Study On The Vectorization Technology Of Dot Matrix Meteorological Facsimile Maps

Nowadays, some kinds of facsimile maps of weather and sea condition can be received easily by meteorological facsimile receivers, which have been popular in watercrafts. Meteorological facsimile maps are numerical forecasting products in the way of images, therefor navigation personnel can read them directly, however, the ability of unscrambling is according to the weather knowledge owned by himself.It restricts the depth and extent of application of weather information in navigation activities.It can turn dot matrix data format of meteorological facsimile maps to vector data format, by vectorizing them, not only adding weather information to electronic charts, therefore, we can forcast the weather and sea condition on planning lines, but also providing foundation for digitizing of meteorological facsimile maps, which is the foundation of transforming qualitative analysis of maps to quantitative analysis.This paper begins with basic theories and methods of image vectorization technology.On the basis of analying and summarizing of vectorization algorithms, I put forward my idea about vectorizing meteorological facsimile maps, according to the characters of meteorological facsimile maps.This paper provides some methods of pretreatment, on the basis of different characters of elements in structure and location .Therefor, every element can be picked up or removed, turning a big map to some small maps with single element and predigesting the process of vectorization.It is discussed in detail on the vectorization of isotherm of COPQ1 meteorological facsimile map. This paper adopts a method to seperate the thick contours and thin contours by constringency transform,decreasing interference between lines and the improving the precision of vectorization.In the process of vectorizing thick contours and thin contours separately,we adopt algorithms ,such as thinning,line tracing,dealing with conglutination,connecting contour and compressing vector,realizing vectorization of map and compressing datas.At last, this paper puts the result of vectorization of isotherm into primary use, realizing interpolation and calculation of the temperature of an objective point. Therefore, it can settle foundation for practical project application.