Camera Platform Research Articles

Real-time auto white balancing for digital cameras using discrete wavelet transform-based scoring

In digital cameras, the process of making white colors to appear as white under different illuminants is referred to as auto white balancing. This paper presents an auto white balancing algorithm, named discrete wavelet transform (DWT)-based scoring, which is computationally much more efficient than the original auto white balancing scoring algorithm. Its computational efficiency is thus utilized to achieve a real-time implementation on an actual digital camera platform. The platform consists of the Texas Instruments TMS320DM320 programmable processor which is specifically designed for the digital camera market. The real-time implementation results indicate the effectiveness of this algorithm in identifying a scene illuminant as compared to the widely used gray-world auto white balancing algorithm.

AN INERTIALLY STABILISED VEHICLE CAMERA SYSTEM FOR DRIVER ASSISTANCE APPLICATIONS

A major task in today's automotive industry is the enhancement of comfort and safety. Thus driver assistance systems are a current topic in research and development. As assistance systems based on image processing facilitate a wide range of applications, camera systems in vehicles become necessary. This report presents an inertially stabilised camera platform for use in vehicles. First experiments during test drives are described using the presented system in combination with a lane tracking algorithm. However, being a universal platform for different purposes, a large number of future applications can be realised based on the described system.

Global alignment of sensor positions with noisy motion measurements

We investigate the global alignment of some 3-D spatial points, knowing the motion between pairwise nearby positions. A common application is to determine the trajectory of a mobile vision-based system from the scene images acquired along its track. Exploiting redundant measurements and the rigid body motion constraint as the observation model, we apply the mixed adjustment model paradigm to develop recursive estimation algorithms under various scenarios. Results of experiments are given to demonstrate the performance for different noise levels in the observations and the improvements in the position estimation. We also present the results of an experiment with underwater images in the construction of the camera platform trajectory.

Portable real-time homecare system design with digital camera platform

An ideal homecare system needs to process multiple diagnostic signals using a portable battery-driven device and provide a real-time audio/video interface for telemedicine applications. In this paper, we present a low cost real-time homecare system based on a commercial digital camera platform. In addition to the typical multimedia recording functions of a digital camera, such as JPEG and MPEG-1/MPEG-4 recording, the proposed system can further process and compress phonocardiogram (PCG) signal concurrently.

The powered parachute as an archaeological aerial reconnaissance vehicle

AbstractThe need for a cost‐effective method of aerial archaeology that could combine the ability to acquire large‐scale, low‐altitude photographs of archaeological sites with the capacity for surveying large geographical areas led to an evaluation of the powered parachute (PPC), a type of ultralight aircraft, as an archaeological aerial reconnaissance vehicle. The suitable performance of the aircraft during flight was the first consideration, and an assessment of drift, in‐flight stability and altitude stability of the PPC proved satisfactory. Next, characteristics required of an aerial camera platform, such as slow speed, low vibration, the ability to capture images at low altitudes, portability, low cost, safety and others were considered. The PPC easily fulfilled each of the requirements. Limitations on the use of the PPC include obscuring vegetation, inclement weather and government regulations. Despite the limitations, the PPC serves as an invaluable addition to the choice of options available for aerial archaeologists. The PPC has experienced success in acquiring digital still images, digital video and thermal images at sites in Louisiana, Mississippi and North Dakota, and these promising results have led to an increased interest in this approach from archaeologists, land managers and others working in the USA and in Europe. Copyright © 2005 John Wiley & Sons, Ltd.

Photo Mosaics In Shallow Water Environments:Challenges And Results

Photo mosaics of underwater sites are useful for interpreting sites and increasing the level of detail for areas too large for conventional photography. While this tool has been used for years at deep-water sites using camera platforms, such traditional devices are difficult to use in areas that are too shallow or too rough to maintain a consistent distance to the site. In addition, some sites, notably large shipwrecks, cannot be photographed at a well-maintained distance given the time constraints of many projects. Finding alternative methods to collect data and create photo mosaics is necessary.

