Traditional Scanners Research Articles

Mobile phone applications for 3-dimensional scanning and digital anthropometry: a precision comparison with traditional scanners.

The precision of digital anthropometry through 3-dimensional (3D) scanning has been established for relatively large, expensive, non-portable systems. The comparative performance of modern mobile applications is unclear. Forty-six adults (age: 23.3 ± 5.3 y; BMI: 24.4 ± 4.1 kg/m2) were assessed in duplicate using: (1) a mobile phone application capturing two individual 2D images, (2) a mobile phone application capturing serial images collected during a subject's complete rotation, (3) a traditional scanner with a time of flight infrared sensor collecting visual data from a subject being rotated on a mechanical turntable, and (4) a commercial measuring booth with structured light technology using 20 infrared depth sensors positioned in the booth. The absolute and relative technical error of measurement (TEM) and intraclass correlation coefficient (ICC) for each method were established. Averaged across circumferences, the absolute TEM, relative TEM, and ICC were (1) 0.9 cm, 1.5%, and 0.975; (2) 0.5 cm, 0.9%, and 0.986; (3) 0.8 cm, 1.5%, and 0.974; and (4) 0.6 cm, 1.1%, and 0.985. For total body volume, these values were (1) 2.2 L, 3.0%, and 0.978; (2) 0.8 L, 1.1%, and 0.997; (3) 0.7 L, 0.9%, and 0.998; and (4) 0.8 L, 1.1%, and 0.996, with segmental volumes demonstrating higher relative errors. A 3D scanning mobile phone application involving full rotation of subjects in front of a smartphone camera exhibited similar reliability to larger, less portable, more expensive 3D scanners. In contrast, larger errors were observed for a mobile scanning application utilizing two 2D images, although the technical errors were acceptable for some applications.

The use of artificial intelligence and deep learning reconstruction in urological computed tomography: Dose reduction at ghost level

Abstract Objective: The objective of the study is to demonstrate that with the use of artificial intelligence (AI) in computed tomography (CT), radiation doses of CT kidney-ureter-bladder (KUB) and CT urogram (CTU) can be reduced to less than that of X-ray KUB and CT KUB, respectively, while maintaining the good image quality. Materials and Methods: We reviewed all CT KUBs (n = 121) performed in September 2019 and all CTUs (n = 74) performed in December 2019 at our institution. The dose length product (DLP) of all CT KUBs and each individual phase of CTU were recorded. DLP of each scan done with new scanner (Canon Aquilion One Genesis with AiCE [CAOG]) which uses AI and deep learning reconstruction (DLR) were compared against traditional non-AI scanner (GE OPTIMA 660 [GEO-660]). We also compared DLPs of both scanners against the United Kingdom, National Diagnostic Reference Levels (NDRL) for CT. Results: One hundred and twenty-one patient’s CT KUBs and 74 patient’s CTUs were reviewed. For CT KUB group, the mean DLP of 81/121 scans done using AI/DLR scanner (CAOG) was 77.8 mGy cm (1.16 mSv), while the mean DLP of 40/121 CT KUB done with GEO-660 was 317.1 mGy cm (4.75 mSv). For CTU group, the mean DLP for 46/74 scans done using AI/DLR scanner (CAOG) was 401.9 mGy cm (6 mSv), compared to mean DLP of 1352.6 mGy cm (20.2 mSv) from GEO-660. Conclusion: We propose that CT scanners using AI/DLR method have the potential of reducing radiation doses of CT KUB and CTU to such an extent that it heralds the extinction of plain film XR KUB for follow-up of urinary tract stones. To the best of our knowledge, this is the first study comparing CT KUB and CTU doses from new scanners utilizing AI/DLR technology with traditional scanners using hybrid iterative reconstruction technology. Moreover, we have shown that this technology can markedly reduce the cumulative radiation burden in all urological patients undergoing CT examinations, whether this is CT KUB or CTU.

