables interface features such as window boundaries (36) or textured patches to be identified to the user without specially authored software being required for those features to trigger feedback when indicated.

Abstract: A collision warning system is for a head mounted display (HMD) (10) worn by a user, for example as the interface to a virtual reality system, to warn of nearby objects in the physical environment. A motion detector (30,32) detects positional changes of the HMD, which changes are reflected in changes of a displayed image viewpoint, and a comparator stage (38,40) determines whether the movement takes the user into a "prohibited" area. If so, a visual and/or audible warning is provided to the user via the HMD (10). In an embodiment, the display screens (18) of the HMD include liquid crystal display shutters (20) which are switched to a transparent state in the event of an imminent collision such that the user is not only warned of the danger but also able to see it without having to remove or adjust the HMD.

Abstract: A face classification system which receives video data representative of a scene and extracts therefrom data representative of a face which is present in the scene. The facial video data is applied to a homomorphic filter to eliminate the effects of lighting changes in the scene. The positions of the eyes and mouth are located to form two sub-divisions, one in relation to a first line joining the eyes and the other in relation to a second line perpendicular to the first line and passing through the nose. A feature vector which is representative of the face and is rotation, scaling, translation and grey level intensity invariant is then produced by applying a recursive second order sub-division of moments to the filtered data. Such sub-division of moments is constrained to act first on the sub-divisions formed by the aforesaid lines, thereby reducing the effect of noise.