Angel G. Jordan

Bio: Angel G. Jordan is an academic researcher from Carnegie Mellon University. The author has contributed to research in topics: Image compression & Data compression. The author has an hindex of 9, co-authored 15 publications receiving 320 citations.

Image understanding algorithms for remote visual inspection of aircraft surfaces

Abstract: Visual inspection is, by far, the most widely used method in aircraft surface inspection. We are currently developing a prototype remote visual inspection system, designed to facilitate testing the hypothesized feasibility and advantages of remote visual inspection of aircraft surfaces. In this paper, we describe several experiments with image understanding algorithms that were developed to aid remote visual inspection, in enhancing and recognizing surface cracks and corrosion from the live imagery of an aircraft surface. Also described in this paper are the supporting mobile robot platform that delivers the live imagery, and the inspection console through which the inspector accesses the imagery for remote inspection. We discuss preliminary results of the image understanding algorithms and speculate on their future use in aircraft surface inspection.

Intermediate view synthesis considering occluded and ambiguously referenced image regions

Abstract: In this paper, we present an algorithm for synthesizing intermediate views from a single stereo-pair. The key contributions of this algorithm are the incorporation of scene assumptions and a disparity estimation confidence measure that lead to the accurate synthesis of occluded and ambiguously referenced regions. The synthesized views have been displayed on a multi-view binocular imaging system, with subjectively effective motion parallax and diminished eye strain.

Compression of stereo image pairs and streams

Abstract: We exploit the correlations between 3D-stereoscopic left-right image pairs to achieve high compression factors for imageframe storage and image stream transmission. In particular, in image stream transmission, we can find extremely highcorrelations between left-right frames offset in time such that perspective-induced disparity between viewpoints and motion-induced parallax from a single viewpoint are nearly identical; we coin the term "WoridLine correlation' for this condition.We test these ideas in two implementations, (1) straightforward computing of blockwise cross- correlations, and (2)multiresolution hierarchical matching using a wavelet- based compression method. We find that good 3D-stereoscopic imagery can be had for only a few percent more storage space or transmission bandwidth than is required for the corresponding flat imagery.1. INTRODUCTIONThe successful development of compression schemes for motion video that exploit the high correlation between temporallyadjacent frames, e.g., MPEG, suggests that we might analogously exploit the high correlation between spatially or angularlyadjacent still frames, i.e., left-right 3D-stereoscopic image pairs. If left-right pairs are selected from 3D-stereoscopic motionstreams at different times, such that perspective-induced disparity left-right and motion-induced disparity earlier-laterproduce about the same visual effect, then extremely high correlation will exist between the members of these pairs. Thiseffect, for which we coin the term "WorldLine correlation", can be exploited to achieve extremely high compression factorsfor stereo video streams.Our experiments demonstrate that a reasonable synthesis of one image of a left-right stereo image pair can be estimated fromthe other uncompressed or conventionally compressed image augmented by a small set of numbers that describe the localcross-correlations in terms of a disparity map. When the set is as small (in bits) as 1 to 2% of the conventionally compressedimage the stereoscopically viewed pair consisting of one original and one synthesized image produces convincing stereoimagery. Occlusions, for which this approach of course fails, can be handled efficiently by encoding and transmitting errormaps (residuals) of regions where a local statistical operator indicates that an occlusion is probable.Two cross-correlation mapping schemes independently developed by two of us (P.G. and S.S.) have been coded and tested,

A multiresolution framework for stereoscopic image sequence compression

Abstract: Stereoscopic sequence compression typically involves the exploitation of the spatial redundancy between the left and right streams to achieve higher compressions than are possible with the independent compression of the two streams. In this paper the psychophysical property of the human visual system, that only one high resolution image in a stereo image pair is sufficient for satisfactory depth perception, has been used to further reduce the bit rates. Thus, one of the streams is independently coded along the lines of the MPEG standards, while the other stream is estimated at a lower resolution from this stream. A multiresolution framework has been adopted to facilitate such an estimation of motion and disparity vectors at different resolutions. Experimental results on typical sequences indicate that the additional stream can be compressed to about one-fifth of a highly compressed independently coded stream, without any significant loss in depth perception or perceived image quality. >

Compression and interpolation of 3D stereoscopic and multiview video

Abstract: Compression and interpolation each require, given part of an image, or part of a collection or stream of images, being able to predict other parts. Compression is achieved by transmitting part of the imagery along with instructions for predicting the rest of it; of course, the instructions are usually much shorter than the unsent data. Interpolation is just a matter of predicting part of the way between two extreme images; however, whereas in compression the original image is known at the encoder, and thus the residual can be calculated, compressed, and transmitted, in interpolation the actual intermediate image is not known, so it is not possible to improve the final image quality by adding back the residual image. Practical 3D-video compression methods typically use a system with four modules: (1) coding one of the streams (the main stream) using a conventional method (e.g., MPEG), (2) calculating the disparity map(s) between corresponding points in the main stream and the auxiliary stream(s), (3) coding the disparity maps, and (4) coding the residuals. It is natural and usually advantageous to integrate motion compensation with the disparity calculation and coding. The efficient coding and transmission of the residuals is usually the only practical way to handle occlusions, and the ultimate performance of beginning-to-end systems is usually dominated by the cost of this coding. In this paper we summarize the background principles, explain the innovative features of our implementation steps, and provide quantitative measures of component and system performance.

