共查询到20条相似文献,搜索用时 31 毫秒
1.
Implicit Surface-Based Geometric Fusion 总被引:1,自引:0,他引:1
A. Hilton A.J. Stoddart J. Illingworth T. Windeatt 《Computer Vision and Image Understanding》1998,69(3):273-291
This paper introduces a general purpose algorithm for reliable integration of sets of surface measurements into a single 3D model. The new algorithm constructs a single continuous implicit surface representation which is the zero-set of a scalar field function. An explicit object model is obtained using any implicit surface polygonization algorithm. Object models are reconstructed from both multiple view conventional 2.5D range images and hand-held sensor range data. To our knowledge this is the first geometric fusion algorithm capable of reconstructing 3D object models from noisy hand-held sensor range data.This approach has several important advantages over existing techniques. The implicit surface representation allows reconstruction of unknown objects of arbitrary topology and geometry. A continuous implicit surface representation enables reliable reconstruction of complex geometry. Correct integration of overlapping surface measurements in the presence of noise is achieved using geometric constraints based on measurement uncertainty. The use of measurement uncertainty ensures that the algorithm is robust to significant levels of measurement noise. Previous implicit surface-based approaches use discrete representations resulting in unreliable reconstruction for regions of high curvature or thin surface sections. Direct representation of the implicit surface boundary ensures correct reconstruction of arbitrary topology object surfaces. Fusion of overlapping measurements is performed using operations in 3D space only. This avoids the local 2D projection required for many previous methods which results in limitations on the object surface geometry that is reliably reconstructed. All previous geometric fusion algorithms developed for conventional range sensor data are based on the 2.5D image structure preventing their use for hand-held sensor data. Performance evaluation of the new integration algorithm against existing techniques demonstrates improved reconstruction of complex geometry. 相似文献
2.
Abstract. Automatic acquisition of CAD models from existing objects requires accurate extraction of geometric and topological information
from the input data. This paper presents a range image segmentation method based on local approximation of scan lines. The
method employs edge models that are capable of detecting noise pixels as well as position and orientation discontinuities
of varying strengths. Region-based techniques are then used to achieve a complete segmentation. Finally, a geometric representation
of the scene, in the form of a surface CAD model, is produced. Experimental results on a large number of real range images
acquired by different range sensors demonstrate the efficiency and robustness of the method.
Received: 1 August 2000 / Accepted: 23 January 2002
Correspondence to: I. Khalifa 相似文献
3.
4.
Reconstructing a textured CAD model of an urban environment using vehicle-borne laser range scanners and line cameras 总被引:2,自引:0,他引:2
Abstract. In this paper, a novel method is presented for generating a textured CAD model of an outdoor urban environment using a vehicle-borne
sensor system. In data measurement, three single-row laser range scanners and six line cameras are mounted on a measurement
vehicle, which has been equipped with a GPS/INS/Odometer-based navigation system. Laser range and line images are measured
as the vehicle moves forward. They are synchronized with the navigation system so they can be geo-referenced to a world coordinate
system. Generation of the CAD model is conducted in two steps. A geometric model is first generated using the geo-referenced
laser range data, where urban features, such as buildings, ground surfaces, and trees are extracted in a hierarchical way.
Different urban features are represented using different geometric primitives, such as a planar face, a triangulated irregular
network (TIN), and a triangle. The texture of the urban features is generated by projecting and resampling line images onto
the geometric model. An outdoor experiment is conducted, and a textured CAD model of a real urban environment is reconstructed
in a full automatic mode. 相似文献
5.
Surface reconstruction from cross-sectional data is important in a variety of applications. It is usually possible to generate
a surface in many ways, but only reasonable ones are acceptable. A surface of minimal area has been considered as one of the
most natural optimal criteria for the original tiling method of surface reconstruction from cross sections. In the paper,
we consider minimal surfaces for continuous generalization of the tiling approach and in the general situation of reconstruction
from cross sections. We show that in these cases the minimal area criterion leads to defective surfaces and is thus unacceptable.
Published online: 23 July 2002
Correspondence to: D. Berzin 相似文献
6.
A compact algorithm for rectification of stereo pairs 总被引:32,自引:0,他引:32
Abstract. We present a linear rectification algorithm for general, unconstrained stereo rigs. The algorithm takes the two perspective
projection matrices of the original cameras, and computes a pair of rectifying projection matrices. It is compact (22-line
MATLAB code) and easily reproducible. We report tests proving the correct behavior of our method, as well as the negligible decrease
of the accuracy of 3D reconstruction performed from the rectified images directly.
Received: 25 February 1999 / Accepted: 2 March 2000 相似文献
7.
