共查询到20条相似文献,搜索用时 12 毫秒
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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
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The maxima of Curvature Scale Space (CSS) image have been used to represent 2D shapes under affine transforms. The CSS image
is expected to be in the MPEG-7 package of standards. Since the CSS image employs the arc length parametrisation which is
not affine invariant, we expect some deviations in the maxima of the CSS image under general affine transforms. Affine length
and affine curvature have already been introduced and used as alternatives to arc length and conventional curvature in affine
transformed environments. The utility of using these parameters to enrich the CSS representation is addressed in this paper.
We use arc length to parametrise the curve prior to computing its CSS image. The parametrisation has been proven to be invariant
under affine transformation and has been used in many affine invariant shape recognition methods. Since the organisation of
the CSS image is based on curvature zero crossings of the curve, in this paper, we also investigate the advantages and shortcomings
of using affine curvature in computation of the CSS image. The enriched CSS representations are then used to find similar
shapes from a very large prototype database, and also a small classified database, both consisting of original as well as
affine transformed shapes. An improvement is observed over the conventional CSS image. 相似文献
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Stefan Berchtold Daniel A. Keim Hans-Peter Kriegel 《The VLDB Journal The International Journal on Very Large Data Bases》1997,6(4):333-348
In this paper, we introduce the concept of extended feature objects for similarity retrieval. Conventional approaches for
similarity search in databases map each object in the database to a point in some high-dimensional feature space and define
similarity as some distance measure in this space. For many similarity search problems, this feature-based approach is not
sufficient. When retrieving partially similar polygons, for example, the search cannot be restricted to edge sequences, since
similar polygon sections may start and end anywhere on the edges of the polygons. In general, inherently continuous problems
such as the partial similarity search cannot be solved by using point objects in feature space. In our solution, we therefore
introduce extended feature objects consisting of an infinite set of feature points. For an efficient storage and retrieval
of the extended feature objects, we determine the minimal bounding boxes of the feature objects in multidimensional space
and store these boxes using a spatial access structure. In our concrete polygon problem, sets of polygon sections are mapped
to 2D feature objects in high-dimensional space which are then approximated by minimal bounding boxes and stored in an R-tree. The selectivity of the index is improved by using an adaptive decomposition of very large feature objects and a dynamic
joining of small feature objects. For the polygon problem, translation, rotation, and scaling invariance is achieved by using
the Fourier-transformed curvature of the normalized polygon sections. In contrast to vertex-based algorithms, our algorithm
guarantees that no false dismissals may occur and additionally provides fast search times for realistic database sizes. We
evaluate our method using real polygon data of a supplier for the car manufacturing industry.
Edited by R. Güting. Received October 7, 1996 / Accepted March 28, 1997 相似文献
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Approximate similarity retrieval with M-trees 总被引:4,自引:0,他引:4
Pavel Zezula Pasquale Savino Giuseppe Amato Fausto Rabitti 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(4):275-293
Motivated by the urgent need to improve the efficiency of similarity queries, approximate similarity retrieval is investigated
in the environment of a metric tree index called the M-tree. Three different approximation techniques are proposed, which
show how to forsake query precision for improved performance. Measures are defined that can quantify the improvements in performance
efficiency and the quality of approximations. The proposed approximation techniques are then tested on various synthetic and
real-life files. The evidence obtained from the experiments confirms our hypothesis that a high-quality approximated similarity
search can be performed at a much lower cost than that needed to obtain the exact results. The proposed approximation techniques
are scalable and appear to be independent of the metric used. Extensions of these techniques to the environments of other
similarity search indexes are also discussed.
Received July 7, 1998 / Accepted October 13, 1998 相似文献
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Shape similarity by homotopic deformation 总被引:1,自引:0,他引:1
nk +n log n) time, where n is the number of vertices in the polygonal shapes and k is an index to indicate how the target shape is convoluted. Experimental results show the feasibility of our approach.
Extending the method for comparison of scenes with mutiple objects is also discussed. 相似文献
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For more than a decade, researchers have actively explored the area of image/video analysis and retrieval. Yet one fundamental
problem remains largely unsolved: how to measure perceptual similarity between two objects. For this purpose, most researchers
employ a Minkowski-type metric. Unfortunately, the Minkowski metric does not reliably find similarities in objects that are
obviously alike. Through mining a large set of visual data, our team has discovered a perceptual distance function. We call
the discovered function the dynamic partial function (DPF). When we empirically compare DPF to Minkowski-type distance functions in image retrieval and in video shot-transition
detection using our image features, DPF performs significantly better. The effectiveness of DPF can be explained by similarity theories in cognitive psychology. 相似文献
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We propose a new image registration scheme for remote sensing images. This scheme includes three steps in sequence. First,
a segmentation process is performed on the input image pair. Then the boundaries of the segmented regions in two images are
extracted and matched. These matched regions are called confidence regions. Finally, a non-linear optimization is performed
in the matched regions only to obtain a global set of transform parameters. Experiments show that this scheme is more robust
and converges faster than registration of the original image pair. We also develop a new curve-matching algorithm based on
curvature scale space to facilitate the second step. 相似文献
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The development of a system supporting querying of image databases by color content tackles a major design choice about properties
of colors which are referenced within user queries. On the one hand, low-level properties directly reflect numerical features
and concepts tied to the machine representation of color information. On the other hand, high-level properties address concepts
such as the perceptual quality of colors and the sensations that they convey. Color-induced sensations include warmth, accordance or contrast, harmony, excitement, depression, anguish, etc. In other words, they refer to the semantics of color usage. In particular, paintings are an example where the message is contained more in the high-level color qualities
