Feature test checks variable shading rate


UL, formerly Futuremark, has announced a new feature test for the 3DMark: Starting August 26, 2019, owners of the Advanced and Professional Editions will be able to test how a variable shading rate affects image quality and frame rate. The technology is an optional component of Direct3D 12 and is currently only supported in hardware by Nvidia, specifically in the Turing chips of the Geforce RTX 2000. Intel will introduce Variable Rate Shading in 2019 with Ice Lake’s Gen11 graphics units for ultrabooks, AMD is expected to integrate it into next year’s RDNA v2 architecture.

The idea of Variable Rate Shading is to reduce the resolution of the shaders independently of the actual amount of pixels at certain locations in order to increase the frame rate without unduly reducing the image quality. Alternatively, developers can increase the shading rate to improve the optics for selected areas – a combination of both approaches is also possible, if desired. So far only Wolfenstein 2 The New Colossus supports a variable shading rate, but according to Microsoft the Unity and the Unreal Engine should be supported. In addition, developer studios such as 343 Industries, Activision, Stardock and Ubisoft have announced support.

For the new feature test UL uses a forest scene illuminated by lanterns at night: In the first run the variable Rate Shading is deactivated, in the second run it is switched on. Instead of shading a block of 16 pixels at the appropriate rate, only one operation is applied for highest performance. Here, 4×4 pixels are used for objects far away from the virtual camera, 2×2 for medium distance and 1×1 (i.e. pixel-accurate) for short distance. On screenshots the difference is clearly visible, in motion it depends more on the content. At Wolfenstein the variable rate shading partly causes artifacts such as floating pixels, but this may not occur with another implementation.


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Mette Frederiksen is a The Washington Newsday correspondent. With her coverage of general science, NASA and the interface between technology and society, Frederiksen has been in the Science Desk's Technology Beat since joining Washington Newsday in 2018.

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