都市屋外および半屋外空間における短波長分光放射環境の実測

This paper presents actual condition of spectral environment in urban outdoor space as represented by canopy space surrounded by building walls, and in urban semi-outdoor space as represented by glass-enclosed atrium. Measurement surveys are made with spectroradiometer which can measure 350-2500nm spectrum continuously, and with electric camera platform which can scan over the sky. Measurement result is that near-infrared region figure in canopy space, ultraviolet-visible region figure in atrium contrastively. Especially, in Oasis 21 covered glazed roof with water pond, solar radiation of near-infrared region is reduced drastically by spectral selectivity of water.

A review of low-level aerial archaeology and its application in Australia

This paper examines methods of low-level aerial archaeology and provides a rationale for utilizing these systems more widely in Australian archaeological projects. While the value of conventional aerial archaeology is apparent, different low-level aerial photographic methods can be employed more comprehensively by archaeologists to document, interpret and monitor sites in Australia. Kite, balloon, boom and other low-altitude remotely controlled camera platforms are rarely applied in Australian archaeology despite the fact that archaeologists overseas have used these aerial imaging platforms for decades. Unmanned Aerial Vehicles (UAVs) and more conventional wireless remote sensing image technology will be used more consistently in the next decades to reconstruct and reinterpret the landscape of the past.

Wireless tele‐operated mechatronic control system for camera platform positioning

The skill of the camera operator in controlling the orientation of camera platforms in the film industry is one of the crucial factors in producing movies with good cinematography. Some film footage requires landscapes that make it difficult for the camera operator to efficiently operate the camera platform. Tether connections limit the manner in which the camera platform can be mounted in order to achieve the best scene shooting. This paper reports on the project undertaken by the Mechatronics and Robotics Research Group at Massey University, in conjunction with the New Zealand film industry, on the development of wireless control camera platforms.

Robonaut: a robot designed to work with humans in space.

The Robotics Technology Branch at the NASA Johnson Space Center is developing robotic systems to assist astronauts in space. One such system, Robonaut, is a humanoid robot with the dexterity approaching that of a suited astronaut. Robonaut currently has two dexterous arms and hands, a three degree-of-freedom articulating waist, and a two degree-of-freedom neck used as a camera and sensor platform. In contrast to other space manipulator systems, Robonaut is designed to work within existing corridors and use the same tools as space walking astronauts. Robonaut is envisioned as working with astronauts, both autonomously and by teleoperation, performing a variety of tasks including, routine maintenance, setting up and breaking down worksites, assisting crew members while outside of spacecraft, and serving in a rapid response capacity.

Robotic surgery, telerobotic surgery, telepresence, and telementoring. Review of early clinical results.

Although laparoscopic cholecystectomy rapidly became the standard of care for the surgical treatment of cholelithiasis, very few other abdominal or cardiac operations are currently performed using minimally invasive surgical techniques. The inherent limitations of traditional laparoscopic surgery make it difficult to perform these operations. We, and others, have attempted to use robotic technology to (a) provide a stable camera platform, (b) replace two-dimensional with three-dimensional (3-D) imaging, (c) simulate the fluid motions of a surgeon's wrist to overcome the motion limitations of straight laparoscopic instruments, and (d) offer the surgeon a comfortable, ergonomically optimal operating position. In this article, we review the early published clinical experience with surgical robotic and telerobotic systems and assess their current limitations. The voice-controlled AESOP robot replaces the cameraperson and facilitates the performance of solo-surgeon laparoscopic operations. AESOP provides a stable camera platform and avoids motion sickness in the operative team. The telerobotic Zeus and da Vinci surgical systems permit solo surgery by a surgeon from a remote sight. These telerobots hold the camera, replace the surgeon's two hands with robotic instruments, and serve in a master-slave relationship for the surgeon. Their robotic instruments simulate the motions of the surgeon's wrist, facilitating dissection. Both telerobots use 3-D imaging to immerse the surgeon in a three-dimensional video operating field. These robots also provide operating positions for the surgeon console that are ergonomically superior to those required by traditional laparoscopy. The technological advances of these telerobots now permit telepresence surgery from remote locations, even locations thousands of miles away. In addition, telepresence permits the telementoring of novice surgeons who are performing new procedures by expert surgeons in remote locations. The studies reviewed here indicate that robotics and telerobotics offer potential solutions to the inherent problems of traditional laparoscopic surgery, as well as new possibilities for telesurgery and telementoring. Nonetheless, these technologies are still in an early stage of development, and each device entails its own set of challenges and limitations for actual use in clinical settings.