Abstract. This paper describes an unsupervised algorithm for estimating the 3D profile of potholes in the highway surface, using structured
illumination. Structured light is used to accelerate computation and to simplify the estimation of range. A low-resolution
edge map is generated so that further processing may be focused on relevant regions of interest. Edge points in each region
of interest are used to initialise open, active contour models, which are propagated and refined, via a pyramid, to a higher
resolution. At each resolution, internal and external constraints are applied to a snake; the internal constraint is a smoothness
function and the external one is a maximum-likelihood estimate of the grey-level response at the edge of each light stripe.
Results of a provisional evaluation study indicate that this automated procedure provides estimates of pothole dimension suitable
for use in a first, screening, assessment of highway condition.
Received: 9 October 1998 / Accepted: 22 February 2000 相似文献
8.
A bin picking system based on depth from defocus 总被引:3,自引:0,他引:3
It is generally accepted that to develop versatile bin-picking systems capable of grasping and manipulation operations, accurate
3-D information is required. To accomplish this goal, we have developed a fast and precise range sensor based on active depth from defocus (DFD). This sensor is used in conjunction with a three-component vision system, which is able to recognize and evaluate the
attitude of 3-D objects. The first component performs scene segmentation using an edge-based approach. Since edges are used
to detect the object boundaries, a key issue consists of improving the quality of edge detection. The second component attempts
to recognize the object placed on the top of the object pile using a model-driven approach in which the segmented surfaces
are compared with those stored in the model database. Finally, the attitude of the recognized object is evaluated using an
eigenimage approach augmented with range data analysis. The full bin-picking system will be outlined, and a number of experimental
results will be examined.
Received: 2 December 2000 / Accepted: 9 September 2001
Correspondence to: O. Ghita 相似文献
9.
Registration of technical drawings and calibrated images for industrial augmented reality 总被引:1,自引:0,他引:1
Despite tremendous progress in 3D modelling technology, most sites in traditional industries do not have a computer model
of their facilities at their disposal. In these industries, 2D technical drawings are typically the most commonly used documents.
In many cases, a database of fully calibrated and oriented photogrammetric images of parts of the plant is also available.
These images are often used for metric measurement and 3D as-built modelling. For planning revamps and maintenance, it is
necessary to use industrial drawings as well as images and 3D models represented in a common “world” coordinate system. This
paper proposes a method for full integration of technical drawings, calibrated images and as-built 3D models. A new algorithm
is developed in order to use only a few correspondences between points on a technical drawing and multiple images to estimate
a metric planar transformation between the drawing and the world coordinate system. The paper describes the mathematical relationship
between this transformation and the set of homographies needed for merging the technical drawing with all the calibrated images.
The method is implemented and fully integrated into an industrial software we developed for 3D as-built reconstruction. We
present examples of a real application, in which the method is successfully applied to create an augmented reality representation
of a waste water plant.
Accepted: 13 August 2001 相似文献
10.
This paper presents an algorithm for simultaneously fitting smoothly connected multiple surfaces from unorganized measured
data. A hybrid mathematical model of B-spline surfaces and Catmull–Clark subdivision surfaces is introduced to represent objects
with general quadrilateral topology. The interconnected multiple surfaces are G
2 continuous across all surface boundaries except at a finite number of extraordinary corner points where G
1 continuity is obtained. The algorithm is purely a linear least-squares fitting procedure without any constraint for maintaining
the required geometric continuity. In case of general uniform knots for all surfaces, the final fitted multiple surfaces can
also be exported as a set of Catmull–Clark subdivision surfaces with global C
2 continuity and local C
1 continuity at extraordinary corner points.
Published online: 14 May 2002
Correspondence to: W. Ma 相似文献
11.
Farzin Mokhtarian 《Machine Vision and Applications》1997,10(3):87-97
A complete and practical system for occluded object recognition has been developed which is very robust with respect to noise
and local deformations of shape (due to weak perspective distortion, segmentation errors and non-rigid material) as well as
scale, position and orientation changes of the objects. The system has been tested on a wide variety of free-form 3D objects.
An industrial application is envisaged where a fixed camera and a light-box are utilized to obtain images. Within the constraints
of the system, every rigid 3D object can be modeled by a limited number of classes of 2D contours corresponding to the object's
resting positions on the light-box. The contours in each class are related to each other by a 2D similarity transformation.
The Curvature Scale Space technique [26, 28] is then used to obtain a novel multi-scale segmentation of the image and the model contours. Object indexing [16, 32, 36] is used to narrow down the search space. An efficient local matching algorithm is utilized to select the best
matching models.
Received: 5 August 1996 / Accepted: 19 March 1997 相似文献
12.
