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A new formulation of 3D modeling using signal processing and calibration of individual frames is proposed. The scheme eliminates the need of the pre-knowledge of the camera position relatively to the source and the object. The experiment performed on primitive geometries and real world objects show qualitatively that the system can give up to ± 0.1 mm accuracy.
Thermal inspections of buildings contribute to detection of damaged and weak spots in the building hull. 3D spatial reference for this purpose can be achieved combining infrared images with 3D building models via texture mapping. Using terrestrial image sequences from a camera mounted in a mobile platform frontal faces can be captured, while airborne image sequences can be taken for roofs and inner...
Access to the scene irradiance is a desirable feature in many computer vision algorithms. Applications like BRDF estimation, relighting or augmented reality need measurements of the object's photometric properties and the simplest method to get them is using a camera. However, the first step necessary to achieve this goal is the computation of the function that relates scene irradiance to image intensities...
Time-of-flight range sensors have error characteristics, which are complementary to passive stereo. They provide real-time depth estimates in conditions where passive stereo does not work well, such as on white walls. In contrast, these sensors are noisy and often perform poorly on the textured scenes where stereo excels. We explore their complementary characteristics and introduce a method for combining...
Camera calibration using patterns is widely used in computer vision and industry. The accuracy of calibration depends on the accuracy of the pattern. A high accuracy pattern is usually difficult to manufacture in labs. In this paper, we propose to use two images of two identical industrial objects as natural calibration patterns. The corresponding line segments on the objects are used for a nonlinear...
Acquisition of consistent multi-camera image data such as for time-slice sequences (widely known by their use as cinematic effects, e.g. in “The Matrix”) is a challenging task, especially when using low-cost image sensors. Many different steps such as camera calibration and color conformation are involved, each of which poses individual problems. We have developed a complete and extendable setup for...
Self-calibration for imaging sensors is essential to many computer vision applications. In this paper, a novel algorithm based on multiple view self-calibration and metric reconstruction is proposed for structured light system. In the method, the camera is implemented in three different positions to acquire images. This algorithm can be applied in various occasions with its simple calculation and...
Traditionally, multi-view stereo algorithms estimate three-dimensional structure from corresponding points by linear triangulation or bundle-adjustment. This introduces systematic errors in case of inaccurate camera calibration and partial occlusion. The errors are not negligible in applications requiring high accuracy like micro-metrology or quality inspection. We show how accuracy of structure estimation...
A lens-array-based integral imaging camera is studied in this work, which consists of a lens array, a main lens and a CCD camera. The lens array is placed on the object side of the main lens, thus can provide wider stereo baseline than other lens-array-based integral imaging cameras where the lens array is usually placed on the sensor side. However, the image captured by this system presents severe...
A robust model-based calibration method for dual laser line active triangulation range cameras, with the goal of reducing camera occlusion via data fusion, is presented. The algorithm is split into two stages: line-based estimation of the lens distortion parameters in the individual cameras, and computation of the perspective transformation from each image to a common world frame in the laser plane...
In the distortion correction of camera lens, the methods employed to estimate the center of distortion are either complicated or requiring device to measure coordinates with high precision. By analyzing the geometric characters of circles with radial distortion, we find that the center of distortion must lies on the line which goes through every center of the distorted concentric circles. In this...
To find the corresponding target points among multi-images of the same scene is a premise of three dimensional (3D) reconstruction automatically from multi-view images. The geometrical constraints among multi-images of the same scene are analyzed and it is concluded that the error matching cannot be removed if only using 2D information. In this paper, we present an iterative fractional step matching...
Interest point-based multiview 3D reconstruction and calibration methods have been very successful in select applications but are not applicable when an abundance of feature points are not available. They also lead to an unorganized point cloud reconstruction where the geometry of the scene is not explicit. The multiview stereo methods on the other hand yield dense surface geometry but require a highly...
In this paper we present a method to calibrate the extrinsic parameters of a monocular camera on a moving vehicle. The method is based on a homography between two camera shots. Therefore, only the road surface has to be visible in the pair of images. A reasonable definition of the vehicle coordinate system in combination with the use of epipolar geometry reduces the complexity to parameterize the...
This paper presents a novel approach for matching 2D points between a video projector and a digital camera. Our method is motivated by camera-projector applications for which the projected image needs to be warped to prevent geometric distortion. Since the warping process often needs geometric information on the 3D scene that can only be obtained from triangulation, we propose a technique for matching...
The position of a world point's solar shadow depends on its geographical location, the geometrical relationship between the orientation of the sunshine and the ground plane where the shadow casts. This paper investigates the property of solar shadow trajectories on a planar surface and shows that camera parameters, latitude, longitude can be estimated from two observed shadow trajectories. Our contribution...
In Surveillance system usually look for the color or edge of an object in order to identify its key features, and this leads us to the key topic of geometric detection algorithms. For spatial calibration method in this thesis, the ellipse is used as the calibration target object. The method proposed by this paper applies fuzzy logic to the image pre-processing, and then links adjacent objects within...
The objective of this paper is to propose a robust one shot structured light pattern for real time 3D shape inspection system. To reduce the influence of inspected part reflectance property and ambient light, the pattern is constructed by using monochromatic light. The corner of the chessboard is utilized as the primitive of the pattern since it can provide highly accurate position. Additionally,...
In this paper we present a novel technique to calibrate multiple casually aligned projectors on a fiducial-free cylindrical curved surface using a single camera. We impose two priors to the cylindrical display: (a) cylinder is a vertically extruded surface; and (b) the aspect ratio of the rectangle formed by the four corners of the screen is known. Using these priors, we can estimate the display's...
We present a novel technique for calibrating display-camera systems from reflections in the user's eyes. Display-camera systems enable a range of vision applications that need controlled illumination, including 3D object reconstruction, facial modeling and human computer interaction. One important issue, though, is the geometric calibration of the display, which requires additional hardware and tedious...
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