Free-form surface inspection techniques state of the art review

Abstract: Precision inspection has been widely used in manufacturing to measure the dimensional accuracy of parts and products to meet the quality requirements. For regular geometric features, coordinate-measuring machines (CMM) can be used effectively to assess the accuracy and tolerances. For parts with free-form surfaces, the inspection becomes complex. Therefore, numerous researches have been carried out to tackle both fundamental and application issues concerning free-form surface inspection. In addition to academic research, some commercial packages have also been developed. This paper provides a comprehensive literature review of methodologies, techniques and various processes of inspections of parts with free-form surfaces. The specific topics cover: measurement data acquiring methods including contact and non-contact measurement approaches; inspection planning; geometric description methods of design models or measurement data; and, the free-form surface localization and comparison techniques, which are emphasized in this paper and mainly include the establishment of corresponding relationship, 3D transformation solving, measurement data to design model comparison or surface to surface distance calculations. Other issues, such as the influence factors to the localization/registration process, definition and inspection of free-form surface tolerance, and discussions on the functions of some commercial inspection packages available on market, are also discussed.

A survey of perceptual evaluations and requirements of three-dimensional TV

Abstract: A high-quality three-dimensional (3-D) broadcast service (3-D TV) is becoming increasingly feasible based on various recent technological developments combined with an enhanced understanding of 3-D perception and human factors issues surrounding 3-D TV. In this paper, 3-D technology and perceptually relevant issues, in particular 3-D image quality and visual comfort, in relation to 3-D TV systems are reviewed. The focus is on near-term displays for broadcast-style single- and multiple-viewer systems. We discuss how an image quality model for conventional two-dimensional images needs to be modified to be suitable for image quality research for 3-D TV. In this respect, studies are reviewed that have focused on the relationship between subjective attributes of 3-D image quality and physical system parameters that induce them (e.g., parameter choices in image acquisition, compression, and display). In particular, artifacts that may arise in 3-D TV systems are addressed, such as keystone distortion, depth-plane curvature, puppet theater effect, cross talk, cardboard effect, shear distortion, picket-fence effect, and image flipping. In conclusion, we summarize the perceptual requirements for 3-D TV that can be extracted from the literature and address issues that require further investigation in order for 3-D TV to be a success.

View Synthesis for Advanced 3D Video Systems

Abstract: Interest in 3D video applications and systems is growing rapidly and technology is maturating. It is expected that multiview autostereoscopic displays will play an important role in home user environments, since they support multiuser 3D sensation and motion parallax impression. The tremendous data rate cannot be handled efficiently by representation and coding formats such as MVC or MPEG-C Part 3. Multiview video plus depth (MVD) is a new format that efficiently supports such advanced 3DV systems, but this requires high-quality intermediate view synthesis. For this, a new approach is presented that separates unreliable image regions along depth discontinuities from reliable image regions, which are treated separately and fused to the final interpolated view. In contrast to previous layered approaches, our algorithm uses two boundary layers and one reliable layer, performs image-based 3D warping only, and was generically implemented, that is, does not necessarily rely on 3D graphics support. Furthermore, different hole-filling and filtering methods are added to provide high-quality intermediate views. As a result, high-quality intermediate views for an existing 9-view auto-stereoscopic display as well as other stereo- and multiscopic displays are presented, which prove the suitability of our approach for advanced 3DV systems.

Multi-channel television system with viewer-selectable video and audio

Abstract: A television viewer can select among a choice of available camera angles and audio feeds when viewing a sporting event such as a football game without changing the television channel. Audio, video and control data is transmitted in a packetized data stream with control data providing a pre-assigned channel designation (e.g., channel 10 for network X). A set-top terminal receives and processes the data stream according to user-provided commands. The terminal includes software which can be downloaded via the data stream or installed locally. The control data in the data stream is used to provide an on-screen graphical display on the television that allows the user to select the audio and video which correspond to certain areas of the football stadium, for example. Optionally, the viewer may select alternative story lines in a movie or similar program. A default setting provides primary audio and video signals. Alternative audio and video signals are selected by the user and mapped to the channel designator of the primary signal so that the different camera angles and audio feeds may be seen and heard. The viewer is therefore given the opportunity to customize the programming to enhance the entertainment or educational value.

Autonomous inspection and maintenance

Abstract: The different advantageous embodiments may provide an apparatus that may comprise a number of mobile robotic machines, a wireless communications system and a computer system. The number of mobile robotic machines may be capable of moving to a number of locations in a maintenance area and may be capable of performing a number of maintenance operations on a structure in the maintenance area. The wireless communications system may be capable of providing communication with the number of mobile robotic machines within the maintenance area. The computer system may be capable of exchanging information with the number of mobile robotic machines using the wireless communications system.