Automated extraction of building instances from dual-channel airborne LiDAR point clouds

With the rapid development of Light Detection And Ranging (LiDAR) systems, the novel dual-channel airborne LiDAR systems have emerged to provide more complete and precise data than traditional scanners for building instance extraction since 2013. RIEGL VQ-1560i, launched in 2016, is a state-of-the-art dual-channel LiDAR system, which is capable of capturing dense points on building rooftops and façades simultaneously, due to the unique and innovative bidirectional scanning angle. Our proposed method is the first ever to use dual-channel airborne LiDAR data for subsequent point clouds processing. The main challenges of the new LiDAR data are significant amount of points, complex data structure and multi-class targets. We proposed a preprocessing-free building instance extraction method consisting of three steps, i.e., point cloud reorganization, rasterization, and constraint-based labeling for improving the extraction performance. First, point cloud reorganization, consisting of point distribution-based slicing, coarse 3D semantic segmentation, and top-down merging, is used to reorganize point cloud scene into interrelated point groups. This greatly reduces the processing difficulty and computational burden of complex structures while removing multiple classes of non-building points. Second, we rasterize the point groups into images to further reduce computational complexity while improving processing efficiency. Finally, we utilize the upper and lower structural relationship of buildings to label them and then remap into 3D buildings. Experimental results on six test point cloud scenes demonstrate the outstanding performance of the proposed preprocessing-free method. For semantic-level performance, our method achieves 95.36% in average recall and 93.59% in average F1-score. While for instance-level performance, our approach reaches 92.86% and 98.31% in quality on two public test scenes, respectively. • Dual-channel ALS data is used to build instances extraction for the first time. • The proposed method is preprocessing-free and fully automated. • The input scene is reorganized based on point distribution and top-down merging. • Both semantic-based and instance-based building segmentation were conducted.

Camera-based OCR scene text detection issues: A review

Camera-based scene text detection and recognition is a research area that has attracted countless attention and had made noticeable progress in the area of deep learning technology, computer vision, and pattern recognition. They are highly recommended for capturing text on-scene images (signboards), documents with a multipart and complex background, images on thick books and documents that are highly fragile. This technology encourages real-time processing since handheld cameras are built with very high processing speed and internal memory, are quite easy and flexible to use than the traditional scanner whose usability is limited as they are not portable in size and cannot be used on images captured by cameras. However, characters captured by traditional scanners pose fewer computational difficulties as compared to camera captured images that are associated with divers’ challenges with consequences of high computational complexity and recognition difficulties. This paper, therefore, reviews the various factors that increase the computational difficulties of Camera-Based OCR, and made some recommendations as per the best practices for Camera-Based OCR systems.