Automatic high-resolution optoelectronic photogrammetric 3D surface geometry acquisition system 总被引:1,自引:0,他引:1
A fast, high-resolution, automatic, non-contact 3D surface geometry measuring system using a photogrammetric optoelectronic
technique based on lateral-photoeffect diode detectors has been developed. Designed for the acquisition of surface geometries
such as machined surfaces, biological surfaces, and deformed parts, the system can be used in design, manufacturing, inspection,
and range finding. A laser beam is focused and scanned onto the surface of the object to be measured. Two cameras in stereo
positions capture the reflected light from the surface at 10 kHz. Photogrammetric triangulation quickly transforms the pair
of 2D signals created by the camera detectors into 3D coordinates of the light spot. Because only one small spot on the object
is illuminated at a time, the stereo correspondence problem is solved in real time. The resolution is determined by a 12-bit
A/D converter and can be improved up to 25 60025 600 by oversampling. The irregular 3D data can be regularized for use with image-based algorithms.
Received: 8 October 1996 / Accepted: 3 February 1997 相似文献
13.
Optimized triangle mesh reconstruction from unstructured points 总被引:3,自引:1,他引:3
A variety of approaches have been proposed for polygon mesh reconstruction from a set of unstructured sample points. Suffering
from severe aliases at sharp features and having a large number of unnecessary faces, most resulting meshes need to be optimized
using input sample points in a postprocess. In this paper, we propose a fast algorithm to reconstruct high-quality meshes
from sample data. The core of our proposed algorithm is a new mesh evaluation criterion which takes full advantage of the
relation between the sample points and the reconstructed mesh. Based on our proposed evaluation criterion, we develop necessary
operations to efficiently incorporate the functions of data preprocessing, isosurface polygonization, mesh optimization and
mesh simplification into one simple algorithm, which can generate high-quality meshes from unstructured point clouds with
time and space efficiency.
Published online: 28 January 2003
Correspondence to: Y.-J. Liu 相似文献
14.
Motion detection with nonstationary background 总被引:4,自引:0,他引:4
Abstract. This paper proposes a new background subtraction method for detecting moving foreground objects from a nonstationary background.
While background subtraction has traditionally worked well for a stationary background, the same cannot be implied for a nonstationary
viewing sensor. To a limited extent, motion compensation for the nonstationary background can be applied. However, in practice,
it is difficult to realize the motion compensation to sufficient pixel accuracy, and the traditional background subtraction
algorithm will fail for a moving scene. The problem is further complicated when the moving target to be detected/tracked is
small, since the pixel error in motion that is compensating the background will subsume the small target. A spatial distribution
of Gaussians (SDG) model is proposed to deal with moving object detection having motion compensation that is only approximately
extracted. The distribution of each background pixel is temporally and spatially modeled. Based on this statistical model,
a pixel in the current frame is then classified as belonging to the foreground or background. For this system to perform under
lighting and environmental changes over an extended period of time, the background distribution must be updated with each
incoming frame. A new background restoration and adaptation algorithm is developed for the nonstationary background. Test
cases involving the detection of small moving objects within a highly textured background and with a pan-tilt tracking system
are demonstrated successfully.
Received: 30 July 2001 / Accepted: 20 April 2002
Correspondence to: Chin-Seng Chau 相似文献
15.
Adrian Hilton Daniel Beresford Thomas Gentils Raymond Smith Wei Sun John Illingworth 《The Visual computer》2000,16(7):411-436
In this paper a new technique is introduced for automatically building recognisable, moving 3D models of individual people.
A set of multiview colour images of a person is captured from the front, sides and back by one or more cameras. Model-based
reconstruction of shape from silhouettes is used to transform a standard 3D generic humanoid model to approximate a person's
shape and anatomical structure. Realistic appearance is achieved by colour texture mapping from the multiview images. The
results show the reconstruction of a realistic 3D facsimile of the person suitable for animation in a virtual world. The system
is inexpensive and is reliable for large variations in shape, size and clothing. This is the first approach to achieve realistic
model capture for clothed people and automatic reconstruction of animated models. A commercial system based on this approach
has recently been used to capture thousands of models of the general public. 相似文献
16.
Location is one of the most important elements of context in ubiquitous computing. In this paper we describe a location model, a spatial-aware communication model and an implementation of the models that exploit location for processing and communicating context. The location model presented describes a location
tree, which contains human-readable semantic and geometric information about an organisation and a structure to describe the
current location of an object or a context. The proposed system is dedicated to work not only on more powerful devices like
handhelds, but also on small computer systems that are embedded into everyday artefact (making them a digital artefact). Model and design decisions were made on the basis of experiences from three prototype setups with several applications,
which we built from 1998 to 2002. While running these prototypes we collected experiences from designers, implementers and users and formulated them as guidelines in this paper. All the prototype applications heavily use location information for providing their functionality. We found
that location is not only of use as information for the application but also important for communicating context. In this
paper we introduce the concept of spatial-aware communication where data is communicated based on the relative location of
digital artefacts rather than on their identity.
