Superresoltuion Shader to Read Text in Virtual Reality
The Virtual Reality (VR) manufacture is in the midst of a new hardware bicycle – higher resolution headsets and better optics being the fundamental focus points for the device manufacturers. Similarly on the software front end, at that place has been a wave of content-rich applications and an emphasis on flawless VR experiences for the cease user.
With the introduction of the revolutionary Turing architecture, mainstream GPUs can now deliver the performance required for VR experiences at native resolutions.
In that location is an opportunity to tap the unused GPU cycles and harness that ability to deliver ameliorate image quality. Paradigm quality and minimal latency are notwithstanding the fundamental factors driving the immersive experience for VR users.
Variable Charge per unit Supersampling (VRSS) expands on Turing's Variable Rate Shading (VRS) feature to deliver image quality improvements by performing selective supersampling. This can besides be selectively engaged simply if idle GPU cycles are available. VRSS is completely handled from inside the NVIDIA display commuter without application programmer integration.
Background
Supersampling
MSAA (multi-sample antialiasing) is an antialiasing technique used to mitigate aliasing over the edges of geometries. This is facilitated by the usage of specialized multi-sampled buffers (render target). The bachelor configurations for the buffers are 2x, 4x, 8x (nX – where 'n' denotes the no. of samples allocated per-pixel). MSAA takes identify in the rasterization stage of the pipeline – the triangle is tested for coverage at each of the 'n' sample points, building a 16-scrap coverage mask identifying the portion of the pixel covered by the triangle. The pixel shader is then executed once and the values are shared beyond the samples identified by the coverage mask. This multi-sampled buffer is then resolved into a concluding frame buffer addressing edge aliasing.
SSAA (Supersampling antialiasing) operates on the higher up principle likewise, yet the difference beingness it executes the pixel shader for all the covered samples. This results in each sample location having its ain unique color value accurately computed. On resolving, this results in higher visual quality & higher performance cost compared to MSAA. MSAA operates along the geometric edges, whereas SSAA operates fifty-fifty inside the geometry.
Though SSAA seems to be advantageous for visual quality, it has its own limitations:
- SSAA is operation intensive – The pixel load scales linearly with the number of samples used
- No effectively command on shading rate – There is no mode to perform 2x supersampling on a 4x MSAA buffer nor can nosotros selectively shade objects based on the rendering region or any other criterion
Example of MSAA and SSAA
Figure 2 below shows each pixel as a foursquare and dots indicate sample locations within a pixel.
Before running Pixel Shaders, hardware generates a "coverage mask". This stores which samples are covered by the electric current triangle and which are not.
In Pixel1, all four samples are covered.
In Pixel2, only 3 samples are covered.
| MSAA | Supersampling |
| Pixel shader executes one time per pixel at the center, generates only one shade and replicates this to the "covered" samples | Pixel shader executes once per sample at sample locations, generates unique shades for each covered sample. |
| Pixel1: All four samples comprise the exact same shade, and so averaging them yields same shade: No Quality Comeback | Pixel1: All 4 samples incorporate unique shades, so averaging them yields more correct shade: Gives Quality Improvement + internal anti-aliasing |
| Pixel2: 3 samples incorporate the exact same shade, 4th sample contains background color, and then averaging them yields anti-aliased output: No Quality Improvement, but border anti-aliased | Pixel2: three samples contain unique shades, 4th sample contains background color, and then averaging them yields more correct and anti-aliased output: Gives Quality Improvement + edge anti-aliasing |
Super Resolution
Applications tin have an in-game dynamic scaling feature for scaling the rendering resolution. This arroyo involves scaling the render target by a gene. However such scaling is carried out across the entire frame. Even the unwanted periphery gets scaled & rendered at a higher resolution, which is not really required for VR. A better, but more complex solution would exist to scale the central region lonely for rendering and downsize it for meliorate quality.
Region of Interest
In VR the rendering regions could be categorized every bit foveated central region or the periphery region. Viewers tend to focus their attention generally at the central region of the screen for VR. Lens baloney significantly squashes the periphery of the image and isn't perceived past the user. Whatever enhancement carried out just on the cardinal region would improve the overall experience for the terminate users.
Turing Variable Charge per unit Shading (VRS)
Turing's VRS has the power to selectively control the shading rates across the rendering surface. Instead of executing the pixel shader one time per pixel, VRS tin can dynamically alter the shading rate during actual pixel shading in one of two means:
- Coarse Shading: Execution of the pixel shader once per multiple raster pixels and copying the same shade to those pixels
- Supersampling: Execution of the pixel shader more than in one case per single raster pixel
Such VRS capabilities allows the states to selectively ameliorate visual quality with supersampling applied just to the foveated key region.
Variable Charge per unit Supersampling (VRSS)
Introduction
VRSS operates on the principle of selectively supersampling the central region of a frame – fixed foveated supersampling. This is possible using Turing's VRS adequacy to apply dissimilar shading rates across a return target. While the fundamental region is supersampled, the peripheral region is untouched. VRSS can as well be selectively engaged merely if idle GPU cycles are bachelor.
The central region can be supersampled up to 8x – this is based on the MSAA level selected in the awarding. All this is completely handled from within the NVIDIA display driver without the need of any application integration.
VRSS
Users can enable VRSS from the NVIDIA Control panel -> 'Manage 3D Settings' folio -> 'Program Settings' tab. In that location are a couple of options to choose from while turning 'On' VRSS.