The pitfalls of laparoscopic surgery: challenges for robotics and telerobotic surgery.

After its debut in 1988, laparoscopic cholecystectomy rapidly became the standard of care for cholelithiasis, yet very few surgeons use minimally invasive techniques for other abdominal operations. Why do most surgeons continue to perform traditional open gastrointestinal operations? We believe that the answer to this question lies in the fact that advanced laparoscopic operations are difficult to learn, perform, and master. A number of inherent pitfalls of laparoscopy hinder the performance of these operations even after the surgeon has accumulated years of experience. These pitfalls include an unstable video camera platform, limited motion (degrees of freedom) of straight laparoscopic instruments, two-dimensional imaging, and poor ergonomics for the surgeon. Inexperienced or bored laparoscopic camera-holders move the camera frequently and rotate it away from the horizon. The long, straight laparoscopic instruments are limited in their motion by the fixation enforced by the abdominal wall trocars. Similarly, the standard two-dimensional video imaging used in most laparoscopic operations impedes the surgeon's depth perception, compounding the limitations of laparoscopic instruments. In addition, surgeons are forced to assume ergonomically awkward stances in performing many laparoscopic operations. These four factors hinder a surgeon's efforts to learn and to perform advanced laparoscopic operations, significantly lengthening the learning curve. The articles presented in this issue suggest that robotics and telerobotics offer solutions to these nagging pitfalls of laparoscopic surgery.

Indoor Scene Reconstruction from Sets of Noisy Range Images

This paper describes a system for building 3D models of indoor scenes from sets of noisy laser range images. It addresses several important aspects of this problem, namely, preprocessing, which includes image segmentation and planar model fitting; view registration, which is the method of determining the rigid transformation that describes the relative pose of the camera platform between views; and reconstruction, which is the subsequent integration or fusion of separate range images into a single 3D model. Our proposed strategy is to use a statistical sensor model. We thus account for noise properties of the data at each stage in the reconstruction process, which produces reliable results even in the presence of significant measurement noise. We give an empirical analysis of a plane-based registration method and present results using real range data that demonstrate the performance of the entire reconstruction system.

The specific character of limit errors in close range photogrammetry

Close-range photogrammetry is to determine the shape and size of the object, instead of it's absolute position. Therefore, at first, any translation and rotation of the photogrammetric model of the object caused by whole geodesic, photographic and photogrammetric procedures in close-range photogrammetry could not be considered. However, it is necessary to analyze all the reasons which cause the deformations of the shape and size and to present their corresponding theories and equations. This situation, of course, is very different from the conventional topophotogrammetry. In this paper some specific characters of limit errors in close-range photogrammetry are presented in detail, including limit errors for calibration of interior elements for close-range cameras, the limit errors of relative and absolute orientations in close-range cameras, the limit errors of relative and absolute orientations in close-range photogrammetric procedures, and the limit errors of control works in close-range photogrammetry. A theoretical equation of calibration accuracy for close-range camerais given. Relating to the three examples in this paper, their theoretical accuracy requirement of interior elements of camera change in the scope of ±(0.005–0.350) mm. This discussion permits us to reduce accuracy requirement in calibration for an object with small relief, but the camera platform is located in violent vibration environment. Another theoretical equation of relative RMS of base lines (mS/S) and the equation RMS of start direction are also presented. It is proved that themS/S could be equal to the relative RMS ofmΔX/ΔX. It is also proved that the permitting RMS of start direction is much bigger than the traditionally used one. Some useful equations of limit errors in close-range photogrammetry are presented as well. Suggestions mentioned above are perhaps beneficial for increasing efficiency, for reducing production cost.

Rotation and direction judgment from visual images head-slaved in two and three degrees-of-freedom.

