Intervisibility analysis method based on DEM raster data

The invention discloses an intervisibility analysis method based on DEM raster data. The intervisibility condition of the observation point between any points within the maximum intervisibility distance is analyzed in real time by using the summary height data; the method comprises the following steps: firstly, calculating the minimum height required by the visibility between the position where DEM grid pixels are located and an observation point offline; obtaining minimum visual height raster data, dividing the minimum visual height raster data into a plurality of pieces of block data, performing statistics on summary information of each piece of block data to obtain summary height data, the summary information of the block data comprising a maximum pixel value in a block and a minimum pixel value in the block; then performing intervisibility analysis based on summary information of the block data; therefore, only summary height data with very small data volume need to be called intothe memory during intervisibility analysis, so that original data required by real-time calculation is greatly reduced, multiple file IO operations are avoided, the intervisibility analysis efficiencyis remarkably improved, and meanwhile, the calculation accuracy is also ensured. The invention further discloses another intervisibility analysis method.