- Adaptive – Applies supersampling to the central region of a frame. Size of the central region varies based on the GPU headroom available
- Always On – Applies supersampling to the fixed size central region of a frame. This way does not consider the GPU headroom availability and might result in frame drops
This characteristic is available merely for applications which meet below criterion and are profiled by NVIDIA:
- DirectX 11 VR applications
- Forwards Rendered with MSAA
Nether the hood
VRSS does non require whatever programmer integration, and the entire characteristic is implemented and handled inside the NVIDIA display driver, provided the application is uniform and profiled past NVIDIA.
The NVIDIA display commuter handles several pieces of functionality internally, including:
- Frame Resources tracking – The commuter keeps track of the resource encountered per frame and builds a heuristical model to flag a scenario where VRS could be invoked. Notes the MSAA level to configure the VRS shading charge per unit – the supersampling factor to be used at the center of the image. Provides render target parameters for configuring the VRS Mask.
- Frame Render monitoring – This involves measuring the rendering load beyond frames, the current frame rate of the application, target frame rates based on the HMD refresh rate, etc. This in turn would be computing the rendering stats required for Adaptive fashion of VRSS.
- Variable Rate Supersampling enablement – As mentioned previously, VRS gives united states the ability to configure shading rate across the render surface. This is washed via a shading rate mask and shading charge per unit lookup table. The technical details for these are available here Turing Variable Charge per unit Shading in VRWorks. The VRS infrastructure setup – handles configuration of the VRS mask and the VRS shading charge per unit table lookup. The VRS framework is configured based on the performance stats equally followed:
- VRS Mask – Size of the cardinal region mask is configured proportionally to the headroom availability
- VRS Shading rates are configured based on the MSAA buffer's sample count detected
VRSS modes
Adaptive
The Adaptive manner takes performance limits into considerations – it tries to maximize the supersampling region and at the same time non hinder the VR feel. Here, the size of the primal region grows/shrinks in proportion to the GPU headroom available.
Always On
In this mode, a fixed foveated central region is always supersampled – providing maximum paradigm quality improvements. The size of the fundamental region is acceptable to cover the user's field of view at the center.
This manner will aid users to perceive the maximum IQ gains possible for a given title using VRSS. This however might result in frame drops for applications that are operation intensive.
Programmer Guidance
With VRSS, we accept provided a uncomplicated demonstration of the underlying VRS tech. This feature is bachelor for applications profiled by NVIDIA. Developers could submit their games and applications to NVIDIA for consideration.
The advantage of enlisting an application for VRSS would be as follows:
- No integration: No explicit VRS API integration is required. Completely encapsulated in NVIDIA Brandish commuter
- Ease of use : Simple switch (using NVIDIA control console) to plow on/off supersampling – enhanced epitome quality for the cease user
- Quality improvement: Supersampling provides the highest possible quality of rendering – also mitigates aliasing wherever possible
- Performance mode: Adaptive fashion tries to provide image quality comeback without suffering functioning losses
- Maintenance: Since the entire tech is at the commuter level, no maintenance is required from the developer side
Game and Application Compatibility
The criteria for profiling an awarding for VRSS is as follows:
- DirectX 11 VR applications
- Forward Rendered with MSAA – Supersampling needs MSAA buffer to be used hence applications using MSAA are compatible. The level of supersampling factor applied is based on the underlying no.of samples used in the MSAA buffer. The central region is shaded 2x for MSAA-2x, 4x supersampled for MSAA-4x & thereon. The maximum shading rate practical for supersampling is 8x. Higher the MSAA level, greater would be the supersampling effect.
Enabling MSAA in Unreal and Unity
MSAA is a pop anti-]aliasing technique associated with forward rendering, and it is well-suited to VR. Major game engines like Unreal and Unity take back up for forward rendering in VR. If the game is already forward rendered, adding MSAA support is relatively easy.
Content Suitability
Content that benefits from supersampling will benefit from VRSS likewise. Supersampling not only mitigates aliasing but also brings out details in an epitome. The degree of quality improvement will vary across content though
Supersampling shines when it encounters the following types of content:
- High resolution textures
- High frequency content
- Textures with alpha channels – fence, foliage, menu icons, text, etc.
Nevertheless information technology does not exhibit much IQ improvement for:
- Flat shaded geometry
- Texture with low level of detail
Come Onboard!
With VRSS, we have provided a simple demonstration of the underlying VRS engineering science for selective supersampling, and which does not need any application integration.
VRS technology is already available as explicit programming APIs, with fine grain control for application integration – VRWorks – Variable Charge per unit Shading (VRS). Developers can also leverage VRS on their own for lens matched shading, content adaptive shading, gaze tracked shading, etc.
VRSS (Variable Rate Supersampling) is directly available out of the box without requiring whatever awarding integration for DirectX eleven MSAA based applications profiled by NVIDIA. Come up onboard and submit your games and applications to NVIDIA for VRSS consideration.
The following 24 titles already support VRSS at launch with NVIDIA commuter 441.87
| Battlewake Boneworks Eternity WarriorsTM VR Hot Dogs, Horseshoes and Mitt Grenades In Decease Chore Simulator Killing Flooring: Incursion L.A. Noire: The VR Case Files Lonely Echo | Mercenary two: Silicon Rising Pavlov VR Raw Data Rec Room Rick and Morty: Virtual Rick-ality Robo Recall SairentoVR Serious Sam VR: The Last Promise Skeet: VR Target Shooting | Space Pirate Trainer Special Forcefulness VR: Infinity War Spiderman: Far from Dwelling house Spiderman: Homecoming – Virtual Reality Experience Talos Principle VR The Soulkeeper VR |
Source: https://developer.nvidia.com/blog/nvidia-vrss-a-zero-effort-way-to-improve-your-vr-image-quality/
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