In order to provide synchronous map service based on message semantics in instant communication software, this paper proposes a technical solution, basically a comprehensive combination of Chinese text segmentation, pattern recognition, and image-text integrated service. A case study based on actual WeChat communication messages is carried out to verify the technical solution, which shows that the proposed solution is both feasible and practically effective. The synchronous message semantics-based image-text integrated service provided by the case study improves the user experience very well.

By taking Tianjin urban area as an example, a method is proposed to extract urban expansion by combining multi-temporal Landsat TM/ETM+ images and DMSP/OLS nighttime light data, and validated and analyzed. First, the candidate built-up area extent were obtained from DMSP/OLS data. Multitemporal Landsat TM/ETM+ images and derived multivariate textures of the obtained urban extent were classified to extract built-up areas for different dates. Urban expansions for different time intervals were obtained by post-classification comparison method. In addition, the thresholding method was applied to multitemporal DMSP/OLS nighttime light data to extract urban extents for different years and urban expansions of different time intervals were produced. The urban expansion results from DMSP/OLS data and urban statistical data were used to verify the Landsat TM/ETM+ results. The results demonstrate that the combination of Landsat data and DMSP/OLS data effectively reduce the spectral confusion between bare land and urban area and thus produce higher accuracy than useing spectral data from Landsat TM/TM+ images alone in extraction of urban built-up area expansion. Combination of Landsat TM/ETM+ data and DMSP/OLS nighttime light data provides an effective method for urban expansion extraction in mega-city areas.