The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform

Ruthie Harari-kremer - One of the best experts on this subject based on the ideXlab platform.

  • Studying long-term vegetation dynamics using Digital Processing of historical aerial photographs
    Remote Sensing of Environment, 1999
    Co-Authors: Ronen Kadmon, Ruthie Harari-kremer
    Abstract:

    Plant ecologists have long recognized the importance of aerial photographs as a data source for studies of vegetation dynamics. Recent advances in computer-aided technology (Digital photogrammetry, computerized image Processing, and geographical information systems) have opened new possibilities for the extraction of data on vegetation changes from aerial photographs. In this study we describe a computer-based approach for studying landscape-scale, long-term vegetation dynamics, using historical aerial photographs as a major data source. The method we employ consists of four main steps: 1) image scanning and preProcessing (rectification, georeferencing, spectral corrections and mosaicking), 2) image classification and construction of vegetation maps, 3) field validation, and 4) statistical analysis of vegetation changes. We applied our approach by analyzing changes in tree cover over a period of 32 years in a mountainous landscape dominated by Mediterranean maquis in northern Israel and discuss the main limitations and potential error sources of each stage of our analysis. We conclude that Digital Processing of historical aerial photographs may serve as a powerful tool for the detection, quantification, and analysis of landscape-scale patterns of vegetation dynamics. This conclusion is important because aerial photographs provide the largest source of information available today for research of long-term vegetation dynamics, and are the only source of information on vegetation dynamics that combines high spatial resolution, large spatial extent, and long-term coverage.

Yuyang Sun - One of the best experts on this subject based on the ideXlab platform.

  • Digital Processing technique for quasi-white light interference signal
    Advanced Sensor Systems and Applications, 2002
    Co-Authors: Fajie Duan, Yuyang Sun
    Abstract:

    A Digital Processing method for quasi-white light interference signal is proposed in the paper. A circuit based on EPP (Enhanced Parallel Port) is designed for high speed synchronous collecting. Envelope signals collecting is realized by means of interference fringe pulses synchronization, with the result that the space-domain interference envelope signals can be restored with high accuracy. A high accuracy algorithm for finding the acme of interference envelope signals, namely the point of zero optical path difference, is proposed in the paper. Compared with the traditional Processing method based on analog circuit, the new method overcomes the time-domain wave distortion of quasi-white light signal caused by the uneven moving velocity, therefore, the errors caused by the distortion are eliminated. The method is applied in the interference signal Processing of long coherent length. In the paper, the proposed method is emulated with computer and proved by experiments, and the results indicate that the locating accuracy of the points of zero optical path difference of fiber quasi-white interference signal is better than 0.5 interference fringes.

Petros Patias - One of the best experts on this subject based on the ideXlab platform.

  • 3D scanning and Digital Processing used in the study of a Neolithic figurine
    Applied Geomatics, 2011
    Co-Authors: Dimitrios Kaimaris, George Hourmouziadis, Petros Patias
    Abstract:

    At the lake settlement of Dispilio (sixth millennium B.C., W. Macedonia, Greece), two parts of a figurine were discovered with a difference of 10 years. The figurine’s importance, on an international level, due to its rare appearance, and its particularity that is due to the absence of the intermediary connective part imposed the metric documentation and the Digital correlation of the two figurine parts. Using a Micro Laser Scanner, the parts were scanned and, after the Digital Processing of the 3D point clouds, its initial shape was Digitally restored, triggering a new interdisciplinary discussion–study.

Sun Yu-yang - One of the best experts on this subject based on the ideXlab platform.

  • Digital Processing Method for Fiber Quasi-White Light Interference Signal
    Opto-electronic Engineering, 2003
    Co-Authors: Sun Yu-yang
    Abstract:

    A Digital Processing method for fiber quasi-white light interference signal is proposed. Envelope signal sampling is realized by interference fringe pulses synchronization, thus overcomes the influence caused by uneven guide moving velocity. The point with zero optical path difference is accurately determined by Gaussian function curve fitting and this greatly improves the positioning accuracy of quasi-white light interference signal. In order to eliminate the error caused by uncertainty of envelope signal sampling boundary point, some compensation is carried out with extrapolation method. The experiments show that the positioning accuracy of extrapolation method for zero optical path difference point of fiber quasi-white interference signal is less than 0.5 interference fringes.

Ronen Kadmon - One of the best experts on this subject based on the ideXlab platform.

  • Studying long-term vegetation dynamics using Digital Processing of historical aerial photographs
    Remote Sensing of Environment, 1999
    Co-Authors: Ronen Kadmon, Ruthie Harari-kremer
    Abstract:

    Plant ecologists have long recognized the importance of aerial photographs as a data source for studies of vegetation dynamics. Recent advances in computer-aided technology (Digital photogrammetry, computerized image Processing, and geographical information systems) have opened new possibilities for the extraction of data on vegetation changes from aerial photographs. In this study we describe a computer-based approach for studying landscape-scale, long-term vegetation dynamics, using historical aerial photographs as a major data source. The method we employ consists of four main steps: 1) image scanning and preProcessing (rectification, georeferencing, spectral corrections and mosaicking), 2) image classification and construction of vegetation maps, 3) field validation, and 4) statistical analysis of vegetation changes. We applied our approach by analyzing changes in tree cover over a period of 32 years in a mountainous landscape dominated by Mediterranean maquis in northern Israel and discuss the main limitations and potential error sources of each stage of our analysis. We conclude that Digital Processing of historical aerial photographs may serve as a powerful tool for the detection, quantification, and analysis of landscape-scale patterns of vegetation dynamics. This conclusion is important because aerial photographs provide the largest source of information available today for research of long-term vegetation dynamics, and are the only source of information on vegetation dynamics that combines high spatial resolution, large spatial extent, and long-term coverage.