Perspective Images Research Articles

Monocular multi-view stereo imaging system

In this study, we present a single-camera, multi-view stereo imaging system for capturing three-dimensional (3D) information. First, we design a monocular, multi-view stereo imaging device composed of a fisheye lens, and planar mirrors placed around the lens. The fisheye lens has a wide view-angle. The captured image includes a centered region of direct observation and surrounding regions of mirrored observations. These regions can be considered as images captured by multiple cameras at different positions and orientations. Therefore, the proposed device is equivalent to a synchronous multiple-cameras configuration, in which all the cameras share the same physical characteristics. In addition, we show how to place the mirrors in order to maximize the common view-angles, which is an important design consideration. Then, after calibrating the projection function of the fisheye lens, we obtain the positions and orientations of the virtual cameras from the external parameters. We also develop two multi-baseline stereo algorithms for the 3D measurement system. The first algorithm transforms the captured image to perspective images, and uses the traditional method to perform stereo determination. The second algorithm directly uses the original captured image along with an analysis of the epipolar geometry. Experimental results show that our system is more effective than traditional stereo methods that use a stereo pair, and it can achieve robust 3D reconstruction.

Components of Global Quality of Life In Multiple Myeloma

AbstractAbstract 4735 Introduction:Symptoms of multiple myeloma (MM) and the adverse events (AEs) associated with MM treatment can be debilitating on many levels. A better understanding of the extent to which patients are affected and how this in turn impacts global health-related quality of life (HRQOL) can improve management of patients. Methods:A survey in 11 centers in the United Kingdom and Germany gathered, among other items, data on HRQOL, measured by the European Organization for Research and Treatment of Cancer's (EORTC) generic cancer and MM modules (QLQ-C30 and QLQ-MY20 scales), from a cross-section of patients with multiple myeloma at various phases of the disease. The QLQ-C30 is comprised of a global QOL domain, 5 functional and 3 symptom domains, and 6 AE items; the QLQ-MY20 includes scales for disease symptoms, treatment side-effects, future perspective and body image. This analysis aimed to explore the association between individual QOL scales (from QLQ-C30 and QLQ-MY20) and global QOL. Values for each scale range from 0 to 100; higher values indicate better HRQOL for the global, functional, future perspective and body image scales, and worse HRQOL for the AE items, symptom domains, disease symptoms and side-effects scales. Scoring of the QLQ-C30 and MY-20 scales was described previously by Fayers et al. [i] and Cocks et al. [ii] respectively. The distribution and correlations (Spearman) between the various scales was explored. Moreover, a multiple linear regression analysis was carried out to assess the association between individual scales and global QOL (from QLQ-C30) with the aim to identify those that independently impact global QOL. Each scale was first considered alone as a predictor of global QOL; those with a statistically significant association at a p-value ≤ 0.10 were included in a multiple regression model. This was then trimmed to exclude scales that became non-significant (p-value > 0.10). Results:The survey included 154 patients: 63.0% were male and the mean age was 66.4 (SD: 10.0). Mean time since diagnosis was 3.7 years (SD: 3.7), 51.9% were currently on treatment, and 42.9% had at least one prior line of MM therapy. The mean global QOL score was 60.1 (SD: 25.5), with the middle two quartiles of patients scoring between 41.7 and 83.3. Cognitive and emotional functioning scores had means near or above 80, suggesting that these aspects of HRQOL were less affected than role (62.9 (IQR: 33.3–100)), social (63.9(IQR: 33.3–100)) and physical functioning (68.7(IQR:53.3-93.3)). While body image scores were generally high (77.9 (IQR:66.7-100)), future perspective appeared to be relatively more affected (59.9 (33.3-77.8)). Patients' HRQOL is most affected by pain and fatigue (based on symptom and AE scales of the QLQ-C30), with means above 30, followed by insomnia and dyspnoea with means above 20, while diarrhea and nausea/vomiting scales had the lowest mean scores (below 10). The Disease Symptom (23.3 (IQR:0-38.9)) and Side Effect scale scores (19.5 (IQR:7.4-29.6)) from the QLQ-MY20 were consistent with the AE and symptom scales from the QLQ-C30. All of the domains except diarrhea and nausea/vomiting individually showed at least moderate correlations with global QOL (Spearman correlations above 0.25 in absolute value), but also exhibited strong correlations between themselves. The final multiple regression model retained physical and social functioning, fatigue, disease symptoms (QLQ-MY20) and future perspective scales (QLQ-MY20), all of which had relatively similar strength of association with global QOL. Conclusion:This study demonstrates that the impact of MM and treatment AEs can be seen on various dimensions of patients' HRQOL, particularly reduced physical and social functioning, future perspective and various disease symptoms such as bone pain (as captured by the disease symptoms scale of the QLQ-MY20) and fatigue. Fayers P, Aaronson N, Bjordal K, Groenvold M, Curran D, Bottomley A: The EORTC QLQ-C30 Scoring Manual. 3 Edition EORTC Quality of Life Group, Brussels 2001. [ii]Cocks K, Cohen D, Wisloff F, et al. An international field study of the reliability and validity of a disease-specific questionnaire module (the QLQ-MY20) in assessing the quality of life of patients with multiple myeloma. Eur J Cancer 2007;43:1670-1678. Disclosures:Williams:Celgene: Honoraria; Jansen Cilag: Consultancy, Honoraria. Off Label Use: Some of the patients in the study received Thalidomide for the treatment of relapsed or refractory multiple myeloma. Proskorovsky:United BioSource Corporation: Consultancy, Research Funding. Lewis:Celgene International SARL: Employment. Ishak:United BioSource Corporation: Consultancy, Research Funding. Payne:United BioSource Corporation: Consultancy, Research Funding. Lordan:United BioSource Corporation: Consultancy, Research Funding. Davies:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria, Speakers Bureau. Peters:Celgene: Consultancy.

