一种逐步简化的扫描工程图纸矢量化方法-CUHKCSE.pptVIP

Introduction to Vectorization of Engineering Drawings Song Jiqiang 18/9/2001 Concept Vectorization: the conversion from a raster image to its vector-form file. Why do vectorization? A lot of old drawings to be reused, and CAD files are more editable than images. Preprocess of automatic drawing understanding systems (information statistic, 3D reconstruction). Save the storage space. History Begin research on vectorization at late 70’s; Begin that for engineering drawings at late 80’s; Related organizations publications IAPR TC-10, IEEE IEEE T.PAMI, PR, PRL, CVIU, CVGIP, etc. ICPR, ICDAR, IEEE CVPR, etc. State of arts K. Tombre (LNCS vol.1389, 1998) : “None of these methods works. … Actually, the methods do work, but none of them is perfect.” 《CADALYST》performs the annual evaluation on commercial vectorization systems. Review of existing methods Thinning based CT(Contour Tracking) based RLE(Run Length Encoding) based SPT(Sparse Pixel Tracking) based Thinning-based methods CT-based methods RLE-based methods SPT-based methods Existing difficulties Lines with intersections ? broken into pieces. Texts touch lines ? misrecognition. The interference of recognized objects ? repetitive detection, false detection. Our research Analysis the vectorization model of existing methods. Propose an efficient vectorization model for engineering drawings. Propose a group of new graphical object recognition algorithms. Common model of existing methods（2PV - 2 Phase Vectorization） Motivation of 2PV Internal memory (RAM) Used to be high price limit capacity High pixel access frequency cause swap Pixel tracking algorithm No guide direction Repetitive tracking Object-Oriented Progressive-Simplification based Vectorization Model 1 phase model Imitate the way that humans read drawings Recognize a graphical object in its entirety Object-oriented feature Simplify the image data as the recognition goes on Progressive-simplification feature Workflow of OOPSV Graphical object recognitio