Rendering fake soft shadows based on the erosion and dilation

Because of the low realism of the hard shadows and the slow speed of creation of the soft shadows, this article puts forward a fake soft shadows algorithm based on erode and dilate. First, we use shadow mapping algorithm to create the hard shadows, and then we use the boundary detection to find out the edge of the hard shadows, eroding the pixels inside the edge and dilating the pixels outside the edge. Last, we use the luminance map to render the whole scene. The results of the experiments indicate that this algorithm enhanced the realism of image, speeded up the shadow forming process, and with anti-aliasing. A good balance is achieved between the realism and real-time.