Research on DEM data coding

According to the characteristics of DEM data, each normal vector of vertex is calculated, quantified and coded based on multi-resolution wavelet-transform coding. Meanwhile, the data is displayed in three dimensions. This paper focuses on the DEM data coding based on wavelet transform, which enable the model to transmit and to display DEM data progressively. The calculation and coding method of vertex normal vector calculate the lighting effects, and produces the light and shadow effect. The method, proposed in the paper, includes Mipmap texture optimization techniques, and can produce desired effect. This method has a wide application prospect in the digital terrain elevation mapping and SOC chip lithography simulation and other fields.