期刊名称：Archiwum Fotogrametrii, Kartografii i Teledetekcji
印刷版ISSN：2083-2214
出版年度：2006
卷号：16
语种：English
出版社：Main Board of Association of Polish Surveyors
摘要：Detection and automatic position measurement on digital images is one of the basic tasks of digital photogrammetry and is done using advanced photogrammetric software. In this paper,an attempt was made to show to what extent GIS software,which uses a raster data model,can be used to detect particular features of objects with close range digital images. Texture analysis can be useful in locating the position of balls attached to the human body in a photogrammetric system for 3D measuring for diagnosis of posture defects,developed in the Department of Photogrammetry and Remote Sensing Informatics of the University of Mining and Metallurgy,Kraków. The images of the patient are taken on a special measuring stand,simultaneously with the use of two digital cameras. The back of the patient body is also visible in the mirror situated behind the patient. The images were taken with a OLYMPUS CAMEDIA C120 digital camera with a resolution of 1600×1200 pixels. The images of balls are light or colored spots with an approximately circular shape and dimensions ranging from a few to a dozen or so pixels,depending on the local image scale. As criteria for ball detection,the similarity of spectral reflectance (in assumed range),dimension and shape similar to a circle were assumed. Promising results in detecting the balls have been achieved using the concept of fractal dimension.The image of fractal dimension were processed to eliminate features with fractal dimensions less then 2.8,remove feature areas less then 60 pixels and a compactness ratio greater then 0.72. The parameters were chosen by closely analyzing typical images and then applying these parameters to analyze the other two. The selected procedure properly detected 85 % of the signal points. In determining the value of parameters,it was assumed that there would be fewer mistakes if more features were detected than for using excessively sharp criteria and omitting some features. For the position of detected objects,the coordinates of the center of gravity of the feature determined by polyras (option polygon locator) were assumed. To estimate the accuracy of the coordinate determined automatically,a manual comparison was done. The standard deviation of the coordinates’ differences equalled Sx,y = ±0.32 pixel size,which corresponded to 1÷2 mm in the object scale. The achieved accuracy is sufficient for diagnosis of posture defects. In the analysis,a IDRISI32 was used.
其他摘要：Wykrywanie i automatyczny pomiar połoŜenia punktów na obrazach cyfrowych jest jednym z podstawowych zadań fotogrametrii cyfrowej i realizowane jest przez zaawansowane oprogramowanie fotogrametryczne. W artykule podjęto próbę oceny na ile oprogramowanie GI