Robust and accurate fundamental matrix estimation with propagated matches

Two perspective images of a single scene taken by uncalibrated cameras are related by a fundamental matrix, which is the key to solving many computer vision problems. We present a new robust and accurate algorithm to estimate the fundamental matrix, which is suitable for wide baseline stereo pairs. The estimation algorithm includes two stages. The first stage is that more affine invariant matching points are determined by a propagation process. In this stage, an affine iterative optimization model is used to accurately detect matching points at the subpixel level. And a new matching cost function is proposed that is more robust to outliers and more effective for images with single texture and repetitive texture. In the second stage, a resampling model based on the posterior probability is presented in order to optimize the fundamental matrix with more accurate matching points. The experiment results show that our algorithm is very robust to outliers, and the fundamental matrix with high accuracy can be estimated.

Optical simulation for cross‐talk evaluation and improvement of autostereoscopic 3‐D displays with a projector array

Abstract— Multi‐view spatial‐multiplexed autostereoscopic 3‐D displays normally use a 2‐D image source and divide the pixels to generate perspective images. Due to the reduction in the resolution of each perspective image for a large view number, a super‐high‐resolution 2‐D image source is required to achieve 3‐D image quality close to the standard of natural vision. This paper proposes an approach by tiling multiple projection images with a low magnification ratio from a microdisplay to resolve the resolution issue. Placing a lenticular array in front of the tiled projection image can lead to an autostereoscopic display. Image distortion and cross‐talk issues resulting from the projection lens and pixel structure of the microdisplay have been addressed with proper selection of the active pixel and adequate pixel grouping and masking. Optical simulation has shown that a 37‐in. 12‐view autostereoscopic display with a full‐HD (1920 × 1080) resolution can be achieved with the proposed 3‐D architecture.

PANORAMIC 3D RECONSTRUCTION USING STEREO MULTI-PERSPECTIVE PANORAMA

In this paper, we present a novel approach to imaging a panoramic (360°) environment and computing its dense depth map. Our approach adopts a multi-baseline stereo strategy using a set of multi-perspective panoramas where large baseline lengths are available. We design two image acquisition rigs for capturing such multi-perspective panoramas. The first one is composed of two parallel stereo cameras. By rotating the rig about a vertical axis, we generate four multi-perspective panoramas by resampling the regular perspective images captured by the stereo cameras. Then a depth map is estimated from the four multi-perspective panoramas and an original perspective image using a multi-baseline matching technique with different types of epipolar constraints. The second one is composed of a single camera and two mirrors. By rotating the rig, we acquire a spatio-temporal volume that is made up of the sequential images captured by the camera. Then we estimate a depth map by extracting trajectories from the spatio-temporal volume by using a multi-baseline stereo technique by considering occlusions. We can consider both rotating rigs as a single rotating camera with a very large field of view (FOV), that offers a large baseline length in depth estimation. In addition, compared with a previous approach using two multi-perspective panoramas from a single rotating camera, our approach can reduce matching errors due to image noise, repeated patterns, and occlusions by multi-baseline stereo techniques. Experimental results using both synthetic and real images show that our approach produces high quality panoramic 3D reconstruction.