Dual-Energy CT and Radiation Dose

As dual-energy CT scanners become more common, it is worth revisiting their benefits over conventional CT. The promises to increase the conspicuity of pathology and assist in differentiating tissue are much touted, but how can we realize the benefits of radiation dose reduction [1Grajo J.R. Sahani D.V. Dual-energy CT of the abdomen and pelvis: radiation dose considerations.J Am Coll Radiol. 2018; 15: 1128-1132Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar]? This article will briefly discuss the technology of dual-energy CT scanners, review some of the practical applications, and discuss the potential benefits and shortcomings of dose reduction. The principle behind dual-energy CT is that scanning at two different kilovoltage peaks allows determination of attenuation curves of tissue. This can be accomplished through several different methods, including fast kilovoltage switching with single-source and single-detector, dual-layer detectors with one source, or dual detectors with dual-source, or dual-detector offset 90° from each other. The spectral information can be used to generate standard CT images in addition to mono-energetic reformats (often chosen slightly higher than the k-edge of iodine to increase conspicuity of enhancement; Fig. 1), virtual noncontrast images (Fig. 2), perfusion-like imaging (iodine-only images) [2Weidman E.K. Plodkowski A.J. Halpenny D.F. et al.Dual-energy CT angiography for detection of pulmonary emboli: incremental benefit of iodine maps.Radiology. 2018; 289: 546-553Crossref PubMed Scopus (53) Google Scholar], as well as other niche benefits to identify elements by k-edge and z-effective techniques (such as uric acid in gout) [3Glazebrook K.N. Guimaraes L.S. Murthy N.S. et al.Identification of intraarticular and periarticular uric acid crystals with dual-energy CT: initial evaluation.Radiology. 2011; 261: 516-524Crossref PubMed Scopus (189) Google Scholar]. Further applications of mono-energetic selection at higher kilovoltage may allow for reduced streak artifact from beam hardening in the case of orthopedic prostheses or other hardware [4Bamberg F. Dierks A. Nikolaou K. Reiser M.F. Becker C.R. Johnson T.R. Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation.Eur Radiol. 2011; 21: 1424-1429Crossref PubMed Scopus (423) Google Scholar].Fig 2Traditional (A), virtual noncontrast (B), and iodine-only (C) reformats of a CT abdomen/pelvis with intravenous contrast. Indeterminate density right renal lesion (arrows). Circle region of interest on lesion with measurements of Area (A/Ar), Perimeter (P/Perim), Mean attenuation (M/Av), and Standard Deviation of attenuation (SD). Virtual noncontrast image shows similar density to traditional scan and iodine-only image shows no enhancement, confirming benign cyst.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Some of these benefits translate well into radiation dose reduction. The virtual noncontrast imaging at times permits removing a whole phase of imaging, as with renal or angiographic imaging. This could cut the dose in half for some studies. Furthermore, if the mono-energetic imaging is sufficient to salvage a poorly timed contrast bolus, this may spare a patient from needing to return for repeat imaging, reducing dose to the patient and delay in care. Yet, in other ways, the dual-energy CT scanner is similar to a traditional scanner. Simply substituting a dual-energy CT scanner for a conventional scanner will not reduce dose. Automatic exposure compensation works in the same way as on a traditional scanner, and though there are additional tools at the radiologist’s disposal as described previously, the intrinsic radiation exposure will be similar. The responsibility remains with the radiologist to act as steward of diagnostic medical radiation and determine if the advantages of dual-energy CT permit a dose reduction. If protocols are not adapted to remove the noncontrast phase, optimal dose savings will not be realized. If practices do not elect to reduce dose to offset the other benefits of dual-energy imaging, dose will remain the same. The responsibility falls to the radiologist to decide conscientiously how to reduce radiation dose in keeping with the principles of “as low as reasonably allowable” and the efforts of groups like Image Wisely and Image Gently. Dual-energy CT empowers us to re-assess imaging protocols in a new light and optimize patient care.

Development of a XYZ scanner for home-made atomic force microscope based on FPAA control

Abstract Atomic force microscopy (AFM) is one of the useful tools in the fields of nanoscale measurement and manipulation. High speed scanning is one of the crucial requirements for live cell imaging and soft matter characterization. The scanning speed is limited by the bandwidth of the AFM’s detection and actuation components. Generally, the bandwidth of a traditional scanner is too low to conduct the live cell imaging. This paper presents a simple and integrated compact home-made AFM for high speed imaging. To improve the bandwidth of the scanner, a parallel kinematics mechanism driven by piezoelectric actuators (PZTs) is proposed for the fast positioning in the X, Y and Z directions. The mechanical design optimization, modeling and analysis, and experimental testing have been conducted to validate the performance of the proposed scanner. A number of experimental results showed that the developed scanner has the capability for broad bandwidth with low coupling errors in the actuation directions. A hybrid control strategy including feedforward and feedback loops has been designed to significantly improve the dynamic tracking performance of the scanner and a field programmable analog array (FPAA) system is utilized to implement the control algorithm for excellent and stable tracking capability. Further, a number of high speed measurements have been conducted to verify the performance of the developed AFM.

Taking Compressive Sensing to the Hardware Level: Breaking Fundamental Radio-Frequency Hardware Performance Tradeoffs

Compressive sensing (CS) theory opens promising avenues toward building rapid and energy-efficient sensing systems in a wide range of applications that require inherently high temporal and/or spatial resolution while exhibiting a sparse signal structure [1]-[5]. The goal of this article is to review recent efforts to realize the benefits of CS in custom sensing hardware and the broad challenges that arise by investigating an example application in radio-frequency (RF) communications. We discuss in detail how using CS for the design of RF spectrum scanners can break through the fixed tradeoffs among scan time, hardware complexity, and energy consumption of traditional scanner architectures. Using the specific example of RF spectrum sensing [4], [6]-[11] we demonstrate how close collaborations between hardware and signal processing experts can yield new solutions that advance the state of the art in an important application domain. We stress the problems that arise when designing a custom hardware for CS [12]-[15] and address questions that often go beyond the currently available literature in CS, e.g., coping with the impairments of real hardware and avoiding catastrophic breakdown when the spectrum becomes nonsparse.

