Stereo matching is one of the most active research areas in computer vision. While a large number of algorithms for stereo correspondence have been developed, relatively little work has been done on characterizing their performance. In this paper, we present a taxonomy of dense, two-frame stereo methods designed to assess the different components and design decisions made in individual stereo algorithms. Using this taxonomy, we compare existing stereo methods and present experiments evaluating the performance of many different variants. In order to establish a common software platform and a collection of data sets for easy evaluation, we have designed a stand-alone, flexible C++ implementation that enables the evaluation of individual components and that can be easily extended to include new algorithms. We have also produced several new multiframe stereo data sets with ground truth, and are making both the code and data sets available on the Web.

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A taxonomy and evaluation of dense two-frame stereo correspondence algorithms

Humans perceive the three-dimensional structure of the world with apparent ease. However, despite all of the recent advances in computer vision research, the dream of having a computer interpret an image at the same level as a two-year old remains elusive. Why is computer vision such a challenging problem and what is the current state of the art? Computer Vision: Algorithms and Applications explores the variety of techniques commonly used to analyze and interpret images. It also describes challenging real-world applications where vision is being successfully used, both for specialized applications such as medical imaging, and for fun, consumer-level tasks such as image editing and stitching, which students can apply to their own personal photos and videos. More than just a source of recipes, this exceptionally authoritative and comprehensive textbook/reference also takes a scientific approach to basic vision problems, formulating physical models of the imaging process before inverting them to produce descriptions of a scene. These problems are also analyzed using statistical models and solved using rigorous engineering techniques Topics and features: structured to support active curricula and project-oriented courses, with tips in the Introduction for using the book in a variety of customized courses; presents exercises at the end of each chapter with a heavy emphasis on testing algorithms and containing numerous suggestions for small mid-term projects; provides additional material and more detailed mathematical topics in the Appendices, which cover linear algebra, numerical techniques, and Bayesian estimation theory; suggests additional reading at the end of each chapter, including the latest research in each sub-field, in addition to a full Bibliography at the end of the book; supplies supplementary course material for students at the associated website, http://szeliski.org/Book/. Suitable for an upper-level undergraduate or graduate-level course in computer science or engineering, this textbook focuses on basic techniques that work under real-world conditions and encourages students to push their creative boundaries. Its design and exposition also make it eminently suitable as a unique reference to the fundamental techniques and current research literature in computer vision.

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Computer Vision: Algorithms and Applications

Nanostructured carbon materials are potentially of great technological interest for the development of electronic1,2, catalytic3,4 and hydrogen-storage systems5,6. Here we describe a general strategy for the synthesis of highly ordered, rigid arrays of nanoporous carbon having uniform but tunable diameters (typically 6 nanometres inside and 9 nanometres outside). These structures are formed by using ordered mesoporous silicas as templates, the removal of which leaves a partially ordered graphitic framework. The resulting material supports a high dispersion of platinum nanoparticles, exceeding that of other common microporous carbon materials (such as carbon black, charcoal and activated carbon fibres). The platinum cluster diameter can be controlled to below 3 nanometres, and the high dispersion of these metal clusters gives rise to promising electrocatalytic activity for oxygen reduction, which could prove to be practically relevant for fuel-cell technologies. These nanomaterials can also be prepared in the form of free-standing films by using ordered silica films as the templates.

Ordered nanoporous arrays of carbon supporting high dispersions of platinum nanoparticles

Cell phones and other portable devices are equipped with a variety of technologies by which existing functionality can be improved, and new functionality can be provided. Some relate to visual search capabilities, and determining appropriate actions responsive to different image inputs. Others relate to processing of image data. Still others concern metadata generation, processing, and representation. Yet others relate to coping with fixed focus limitations of cell phone cameras, e.g., in reading digital watermark data. Still others concern user interface improvements. A great number of other features and arrangements are also detailed.