Stereoscopic display with reproduction of perspective images in intersecting planes

A stereoscopic display has been created that reproduces the left and right sides of a stereo pair in intersecting observation planes. The display thus constructed makes it possible to eliminate splitting of the stereoscopic image when a stereo pair is reproduced from cameras with convergent optical axes.

Image warps for artistic perspective manipulation

Painters and illustrators commonly sketch vanishing points and lines to guide the construction of perspective images. We present a tool that gives users the ability to manipulate perspective in photographs using image space controls similar to those used by artists. Our approach computes a 2D warp guided by constraints based on projective geometry. A user annotates an image by marking a number of image space constraints including planar regions of the scene, straight lines, and associated vanishing points. The user can then use the lines, vanishing points, and other point constraints as handles to control the warp. Our system optimizes the warp such that straight lines remain straight, planar regions transform according to a homography, and the entire mapping is as shape-preserving as possible. While the result of this warp is not necessarily an accurate perspective projection of the scene, it is often visually plausible. We demonstrate how this approach can be used to produce a variety of effects, such as changing the perspective composition of a scene, exploring artistic perspectives not realizable with a camera, and matching perspectives of objects from different images so that they appear consistent for compositing.

Image warps for artistic perspective manipulation

Painters and illustrators commonly sketch vanishing points and lines to guide the construction of perspective images. We present a tool that gives users the ability to manipulate perspective in photographs using image space controls similar to those used by artists. Our approach computes a 2D warp guided by constraints based on projective geometry. A user annotates an image by marking a number of image space constraints including planar regions of the scene, straight lines, and associated vanishing points. The user can then use the lines, vanishing points, and other point constraints as handles to control the warp. Our system optimizes the warp such that straight lines remain straight, planar regions transform according to a homography, and the entire mapping is as shape-preserving as possible. While the result of this warp is not necessarily an accurate perspective projection of the scene, it is often visually plausible. We demonstrate how this approach can be used to produce a variety of effects, such as changing the perspective composition of a scene, exploring artistic perspectives not realizable with a camera, and matching perspectives of objects from different images so that they appear consistent for compositing.

A Novel Image Correlation Matching Approach

In this paper we present a novel approach which is com bined local invariant feature descriptor named ARPIH (Angular Radial Partitioning Intensity Histogram) with histogram-based similar distance (HSD). The approach succeeds the ARPIH descriptor’s distinctive advantage and provides higher robustness in deformation image matching, such as rotation image, illumination changing image and perspective image, etc. Based on the MCD algorithm, we present the HSD algorithm . This algorithm transforms the image matching into the histogram matching by calculat ing the number of the similar points between template histogram and target histogram in order to decrease the calculation complicacy and improve the matching efficiency. A large amount groups of images are used in testing the approach presented in this paper. The matching results presented here indicate that the presented algorithm is efficient to figure out both the geometric deformation image matching and the illumination changing image matching. Contrast with the traditional matching algorithm, the approach presented in this paper has the obvious advantage of high matching precision, robustness and performance efficiency.

Omnidirectional Image Stabilization for Visual Object Recognition

In this paper, we present a pipeline for camera pose and trajectory estimation, and image stabilization and rectification for dense as well as wide baseline omnidirectional images. The proposed pipeline transforms a set of images taken by a single hand-held camera to a set of stabilized and rectified images augmented by the computed camera 3D trajectory and a reconstruction of feature points facilitating visual object recognition. The paper generalizes previous works on camera trajectory estimation done on perspective images to omnidirectional images and introduces a new technique for omnidirectional image rectification that is suited for recognizing people and cars in images. The performance of the pipeline is demonstrated on real image sequences acquired in urban as well as natural environments.

Attentional processes and meditation

Visual attentional processing was examined in adult meditators and non-meditators on behavioral measures of change blindness, concentration, perspective-shifting, selective attention, and sustained inattentional blindness. Results showed that meditators (1) noticed more changes in flickering scenes and noticed them more quickly, (2) counted more accurately in a challenging concentration task, (3) identified a greater number of alternative perspectives in multiple perspectives images, and (4) showed less interference from invalid cues in a visual selective attention task, but (5) did not differ on a measure of sustained inattentional blindness. Together, results show that regular meditation is associated with more accurate, efficient, and flexible visual attentional processing across diverse tasks that have high face validity outside of the laboratory. Furthermore, effects were assessed in a context separate from actual meditation practice, suggesting that meditators' better visual attention is not just immediate, but extends to contexts separate from meditation practice.