Implementation of 16-Channel AMR Sensor Array for Quantitative Mapping of Two-Dimension Current Distribution

Implementation of 16-Channel AMR Sensor Array for Quantitative Mapping of Two-Dimension Current Distribution

Approaches to reducing radiation dose from radionuclide myocardial perfusion imaging.

Radionuclide myocardial perfusion imaging (MPI) plays a vital role in the evaluation and management of patients with coronary artery disease. However, because of a steep growth in MPI in the mid 2000s, concerns about inappropriate use of MPI and imaging-related radiation exposure increased. In response, the professional societies developed appropriate-use criteria for MPI. Simultaneously, novel technology, image-reconstruction software for traditional scanners, and dedicated cardiac scanners emerged and facilitated the performance of MPI with low-dose and ultra-low-dose radiotracers. This paper provides a practical approach to performing low-radiation-dose MPI using traditional and novel technologies.

CT reconstruction from simultaneous projections: a step towards capturing CT in One Go

This paper focuses on minimising the time requirement for CT capture through an innovative simultaneous X-ray capture method. The state-of-the-art CT-imaging methodology captures a sequence of projections during which the internal organ movements may lead to poor reconstruction due to motion artefacts. Traditional CT scanners minimise such effects by taking extra projections. In this work, we focus on an innovative CT capture method that captures projections simultaneously, thus significantly minimises the scan time. Through ensuring rapid scan, the proposed method eliminates the extra projections that are needed to compensate for motion artefacts. By requiring a less number of projections, the simultaneous CT capture model ultimately minimises the radiation dose requirement. While the simultaneous CT capture model has already been proposed in our earlier works [Saha S, Tahtali M, Lambert A, Pickering M. 2012. Multi-axial CT reconstruction from few view projections. In: SPIE optical engineering+applications. USA: International Society for Optics and Photonics; p. 85000A–85000A and Tahtali M, Saha SK, Lambert AJ, Pickering MR. 2013. A new imaging method for real-time 3D X-ray reconstruction. In: SPIE medical imaging. International Society for Optics and Photonics; p. 86685G–86685G], in this work, we enhance the model through better initialisation along with prior smoothing before successive iterations of the iterative algorithms. We also elaborate the model considering two different X-ray source/detector configurations. For the same number of X-ray sources in total, set-up II (which considers eight angular projections) ensures better cross-section reconstruction compared to set-up I (which considers only four angular projections). In addition to simulation experiments, we present results from real experimental data from a physical 3D object, and critical analysis of the experimental findings

Dosimetric evaluation of a 256-slice computed tomography scanner

This study evaluated the effectiveness of patient dose reduction tools on a 256-slice computed tomography scanner (Brilliance iCT, Philips). The performance of the Brilliance iCT scanner was described in terms of cumulative dose and dose-normalised contrast-to-noise ratio (CNRD). The efficiency of automatic tube current modulation (Z-Dom and D-Dom), shaping filters (SmartShape and IntelliBeam) and asymmetric collimator (Eclipse) was evaluated using appropriate phantoms. The scattered radiation contribution from the peripheral regions to the cumulative dose is not negligible. The CNRD is 20 % better compared to a traditional 16-slice scanner, with a dose reduction of 40 %. The application of shaping filters decreases the dose in the peripheral regions. The application of D-Dom and Z-Dom modulations reduces the current-time product (mAs) values by 23 and 18 %, respectively, but they are not yet integrated. The over-ranging effect is not negligible, despite the use of an Eclipse asymmetric collimator. Brilliance iCT dose reduction tools are efficient, but should be analysed carefully and used correctly.