The contribution to spatial awareness of adding a roll degree-of-freedom (DOF) to telepresence camera platform yaw and pitch was examined in an experiment where subjects judged direction and rotation of stationary target markers in a remote scene. Subjects viewed the scene via head-slaved camera images in a head-mounted display. Elimination of the roll DOF affected rotation judgment, but only at extreme yaw and pitch combinations, and did not affect azimuth and elevation judgement. Systematic azimuth overshoot occurred regardless of roll condition. Observed rotation misjudgments are explained by kinematic models for eye-head direction of gaze.

A vessel-towed camera platform for surveying seafloor habitats of the continental shelf

A vessel-towed camera platform with unique design features, developed to photograph seafloor habitat types on the continental shelf off southeastern Australia, is described. Photographic images contributed to the evaluation of the importance of habitat types to demersal fishery productivity. The significant features of the towed automatically compensating observation system (TACOS) are: it is a towed system that enables collection of photographic data along transects of several kilometres in length; it provides real-time video to the ship which permits fine operational control and real-time capture of images and data; it maintains a constant height above the bottom, and can traverse a range of bottom types including high-relief reefs. It is a low-cost system, relative to remotely operated vehicles (ROVs) or submersible camera platforms, based on an easily fabricated framework and commercially available components. The system has been successfully field tested to depths of 190 m in exposed open-ocean conditions.

Application and Accuracy of Two Fixed Base Camera Systems

This paper discusses the application of two fixed base non‐metric camera systems. The first is a helicopter supported 5m boom carrying two 70 mm Hasselblad cameras, fired simultaneously. The 1;850 scale stereomodels, each covering about 40 ×45 m, were used to measure individual tree characteristics, such as crown closure and size. The second system is a portable camera platform designed for microtopography, which used sequential Minolta 35mm photography (1;80 scale) for generating DEMs and computing volume of soil erosion. In both cases, an analytical plotter was used to collect measurements without ground control. With the helicopter boom system, distances and heights were measured to within 5 per cent of true dimensions. With the portable platform system, volume estimates were within 1 per cent of field measurement values. Particular attention is given to the orientation and scaling of stereopairs. Because the air base is used to scale the model, errors in scale due to non‐parallel lines of sight are avoided. Advantages and disadvantages of both systems are discussed.

Transparent telepresence research

This article outlines some of the recent telepresence and teleoperation work being carried out in the Transparent Telepresence Research Group at the University of Strathclyde. Teleoperation work involving remotely operated vehicles, remote sensor platforms, and remote manipulators is described. The implementation of head slaved monoscopic and stereoscopic camera platforms, binaural microphone and pinnae systems, and image and audio processing with integrated virtual reality is discussed. The most recent medium for long distance communication used by the group has been, uniquely, cellular mobile phone technology. The implications of using this very low bit‐rate communication method are discussed.

Modeling and copying human head movements

Derives two discrete motion models for three-dimensional (3-D) pose recovery starting from the stochastic differential equations that describe the object's motion in continuous time. The velocity is considered first as a Wiener process, which underlies the very often used constant velocity model, and second as an Ornstein-Uhlenbeck process. Analysis of the autocorrelation signal derived in experiment from visual tracking of both translational and rotational movements of a human head demonstrates that such muscular motion is better suited to modeling by the Ornstein-Uhlenbeck velocity process. The model is embedded in an iterated extended Kalman filter, which linearizes about the predicted pose and in which care is taken properly to transform the state covariance, and incorporated in a system able visually to recover and track the pose of a human operator's head. The pose is copied onto a slave electromechanical stereo camera platform alone, providing two rotational degrees of freedom, or onto the same head carried by a robot arm to give complete six degree-of-freedom mapping of the operator's movements. Accuracy and frequency response are assessed.

Measuring Trail Erosion with a 35 mm Camera

A simple photogrammetric system was designed to monitor trail degradation by generating digital terrain models (DTMs) of sample plots <4m2. A sloped path was photographed in stereo with a standard 35 mm camera from 2.4 m above the ground. A portable stereo camera platform provided the photogrammetric parameters to capture elevation data directly off the photographs with an accuracy of about 3 mm, without the aid of ground control. Volume estimates of simulated trail erosion, computed from the photo-based DTMs, were accurate to about one percent of the true volume.