首先分析了点数据符号化过程中的视觉变量相似性和绘制流程可重用性.在此基础上提出一种视觉变量相似性驱动的符号化过程模型.该模型将顺序型的地图符号化流程改变为符号化子过程可交叉共享的符号化流程.针对I/O密集的符号图形构造过程,提出图形缓存;针对计算密集的符号图形离散过程,提出扫描线缓存;针对像素操作密集的符号栅格化过程,提出栅格缓存.试验结果表明本文方法能够在保证绘制质量的前提下显著提高点数据的符号化效率.
The visual variable similarity and drawing process reusability was analyzed in the process of point data symbolization. Then, a symbolic process model driven by visual variable similarity was proposed. Compared with the sequential symbolization process, the subprocess of symbolization could be shared in this model. For I/O-intensive symbol graphical construction process, graphic cache was proposed. For compute-intensive symbol graphical discretization process, scan line cache was proposed. For pixel-operation-intensive symbol rasterization process, raster cache was proposed. Under the precondition that drawing quality is ensured, the experimental results show that the method presented can significantly improve the symbolic efficiency for point datasets.
[1] ROBINSON A C, PEZANOWSKI S, TROEDSON S. SymbolStore.org: A Web-based Platform for Sharing Map Symbols[J]. Cartography and Geographic Information Science, 2013, 40(5):415-426.
[2] PAUL A, MICHAEL G. Geographic Information Systems and Science[M]. New York: John Wiley and Sons Press, 2001.
[3] SWIENTY O, ZHANG M, REICHENBACHER T. Establishing a Neurocognition-based Taxonomy of Graphical Variables for Attention-guiding Geovisualisation[C]//Proceedings of SPIE. Nanjing: SPIE, 2007.
[4] NIVAN F, POCO J, VOHUY T. Visual Exploration of Big Spatio-temporal Urban Data: A Study of New York City Taxi Trips[J]. IEEE Transactions on Visualization and Computer Graphics, 2013, 19(12):2149-2158.
[5] ZHANG Chuanrong, LI Weidong. The Roles of Web Feature and Web Map Services in Real-time Geospatial Data Sharing for Time-critical Applications[J]. Cartography and Geographic Information Science, 2005, 32(4):269-297.
[6] MOLLER A T, STROM J. Graphics for the Masses: A Hardware Rasterization Architecture for Mobile Phones[J]. ACM Transaction of Graphics, 2003, 22(3):801-808.
[7] NOGUERA J M, SEGURA R J, OGAYAR C J. A Scalable Architecture for 3D Map Navigation on Mobile Devices[J]. Personal and Ubiquitous Computing, 2013,17(7):1487-1502.
[8] KILHYUNG C, DAEWOONG K, SOO-LK C. An Optimized Rendering Algorithm for Hardware Implementation of OpenVG 2D Vector Graphics[C]//Proceedings of SoC Design Conference. Busan:[s.n.],1995:338-341.
[9] DAEWOONG K, KILHYUNG C, SOO-LK C A High-performance OpenVG Accelerator with Dual-scanline Filling Rendering[J]. IEEE Transactions on Consume Electron, 2008,54(3):1303-1311.
[10] WU Xiaofang, DU Qingyun, XU Zhiyong. Design and Algorithm Optimization of Complex Linear Symbol[J]. Geomatics and Information Science of Wuhan University, 2006,31(7):623-635. (吴小芳, 杜清运, 徐智勇. 复杂线状符号的设计及优化算法研究[J]. 武汉大学学报:信息科学版,2006,31(7):623-635.)
[11] CAI Xianhua, WU Li. Study of Symbol Library Data Structure and Algorithm Based on Property Unit[J]. Acta Geodaetica et Cartographica Sinica, 2004,33(3):269-273. (蔡先华,武利.基于特征元的符号库数据结构及算法探讨[J].测绘学报, 2004, 33(3):269-273.)
[12] COMENETZ J. Cognitive Geometry for Cartography[J]. Cartographic Journal, 2002,39(1):65-77.
[13] BERTIN J. Semiology of Graphics: Diagrams, Networks, Maps[M]. Madison: University of Wisconsin Press,1983.
[14] CAO Yani, JIANG Nan, ZHANG Yajun, et al. Constitution Variables and Generation Modes of Electronic Map Symbols[J]. Acta Geodaetica et Cartographica Sinica, 2012,41(5):784-490. (曹亚妮,江南,张亚军,等.电子地图符号构成变量及其生成模式[J].测绘学报, 2012, 41(5):784-490.)
[15] MACEACHREN A M. How Maps Work: Representation, Visualization, and Design[M]. New York:The Guilford Press,1995.
[16] RICE D. OpenVG Specification Version 1.0.1[EB/OL].[2006-01-26]. http://www.khronos.org/files/openvg-quick-reference-card.pdf.
[17] GAMMA E, HELM R, JOHNSON R. Design Patterns: Elements of Reusable Object-oriented Software[M]. Boston: Addison-Wesley,1995.
[18] BLACK P E. Entry for Data Structure in Dictionary of Algorithms and Data Structures[EB/OL].[2009-05-21]. http://xlinux.nist.gov/dads/.
[19] Adobe Systems Inc. PostScript Language Reference Manual[M]. Boston: Addison-Wesley,1999.
[20] W3C Recommendation. Scalable Vector Graphics (SVG) Full 1.2 Specification[EB/OL].[2010-07-01]. http://www.w3.org/TR/SVG12.