Correspondence to: Michael Biegl, Telecooperation Office (TecO), University of Karlsruhe, Vincenz-Prieβritz-Str. 1 D-76131 Karlsruhe, Germany.
Email: michael@teco.edu 相似文献
17.
Towards robust multi-cue integration for visual tracking 总被引:13,自引:1,他引:13
Abstract. Even though many of today's vision algorithms are very successful, they lack robustness, since they are typically tailored
to a particular situation. In this paper, we argue that the principles of sensor and model integration can increase the robustness
of today's computer-vision systems substantially. As an example, multi-cue tracking of faces is discussed. The approach is
based on the principles of self-organization of the integration mechanism and self-adaptation of the cue models during tracking.
Experiments show that the robustness of simple models is leveraged significantly by sensor and model integration. 相似文献
18.
Using vanishing points for camera calibration and coarse 3D reconstruction from a single image 总被引:5,自引:0,他引:5
In this paper, we show how to calibrate a camera and to recover the geometry and the photometry (textures) of objects from
a single image. The aim of this work is to make it possible walkthrough and augment reality in a 3D model reconstructed from
a single image. The calibration step does not need any calibration target and makes only four assumptions: (1) the single
image contains at least two vanishing points, (2) the length (in 3D space) of one line segment (for determining the translation
vector) in the image is known, (3) the principle point is the center of the image, and (4) the aspect ratio is fixed by the
user. Each vanishing point is determined from a set of parallel lines. These vanishing points help determine a 3D world coordinate
system R
o. After having computed the focal length, the rotation matrix and the translation vector are evaluated in turn for describing
the rigid motion between R
o and the camera coordinate system R
c. Next, the reconstruction step consists in placing, rotating, scaling, and translating a rectangular 3D box that must fit
at best with the potential objects within the scene as seen through the single image. With each face of a rectangular box,
a texture that may contain holes due to invisible parts of certain objects is assigned. We show how the textures are extracted
and how these holes are located and filled. Our method has been applied to various real images (pictures scanned from books,
photographs) and synthetic images. 相似文献
19.
Abstract. In this paper, we present a system that was developed for the European Space Agency (ESA) for the support of planetary exploration.
The system that is sent to the planetary surface consists of a rover and a lander. The lander contains a stereo head equipped
with a pan-tilt mechanism. This vision system is used both for modeling the terrain and for localization of the rover. Both
tasks are necessary for the navigation of the rover. Due to the stress that occurs during the flight, a recalibration of the
stereo-vision system is required once it is deployed on the planet. Practical limitations make it unfeasible to use a known
calibration pattern for this purpose; therefore, a new calibration procedure had to be developed that could work on images
of the planetary environment. This automatic procedure recovers the relative orientation of the cameras and the pan and tilt
axes, as well as the exterior orientation for all the images. The same images are subsequently used to reconstruct the 3-D
structure of the terrain. For this purpose, a dense stereo-matching algorithm is used that (after rectification) computes
a disparity map. Finally, all the disparity maps are merged into a single digital terrain model. In this paper, a simple and
elegant procedure is proposed that achieves that goal. The fact that the same images can be used for both calibration and
3-D reconstruction is important, since, in general, the communication bandwidth is very limited. In addition to navigation
and path planning, the 3-D model of the terrain is also used for virtual-reality simulations of the mission, wherein the model
is texture mapped with the original images. The system has been implemented, and the first tests on the ESA planetary terrain
testbed were successful. 相似文献
20.
Robust and efficient surface reconstruction from contours 总被引:1,自引:0,他引:1
We propose a new approach for surface recovery from planar sectional contours. The surface is reconstructed based on the so-called
“equal importance criterion,” which suggests that every point in the region contributes equally to the reconstruction process.
The problem is then formulated in terms of a partial differential equation, and the solution is efficiently calculated from
distance transformation. To make the algorithm valid for different application purposes, both the isosurface and the primitive
representations of the object surface are derived. The isosurface is constructed by means of a partial differential equation,
which can be solved iteratively. The traditional distance interpolating method, which was used by several researchers for
surface reconstruction, is an approximate solution of the equation. The primitive representations are approximated by Voronoi
diagram transformation of the surface space. Isosurfaces have the advantage that subsequent geometric analysis of the object
can be easily carried out while primitive representation is easy to visualize. The proposed technique allows for surface recovery
at any desired resolution, thus avoiding the inherent problems of correspondence, tiling, and branching. 相似文献