Axially Oriented Crystal Geometry Applied to Small-Animal PET System: A Proof of Concept

Improving resolution without decreasing sensitivity in positron emission tomography (PET) is of great interest for small animal studies. Traditional PET scanners use radially oriented detector block structures. This geometry implies a relationship between the spatial resolution and the sensitivity. An axially oriented crystal geometry can limit this correlation. With a fine measurement of the depth of interaction (DOI) and a continuous measurement of the axial interaction position, this axial geometry can provide high resolution and remove parallax effects. With a careful choice of the crystal and providing enough crystal elements in the radial direction, a good sensitivity can be achieved. Such improvements also allow a more accurate gamma tracking and Compton analysis of the events, indirectly increasing the sensitivity. We have proposed a PET scanner in which LYSO crystals are axially oriented and coupled at both ends by multichannel photo-detectors. The gamma interaction position is given by the hit crystals for the transverse plane and by the light spread on both photo-detectors for the axial direction. The axial position of the events is reconstructed using a calibration procedure and the transverse position is reconstructed using a clustering algorithm. In this paper, we present a complete simulation work flow, including the physical effects, the optical and electronic effects, as well as a reconstruction algorithm. A point sources phantom was used to evaluate the spatial resolutions, and a MOBY phantom was used for overall image quality evaluation. This paper shows that using four modules arranged around the animal, a volumetric spatial resolution below 1 mm3 can be achieved while keeping a detection efficiency close to 10%.

An Improved Method of USM Processing on Color Image

Unsharp masking (USM) is an image manipulation technique, the principle of which is exaggerating the lighter-darker contrast between the two sides of an edge in order to enhance the visual definition of the image. In this study, typical computer image sharpening methods and defects were studied and the sharpening principle of traditional electronic scanners was adopted to propose an improved method of USM processing, that is, regard the most significant level change in color channel as the source image of extracting so as to obtain the edge enhancement information. Thus greater edge contrast was gained when applied to all channels. Experiments on RGB and CMYK images were conducted both by conventional and enhanced methods in Matlab. The results suggest that the improved image sharpening method could enhance the contrast of the image profile and get higher image definition degree.

Using Supermarket Loyalty Card Data to Analyse the Impact of Promotions

The aim of this paper is to show how supermarket loyalty card data from a panel of over 1.4 million shoppers can be used to analyse the effect of price promotions in a way which can bring significant advantages to retailers and manufacturers when making promotional decisions. The paper demonstrates the significant advantages that loyalty card data can bring to enhance our understanding of promotions, compared to traditional scanner and panel datasets. Regression analysis is used to compare the effects of different promotional mechanics upon different tiers of product across the fresh beef category in Tesco, using both scanner data and loyalty card data. The results show that using loyalty card data, which enables us to moderate for specific shopper characteristics, produces more statistically significant results and provides a more detailed picture of how promotions influence sales.

Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging

As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30° × 30° in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users.

Convenient integrating sphere scanner for accurate luminous flux measurements

Measurement results and applications of a recently developed device for the measurement of the spatial uniformity of integrating spheres are presented. Due to the complexity of their implementation, sphere scanners are mainly used by national metrology institutes to increase the accuracy of relative and absolute luminous flux measurements (Ohno et al 1997 J. IES 26 107–14, Ohno and Daubach 2001 J. IES 30 105–15, Ohno 1998 Metrologia 35 473–8, Hovila et al 2004 Metrologia 41 407–13). The major drawback of traditional scanners for integrating spheres is the necessity of a complex and time-consuming sphere modification, as the lamp holder has to be replaced by a new scanner holder with additional cables for power supply and for communication with the stepping motor control unit (Ohno et al 1997 J. IES 26 107–14). Therefore, with traditional scanners the relative spatial sphere responsivity already changes due to the installation of a special scanner holder. The new scanner simply substitutes the lamp under test: it can be screwed into an E27 lamp socket, as it needs only two electrical contacts. Two wires are simultaneously used for the power supply of the stepping motor control unit, the scanner light source (LED) and for the signal transmission of commands and results. The benefits of scanner-assisted measurements are shown for spotlight lamp calibrations.