Perspective in a box

Perspective is an optional subject for students of some levels in Dutch secondary schools. A proper final task on this subject is the analysis of existing perspective drawings or paintings. This task is sometimes supplemented by a more creative and challenging assignment, that is, the design and construction of a perspective box. A perspective box is an empty box with, on the inner sides, perspective pictures giving a surprising spatial effect when observed through the peephole. The students who take up the challenge are in the first place inspired by the six still existing antique wooden perspective boxes, especially because they were created by Dutch seventeenth-century painters of architecture and interiors. In this article the setup of the perspective in these boxes will be discussed. But for a clear comprehension, we begin by reviewing the principles of linear perspective and their implications for the way perspective images can best be viewed.

Multi‐Perspective Modelling, Rendering and Imaging

Abstract A perspective image represents the spatial relationships of objects in a scene as they appear from a single viewpoint. In contrast, a multi‐perspective image combines what is seen from several viewpoints into a single image. Despite their incongruity of view, effective multi‐perspective images are able to preserve spatial coherence and can depict, within a single context, details of a scene that are simultaneously inaccessible from a single view, yet easily interpretable by a viewer. In computer vision, multi‐perspective images have been used for analysing structure revealed via motion and generating panoramic images with a wide field‐of‐view using mirrors. In this STAR, we provide a practical guide on topics in multi‐perspective modelling and rendering methods and multi‐perspective imaging systems. We start with a brief review of multi‐perspective image techniques frequently employed by artists such as the visual paradoxes of Escher, the Cubism of Picasso and Braque and multi‐perspective panoramas in cel animations. We then characterize existing multi‐perspective camera models, with an emphasis on their underlying geometry and image properties. We demonstrate how to use these camera models for creating specific multi‐perspective rendering effects. Furthermore, we show that many of these cameras satisfy the multi‐perspective stereo constraints and we demonstrate several multi‐perspective imaging systems for extracting 3D geometry for computer vision. The participants learn about topics in multi‐perspective modelling and rendering for generating compelling pictures for computer graphics and in multi‐perspective imaging for extracting 3D geometry for computer vision. We hope to provide enough fundamentals to satisfy the technical specialist without intimidating curious digital artists interested in multi‐perspective images. The intended audience includes digital artists, photographers and computer graphics and computer vision researchers using or building multi‐perspective cameras. They will learn about multi‐perspective modelling and rendering, along with many real world multi‐perspective imaging systems.

Cartoon synthesis using constrained spreading activation network

In this paper, we propose an approach to synthesize cartoons from the existing cartoon data by controlling the character's path which is defined by the cartoonists in a background image. First, detailed pre-experiments are conducted in which different cartoon features are extracted and compared. During the pre-experiments, three features extracted from edge, motion and color are demonstrated effectively for evaluating cartoon similarity according to the quantitative analysis. The three features are then fused and a Cartoon Frame Relationship Network is constructed. Based on the graph, we propose a Constrained Spreading Activation Algorithm to select candidate frames which are visually similar to the current frame to generate the next frame. The cartoons are synthesized by choosing the most appropriate frame from the candidates in accordance with the path designed by the cartoonists. When the new cartoons are applied into the background image, our approach coordinates the cartoon character's size according to the image's perspective as well. The experiment results demonstrate that the combination of the three proposed features are effective in similarity evaluation, and the candidates selected by Constrained Spreading Activation Algorithm, are more similar to the current frame compared with other algorithms. The results also show that our approach can synthesize visually smooth cartoons from the existing cartoon library.

On improved calibration method for the catadioptric omnidirectional vision with a single viewpoint

The single viewpoint constraint is a principal optical characteristic for most catadioptric omnidirectional vision. Single viewpoint catadioptric omnidirectional vision is very useful because it allows the generation of geometrically correct perspective images from one omnidirectional image. Therefore precise calibration for single viewpoint constraint is needed during system assembling. However, in most image detection based calibration methods, the nonlinear optical distortion brought by lens is often neglected. Hence the calibration precision is poor. In this paper, a new calibration method of single viewpoint constraint for the catadioptric omni-directional vision is proposed. Firstly, an image correction algorithm is obtained by training a neural network. Then, according to characteristics of the space circular perspective projection, the corrected image of the mirror boundary is used to estimate its position and attitude relative to the camera to guide the calibration. Since the estimate is conducted based on actual imaging model rather than the simplified model, the estimate error is largely reduced, and the calibration accuracy is significantly improved. Experiments are conducted on simulated images and real images to show the accuracy and the effectiveness of the proposed method.

