nvidia pcss refers to the shading technology of the graphics card chip, which determines the clarity based on the projection distance. The core principle of PCSS soft shadow is to adaptively adjust the filter kernel size of PCF according to the distance between the light source S and the shading point and the occlusion object; the filter kernel size at the edge of the shadow is determined by the penumbra distance, and the penumbra distance is determined by the size of the light source, the distance between the light source and the occlusion object. Determined by the distance of the occlusion object and the distance between the shading plane and the occlusion object.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
nvidia pcss refers to the shading technology of the graphics card chip, which determines the clarity based on the projection distance.
Soft shadow generation technology PCSS (Percentage Closer Soft Shadows)
PCSS (Percentage Closer Soft Shadows) soft shadow method, can Automatically adjust the filter kernel size according to the light source and the distance from the shading point to the occlusion object to obtain a more realistic soft shadow effect. The larger the light source, the softer the shadow edge transition; the further away the shading point is from the occlusion object, the softer the shadow edge transition.
The core principle of PCSS soft shadow is to adaptively adjust the filter kernel size of PCF according to the distance between the light source and the shading point and the occlusion object. The filter kernel size of the shadow edge is determined by the penumbra distance, as shown in the figure below. According to the principle of similar triangles, the penumbra distance is determined by the size of the light source, the distance between the light source and the occlusion, and the distance between the shading plane and the occlusion. The larger the penumbra distance is, the larger the sampling range used for PCF filtering, the softer the shadow edge, and the noise will increase accordingly. The specific algorithm steps are as follows:
Calculate the average distance from the obstruction to the Camera.
According to the size of the light source, the average distance of the occlusion object and the distance from the light to the coloring point, use the similar triangle theorem to find the penumbra distance.
In the penumbra distance, use a Poisson disk for random sampling, and compare the camera space depth with the Shadow Map depth to determine whether it belongs to the shadow area. The average of multiple samples is calculated to calculate the final result. The shadow pixel visibility determines the shadow brightness.
PCSS does not generate soft shadows based on the area light source. The light source is still a point light source, but only simulates the soft shadow of the area light source
Extended knowledge:
The display chip is the core chip of the graphics card, and its performance directly determines In addition to the performance of the graphics card, its main task is to process the video information input by the system and construct and render it.
The performance of the main display chip directly determines the performance of the display card. Different display chips have differences in terms of internal structure and performance, and their prices also vary greatly. The status of the display chip in the graphics card is equivalent to the status of the CPU in the computer, and is the core of the entire graphics card. Due to the complexity of display chips, currently the only manufacturers that design and manufacture display chips are NVIDIA, ATI, SIS, VIA and other companies. Home entertainment graphics cards all use single-chip design display chips, while some professional workstation graphics cards use a combination of multiple display chips.
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