KEYWORDS: Data modeling, Image segmentation, 3D modeling, Feature extraction, Image fusion, Visual process modeling, Geometrical optics, Data acquisition, Principal component analysis, Photogrammetry
The building facade model is one of main landscapes of a city and basic data of city geographic information. It is widely useful in accurate path planning, real navigation through the urban environment, location-based application, etc. In this paper, a method of facade model refinement by fusing terrestrial laser data and image is presented. It uses the matching of model edge and image line combined with laser data verification and effectively refines facade geometry model that reconstructed from laser data. The laser data of geometric structures on building facade such as window, balcony and door are segmented, and used as a constraint for further selecting the optical model edges that are located at the cross-line of point data and no data. The results demonstrate the deviation of model edges caused by laser sampling interval can be removed in the proposed method.
Icing thickness parameter is the basic data for power sector to make decision for icing accident prevention. In this paper, a transmission line icing measurement method is proposed. It used the photogrammetry method to realize icing parameters measurement through the integration of high resolution camera, laser range finder and inertial measurement unit. Compared with traditional icing measurement method, this method is flexible and is the effective supplement of the fixed icing detection terminal. And its high accuracy measurement guarantees the reliability of the icing thickness parameters.
This paper mainly proposes a change detection method for different time remote sensing image by combining mean
pixel ratio and post-classification comparison. Mean pixel ratio method can get more continuous result comparing with
traditional pixel ratio, but the threshold needed is still determined by training sample. The distribution and numbers of
sample can have an effect on the value of threshold and further lead to different results of change detection. To solve this
problem, we propose an automatic, adaptive threshold determination method that the entire image is evenly sampled, and
the appropriate threshold is determined by the histogram method without human intervention. For post-classification
comparison, we use supervised classification module in Erdas software to classify two different time images and
compare the difference. Our method weights the results of adaptive mean pixel ratio and post-classification comparison.
Experiments show that the adaptive threshold determination can ensure the objectivity of threshold and improve the
efficiency of change detection and the fusion of the result of two methods can improve the reliability of change
detection.
It is an important work to measure insulator geometric parameters for preventing pollution flashover on power
transmission lines. This paper presents an effective method to measure insulator parameters based on non-touch
photogrammetric method. In this paper, the insulator reconstruction takes full advantage of the rotating body's geometry
structure about the symmetry axis. The spindle of insulator can be calculated from its profile extracted from multiple
insulator images acquired by calibrated cameras and radius is obtained by the homologous image points of insulator
profiles. Results from real data are presented, demonstrating the efficiency of the proposed methods.
The technology of quickly generating city image mosaic is widely applied in urban planning, evaluating natural disasters
and meeting city's emergency service. This paper utilizes existing 1:2000 orthophoto and 1:500 digital line graph (DLG)
to get control information, and calculate parameters of image mosaic by image matching and aerotriangulation. At last
quick and seamless auto-mosaic is implemented based on Thiessen polygon. Test results prove that our approach can
quickly obtain large mosaic images, which satisfies the need of many society applications.
In this paper, we describe an effective method for fast checking the quality of digital orthoimages. In order to ensure the
accuracy and precision of digital orthoimages (DOM) before putting into database, we consider metadata, coordinate
data, geometry accuracy, and histogram quality of images as evaluating rules. Template matching is used in Metadata
inspection. Coordinate data inspection is based on the relation between the standard file name of maps and coordinates of
maps. Image matching technique is performed in geometry accuracy inspection. Image histogram quality is evaluated by
the normal distributing curve characteristic. The method is tested feasible in applications for checking the quality of
digital orthoimages.
In this paper, a automatic approach of geometry precision checking for digital ortho-image (DOM), especially for a batch of DOM, is proposed. Automatic image matching between DOM with various resolution was performed in the DOM checking based on reference DOM with higher resolution. Automatic extraction of linear feature was used in the DOM checking based on reference vector map with higher precision. A lot of experiments testify that the method of this paper
can improve the efficency and reliability of checking method of DOM image for geometry precision.
The paper presents an algorithm to find homonymous line segments from images based on the depth face of building. TIN is formed from the object points calculated by homonymous points in stereopair, and contour lines are inserted from TIN with a given interval. With image and contour lines, the different depth faces of building can be partitioned approximately. Homonymous line segments are found in different depth faces by matching along epipolar line, the method is tested feasible. It solves the problem of line matching in the changed area of building depth face simultaneously.
The solution of camera's orientation parameters is one of the most important tasks in photogrammetry. The approach presented in this paper is based on the coplanar relationship, three-axes orthogonal constraints and parallel line information. The interior orientation parameters and rotation matrix are solved with parallel information and least-square adjustment. The test of the prosed method is based on the real data.
Currently, much work has been done in the area of image storage and retrieval. However, the overall performance has been far from practical. A highly integrated wavelet-based image management system is proposed in this paper. By integrating wavelet-based solutions for image compression and decompression, content-based retrieval and progressive transmission, much higher performance can be achieved. The multiresolution nature of the wavelet transform has been proven to be a powerful tool to represent images. The wavelet transform decomposes the image into a set of subimages with different resolutions. From here three solutions for key aspects of image management are reached. The content-based image retrieval (CBIR) features of our system include the color, contour, texture, sample, keyword and topic information of images. The first four features can be naturally extracted from the wavelet transform coefficients. By scoring the similarity of users' requests with images in the database, those who have higher scores are noted and the user receives feedback. Image compression and decompression. Assuming that details at high resolution and diagonal directions are less visible to the human eye, a good compression ratio can be achieved. In each subimage, the wavelet coefficients are vector quantized (VQ), using the LGB algorithm, which is improved in our approach to accelerate the process. Higher compression ratio can be achieved with DPCM and entropy coding method applied together. With YIQ representation, color images can also be effectively compressed. There is a very low load on the network bandwidth by transmitting compressed image data across the network. Progressive transmission is possible by employment of the multiresolution nature of the wavelet, which makes the system respond faster and the user-interface more friendly. The system shows a high overall performance by exploring the excellent features of wavelet, and integrating key aspects of image management. An image retrieval service using Java is also available on the world wide web (www), to demonstrate the system's features.
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