Depth perception for moving images shown on a large LED display with an aperture grille

Abstract— A type of depth illusion created by the use of an aperture grille is reported. When viewing a moving target through multiple slits, a movement with depth is perceived, which was originally reported (see Ref. 11). The binocular delay is considered to cause a virtual disparity between both perspective images with apparent movement. By using an LED display with an aperture grille as a stereoscopic display, perceived distance caused by a binocular delay has been measured. The measured distance is compared with the perceived distance for stereoscopic still images shown on a stereoscopic LED panel. The comparison supported that the binocular delay is converted into binocular disparity. Furthermore, pair‐comparison tests were conducted to investigate depth impressions. It was found that use of an aperture grille improves depth impression for a movie that was taken with a laterally moving camera.

Egg freshness detection based on digital image technology

Yolk index and air room height, two main measures for egg freshness detection, are very difficult to be accurately measured in practices. This paper investigated an image-based egg freshness detection method. The perspective image of egg was obtained by computer vision device. The characteristic regions, including the yolk region and air room region were separated from the obtained egg picture by image processing. The pixel areas and lengths of the above characteristic regions were respectively calculated and analyzed. The relative ratios of the pixel area and length of characteristic regions to that of the whole egg region were selected as characteristic parameters. It was shown that the above relative ratios increased while egg freshness reduced according to a detailed analysis. Three detection models of egg freshness were set up based on the correlations between the characteristic parameters and freshness. The test results showed that the accuracy rates of these models were 93, 94 and 92% respectively. The egg freshness detection based on image characteristic of yolk and air room was efficient and feasible. Key words: Egg yolk, air room, freshness, digital image, computer vision.

Forensic Terrestrial Photogrammetry from a Single Image

Forensic terrestrial photogrammetry is one of the most valuable and low-cost resources of spatial data available today. Due to the ephemeral crime scene characteristics, these photographs can often capture information that is never to be seen again. This paper presents a novelty approach for the documentation, analysis, and visualization of crime scenes for which only a single perspective image is available. The photogrammetric process consists of a few well-known steps in close-range photogrammetry: features extraction, vanishing points computation, camera self-calibration, 3D metric reconstruction, dimensional analysis, and interactive visualization. Likewise, the method incorporates a quality control of the different steps accomplished sequentially. As a result, several cases of study are presented in the experimental results section in order to test their viability. The full approach can be applied easily through the free software, sv3DVision, which has been evaluated by a number of police officers, forensic scientists, and forensic educators satisfactorily.

Creating and delivering augmented scenes

An augmented scene delivery system (ASDS) creates and distributes annotated cartographic products in real time from captured still imagery. An ASDS applies augmented reality technology to the visualization of unrestricted exterior viewsheds through an adaptive, perspective‐based surface resampling model. This paper describes an ASDS testing platform, introduces a client/server model for distributing augmented scenes over the Internet, presents a linear‐time algorithm for resampling dense elevation models for perspective imaging and conducts an execution analysis of the algorithm's implementation, demonstrating that augmented scenes can be constructed and delivered efficiently. The paper also presents a migration path to mobile ASDS platforms with a discussion of the remaining technological problems associated with its implementation.

Three-Dimensional Object Recognition With Multiview Photon-Counting Sensing and Imaging

We present a method for photon-counting sensing with three-dimensional (3-D) integral imaging for object recognition using independent component analysis (ICA). A lenslet array is used to capture multiple perspective images of a 3-D scene projected onto an image sensor. Photon-counting images of the captured elemental images are generated using a Poisson distribution. A kurtosis-maximization-based algorithm is used as a non-Gaussian maximization method to extract independent features from the photon-counting training data set. The photon-counting image data are preprocessed using principal component analysis to reduce the number of dimensions, increase the speed of the ICA step, and improve the classification performance. A photon-counting image of unknown input scene is classified using k-nearest neighbor and cosine angle metrics. Experimental results are presented, and the probability of classification errors is measured.