Methods and Systems for Content Processing

We propose a new approach to the correspondence problem that makes use of non-parametric local transforms as the basis for correlation. Non-parametric local transforms rely on the relative ordering of local intensity values, and not on the intensity values themselves. Correlation using such transforms can tolerate a significant number of outliers. This can result in improved performance near object boundaries when compared with conventional methods such as normalized correlation. We introduce two non-parametric local transforms: the rank transform, which measures local intensity, and the census transform, which summarizes local image structure. We describe some properties of these transforms, and demonstrate their utility on both synthetic and real data.

/pdf/non-parametric-local-transforms-for-computing-visual-22u33vp6qp.pdf

Non-parametric local transforms for computing visual correspondence

The concept of a real-time range camera without moving parts is described, based on the time-of-flight (TOF) principle. It operates with modulated visible and near-infrared radiation, which is detected and demodulated simultaneously by a 2-D array of lock-in pixels employing the charge-coupled device principle. Each pixel individually measures the amplitude, offset and phase of the received radiation. The theoretical resolution limit of this TOF range camera is derived, which depends on the square root of the detected background radiation and the inverse of the modulation amplitude. Actual measurements of 3-D sequences acquired at 10 range images per second show excellent agreement between our theory and the observed results. A range resolution of a few centimeters over a range of 10 m, with an illumination power of a few hundreds of milliwatts is obtained in laboratory scenes for noncooperative, diffusely reflecting objects.

Solid-state time-of-flight range camera

A device and method for spatially resolved photodetection and demodulation of temporally modulated electromagnetic waves makes it possible to measure phase, amplitude and offset of a temporally modulated, spatially coded radiation field. A micro-optical element ( 41 ) spatially averages a portion ( 30 ) of the scene and equally distributes the averaged intensity on two photo sites ( 51.1.51.2 ) close to each other. Adjacent to each of these photo sites ( 51.1 ) are two storage areas ( 54.1, 54.2 ) into which charge from the photo site can be moved quickly (with a speed of several MHz to several tens or even hundreds of MHz) and accumulated essentially free of noise. This is possible by employing the charge-coupled device (CCD) principle. The device combines a high optical fill factor, insensitivity to offset errors, high sensitivity even with little light, simultaneous data acquisition, small pixel size, and maximum efficiency in use of available signal photons for sinusoidal as well as pulsed radiation signals. The device and method may be used in a time-of-flight (TOF) range imaging system without moving parts, offering 2D or 3D range data.

Device and method for spatially resolved photodetection and demodulation of modulated electromagnetic waves

A new type of CCD image sensor for two-dimensional synchronous detection ("lock-in imager") is presented. The measurement principle allows each pixel to measure the size of the amplitude modulation, the relative phase and the mean brightness level (background) of an oscillating optical wave field. Design, operation and measurement results are presented. A typical application for this sensor would be in 3-D imaging (range measurement) using heterodyne interferometry. >

The lock-in CCD-two-dimensional synchronous detection of light

https://doc.rero.ch/record/8367/files/Berdondini_Luca_-_High-density_electrode_array_20071120.pdf

High-density electrode array for imaging in vitro electrophysiological activity

A complete range camera system, working with the time-of- flight principle, is introduced. This ranging system uses modulated LEDs as active illumination source and a new lock-in CCD sensor as demodulator and detector. It requires no mechanically scanning parts because every pixel of the sensor contains a lock-in amplifier, enabling both intensity and range measurement for all pixels in parallel. Two such lock-in imagers are realized in 2.0 micrometer CMOS/CCD technology, (1) a line sensor with 108 pixels and an optical fill factor of 100% and (2) a 64 X 25 pixel image sensor with 20% fill factor. The basics of time-of-flight ranging are introduced with a detailed description of the elements necessary. Shot noise limitation to ranging resolution is deduced and confirmed by simulation. An optical power budget is offered giving the relation between the number of photons in a pixel depending on the light source, the observed object, and several camera parameters. With the described lab setup, non- cooperative targets can be measured over a distance of several meters with a resolution of some centimeters.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Peter Seitz

Papers

Solid-state time-of-flight range camera

Device and method for spatially resolved photodetection and demodulation of modulated electromagnetic waves

The lock-in CCD-two-dimensional synchronous detection of light

High-density electrode array for imaging in vitro electrophysiological activity

Time-of-flight range imaging with a custom solid state image sensor