and spatial arrangements than in the physical properties of colors. Starting from this observation, Johannes Itten introduced
a formalism to analyze the use of color in art and the effects that this induces on the user's psyche. In this paper, we present
a system which translates the Itten theory into a formal language that expresses the semantics associated with the combination
of chromatic properties of color images. The system exploits a competitive learning technique to segment images into regions
with homogeneous colors. Fuzzy sets are used to represent low-level region properties such as hue, saturation, luminance,
warmth, size and position. A formal language and a set of model-checking rules are implemented to define semantic clauses
and verify the degree of truth by which they hold over an image. 相似文献
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Fast image retrieval using color-spatial information 总被引:1,自引:0,他引:1
Beng Chin Ooi Kian-Lee Tan Tat Seng Chua Wynne Hsu 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(2):115-128
In this paper, we present an image retrieval system that employs both the color and spatial information of images to facilitate
the retrieval process. The basic unit used in our technique is a single-colored cluster, which bounds a homogeneous region of that color in an image. Two clusters from two images are similar if they are of the
same color and overlap in the image space. The number of clusters that can be extracted from an image can be very large, and
it affects the accuracy of retrieval. We study the effect of the number of clusters on retrieval effectiveness to determine
an appropriate value for “optimal' performance. To facilitate efficient retrieval, we also propose a multi-tier indexing
mechanism called the Sequenced Multi-Attribute Tree (SMAT). We implemented a two-tier SMAT, where the first layer is used to prune away clusters that are of different colors,
while the second layer discriminates clusters of different spatial locality. We conducted an experimental study on an image
database consisting of 12,000 images. Our results show the effectiveness of the proposed color-spatial approach, and the efficiency
of the proposed indexing mechanism.
Received August 1, 1997 / Accepted December 9, 1997 相似文献
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Relevance feedback in image retrieval: A comprehensive review 总被引:23,自引:1,他引:22
We analyze the nature of the relevance feedback problem in a continuous representation space in the context of content-based
image retrieval. Emphasis is put on exploring the uniqueness of the problem and comparing the assumptions, implementations,
and merits of various solutions in the literature. An attempt is made to compile a list of critical issues to consider when
designing a relevance feedback algorithm. With a comprehensive review as the main portion, this paper also offers some novel
solutions and perspectives throughout the discussion.
RID="*"
ID="*" Work was done while at the University of Illinois. 相似文献
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Accuracy and efficiency are the two important issues in designing content-based image retrieval systems. In this paper, we present an efficient image retrieval system with high performance of accuracy based on two novel features, the composite sub-band gradient vector and the energy distribution pattern string. Both features are generated from the sub-images of a wavelet decomposition of the original image. A fuzzy matching mechanism based on energy distribution pattern strings serves as a filter to quickly remove undesired images in the database from further consideration. The images passing the filter will be compared with the query image based on composite sub-band gradient vectors which are extremely powerful for discriminating detailed textures. Through several extensive experiments by exercising our prototype system with a database of 2400 images, we demonstrated that both high accuracy and high efficiency can be achieved at the same time by our approach. 相似文献
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《Graphical Models》2014,76(2):57-69
This paper presents a novel approach based on the shape space concept to classify deformations of 3D models. A new quasi-conformal metric is introduced which measures the curvature changes at each vertex of each pose during the deformation. The shapes with similar deformation patterns follow a similar deformation curve in shape space. Energy functional of the deformation curve is minimized to calculate the geodesic curve connecting two shapes on the shape space manifold. The geodesic distance illustrates the similarity between two shapes, which is used to compute the similarity between the deformations. We applied our method to classify the left ventricle deformations of myopathic and control subjects, and the sensitivity and specificity of our method were 88.8% and 85.7%, which are higher than other methods based on the left ventricle cavity, which shows our method can quantify the similarity and disparity of the left ventricle motion well. 相似文献
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NeTra: A toolbox for navigating large image databases 总被引:17,自引:0,他引:17
We present here an implementation of NeTra, a prototype image retrieval system that uses color, texture, shape and spatial
location information in segmented image regions to search and retrieve similar regions from the database. A distinguishing
aspect of this system is its incorporation of a robust automated image segmentation algorithm that allows object- or region-based
search. Image segmentation significantly improves the quality of image retrieval when images contain multiple complex objects.
Images are segmented into homogeneous regions at the time of ingest into the database, and image attributes that represent
each of these regions are computed. In addition to image segmentation, other important components of the system include an
efficient color representation, and indexing of color, texture, and shape features for fast search and retrieval. This representation
allows the user to compose interesting queries such as “retrieve all images that contain regions that have the color of object
A, texture of object B, shape of object C, and lie in the upper of the image”, where the individual objects could be regions
belonging to different images. A Java-based web implementation of NeTra is available at http://vivaldi.ece.ucsb.edu/Netra. 相似文献
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I. Laptev H. Mayer T. Lindeberg W. Eckstein C. Steger A. Baumgartner 《Machine Vision and Applications》2000,12(1):23-31
Abstract. We propose a new approach for automatic road extraction from aerial imagery with a model and a strategy mainly based on the
multi-scale detection of roads in combination with geometry-constrained edge extraction using snakes. A main advantage of
our approach is, that it allows for the first time a bridging of shadows and partially occluded areas using the heavily disturbed
evidence in the image. Additionally, it has only few parameters to be adjusted. The road network is constructed after extracting
crossings with varying shape and topology. We show the feasibility of the approach not only by presenting reasonable results
but also by evaluating them quantitatively based on ground truth.
Received: 22 July 1999 / Accepted: 20 March 2000 相似文献