Integrated three-dimensional optical MEMS for chip-based fluorescence detection

This paper presents a novel fluorescence sensing chip for parallel protein microarray detection in the context of a 3-in-1 protein chip system. This portable microchip consists of a monolithic integration of CMOS-based avalanche photo diodes (APDs) combined with a polymer micro-lens, a set of three-dimensional (3D) inclined mirrors for separating adjacent light signals and a low-noise transformer-free dc–dc boost mini-circuit to power the APDs (ripple below 1.28 mV, 0–5 V input, 142 V and 12 mA output). We fabricated our APDs using the planar CMOS process so as to facilitate the post-CMOS integration of optical MEMS components such as the lenses. The APD arrays were arranged in unique circular patterns appropriate for detecting the specific fluorescently labelled protein spots in our study. The array-type APDs were designed so as to compensate for any alignment error as detected by a positional error signal algorithm. The condenser lens was used as a structure for light collection to enhance the fluorescent signals by about 25%. This element also helped to reduce the light loss due to surface absorption. We fabricated an inclined mirror to separate two adjacent fluorescent signals from different specimens. Excitation using evanescent waves helped reduce the interference of the excitation light source. This approach also reduced the number of required optical lenses and minimized the complexity of the structural design. We achieved detection floors for anti-rabbit IgG and Cy5 fluorescent dye as low as 0.5 ng/µl (∼3.268 nM). We argue that the intrinsic nature of point-to-point and batch-detection methods as showcased in our chip offers advantages over the serial-scanning approach used in traditional scanner systems. In addition, our system is low cost and lightweight.

Bariatric surgery for treatment of morbid obesity in an adolescent with Marfan syndrome

A 16 year old Caucasian female with genetically confirmed Marfan syndrome and extreme obesity (weight: 205 kg, height: 176 cm, BMI: 66 kg/m 2) was referred to Cincinnati Children's Hospital Comprehensive Weight Management Center for bariatric surgery. Her comorbidities attributed to obesity included: obstructive sleep apnea, hyperinsulinemia, hypertension, left ventricular hypertrophy, gastroesophageal reflux, urinary stress incontinence, and irregular menses. Her family history was concerning for sudden death from aortic dissections as early as the 2nd decade of life for other individuals with Marfan syndrome and concomitant severe obesity. Cardiac imaging at time of referral was limited secondary to poor acoustic windows for echocardiography and body habitus which restricted the use of traditional scanners. Initial challenges included estimating her surgical risk due to her connective tissue disease and the unknown status of her aorta. Additional cardiac Magnetic Resonance (MR) imaging demonstrated no aortic dilation. She underwent uneventful laparoscopic Roux-en-Y gastric bypass surgery and recovery. Six months later her weight had decreased to 162 kg (BMI: 52.0 kg/m 2, weight loss: 43 kg). Hyperinsulinemia improved (fasting insulin: 38.9 → 19.7 uU/ml), and left ventricular mass improved (55 → 39 g/m 2.7). This is the first case highlighting the safety and potential impact of surgical weight loss in the management of an adolescent with Marfan syndrome. Lifelong followup is recommended due to long term risks of Marfan syndrome, and independent nutritional risks of gastric bypass surgery.

Image-based 3D photography using opacity hulls

We have built a system for acquiring and displaying high quality graphical models of objects that are impossible to scan with traditional scanners. Our system can acquire highly specular and fuzzy materials, such as fur and feathers. The hardware set-up consists of a turntable, two plasma displays, an array of cameras, and a rotating array of directional lights. We use multi-background matting techniques to acquire alpha mattes of the object from multiple viewpoints. The alpha mattes are used to construct an opacity hull. The opacity hull is a new shape representation, defined as the visual hull of the object with view-dependent opacity. It enables visualization of complex object silhouettes and seamless blending of objects into new environments. Our system also supports relighting of objects with arbitrary appearance using surface reflectance fields, a purely image-based appearance representation. Our system is the first to acquire and render surface reflectance fields under varying illumination from arbitrary viewpoints. We have built three generations of digitizers with increasing sophistication. In this paper, we present our results from digitizing hundreds of models.

Novel signal-processing techniques in barcode scanning

Traditional barcode scanners use analog edge detectors to detect the boundaries of dark and light areas. As long as the edge strength exceeds a given threshold, the detected edge is considered to correspond to a bar/space boundary. Such a hard decision often leads to errors, especially in scanning barcodes that are poorly printed or scanned from a distance. An earlier study showed that much better results can be obtained by working directly with samples of the analog data. However, that method requires storing the entire sampled waveform of a scan line in memory, which is not cost effective. The method described in the article attempts to combine the performance advantages of processing the samples of the analog waveform with the low-cost advantage of the traditional methods. We still rely on edge-detection circuits, however, in addition to saving the edge time we also store information about the edge strength. In this way, we have been able to produce many of the benefits of the approach described in Joseph and Pavlidis (1993) with only a small increase in cost.