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How Intel Optimized the User Experience for VR e-Sports

Introduction

Code51 is the primary worldwide mech area VR recreation supporting Oculus Rift, HTC Vive, PSVR and Pico VR. It permits as much as 4 versus 4 fight amongst worldwide gamers and is particularly tailor-made for VR e-sports, with a nausea minimized gameplay design and a built-in VR spectator mode. Code51 has already been launched in over 3000 VR Arcades and expertise facilities in China (ZamerVR & VRLe), and is focused to be launched on PlayStation Retailer, Oculus Retailer and Steam in Q2’18.

Intel labored carefully with Smellyriver to optimize the person expertise and efficiency of the sport. Furthermore Intel and Smellyriver added richer visible and audial enhancements enabled by Intel Core i7 processors, together with options like 3D audio, object destruction, enhanced CPU particles and extra background objects.

On this article, we’ll describe seven design factors in Code51 that may assist enhance each the immersion and person expertise of VR video games.

Design Factors of Immersive VR Video games

Transferring immersively in VR

At present there are 4 lessons of immersive movement monitoring methods to drive participant actions within the digital world of a recreation, that are:

  • Teleport + Six DoF Monitoring (e.g. Rebo Recall)
  • Digital Cockpit (e.g. EVE: Valkyrie)
  • Locomotion Simulator (e.g. Virtuix Omni)
  • Massive Scale Monitoring System (e.g. OptiTrack)

All of those options have totally different professionals and cons. For Code51, digital cockpit was chosen to be the way in which to maneuver in VR as a result of following causes:

  1. In a position to transfer constantly is a vital approach to enhance immersion in VR because it matches our real-world expertise, and digital cockpit is the one approach that may transfer constantly in VR with out the necessity of additional {hardware} and price.
  2. Contemplating that present gross sales of Premium VR helmets will not be excessive sufficient, a transferring approach which is suitable to 3DoF VR helmets helps scale back the engineering effort of porting the sport to those gadgets.
  3. Code51 is an area VR recreation the place a participant sits within the cockpit of a mech and fights with others in VR. This sort of “sitting down” expertise completely matches the transferring approach of digital cockpit and will increase the immersion.
  4. Sitting & utilizing gamepad to play is much less tiring than standing & utilizing movement controllers to play, it permits customers to play longer in VR[1]. Fig. 1 exhibits how the customers play Code51 with varied VR helmets.

Fig. 1. Code51 helps varied VR helmets. Left: HTC Vive (6 DoF). Proper: Pico VR (Three DoF).

Assuaging movement illness in VR

Movement illness[2] is without doubt one of the predominant elements stopping customers from experiencing VR for a comparatively lengthy time period. There are a number of elements inflicting it, together with:

  • Visible stress attributable to the vergence-accommodation battle of the viewers[3]
  • VR scene w/o directional clues or references (i.e. not capable of get hints on the present transferring route)
  • Low FPS or excessive MTP latency
  • Acceleration mismatch between what you see and what your physique feels
  • Angular velocity
  • Zoom in & zoom out
  • VR blur

To deal with the elements resulting in dizziness, a number of approaches have been adopted in Code51 to attenuate these results from varied elements

  • UI Design
    • Put the rendered management panel at 1 meter or extra away from the person to keep away from frequent altering of the person’s vergence distance
  • Stage Design
    • Present clear directional cues within the scene such that the person is aware of which route he/she goes persistently. It could get one’s mind ready for the motion and scale back dizziness. In apply, keep away from including objects with plain texture which may block the entire view of the person to the scene, for it would interrupt the feeling of the transferring route from visible clues, rising the equal variation of perceived pace.
  • Rendering Efficiency
    • Optimize efficiency to get Code51 stably rendered at 90fps for minimizing MTP latency.
  • Cut back Acceleration
    • Keep away from including acceleration to Code51 as a lot as attainable to cut back dizziness, velocity ought to be modified between totally different ranges immediately. For instance, apply acceleration for a brief time period solely to initialize the motion, after which preserve fixed pace throughout leaping or touchdown.
  • Cut back Angular Velocity
    • Cut back the power to rotate (angular velocity) at excessive pace, cockpit acts as a reference and helps scale back perceived optical movement.
  • Dynamically scale back the sphere of view (FOV)
    • Proscribing the FOV in VR helps scale back movement illness[4][5]. This methodology was adopted in Code51 the place depth buffer is used to calculate the moment velocities at Four corners of the display screen, after which the vertices are warped inward accordingly within the stencil buffer to subtly scale back the FOV throughout motion. The quicker the transferring, the narrower the FOV, as proven in Fig. 2. It could scale back the equal magnitude of optical movement perceived by finish customers. 

Fig. 2. Dynamic FOV adopted in Code51 to remove the optical flows on the edges of the display screen. It helps scale back the movement illness induced to the top customers.

Minimizing community latency

For VR utility, it’s additionally necessary to attenuate community latency to be able to have a fluent gameplay expertise with out lagging, for it would generate dizziness if not optimized. In Code51, all movement of mechs are predicted regionally, after which being refined by means of synchronization with the server in a low frequency tempo to keep away from frequent interruption throughout dangerous community situation. If synchronization was failed, the shopper would extrapolate earlier trajectory to get the brand new place.

Enhancing spectator viewing expertise for e-Sports activities

To create a greater viewing expertise for e-Sports activities viewers, a built-in VR spectator mode was applied in Code51. The spectator mode acts like a shopper within the recreation and permits viewers to observe a stay battle in both stereo or mono mode.  Spectators can use VR HMDs or not, and consider from any angles and positions they need by means of keyboard, mouse or gamepad management, as proven in Fig. 3.

Fig. 3. VR spectator mode in Code51. Finish customers can view a stay battle in VR or non-VR mode.

Keep the sharpness of the rendered scene

For the reason that PPD (Pixels Per Diploma) of present VR HMDs continues to be low as in comparison with standard shows, it’s essential for VR apps to protect the sharpness of the rendered scene as a lot as attainable to attenuate VR blur and scale back dizziness. At present there are Three forms of Anti-Aliasing (AA) approaches accessible to the UE4 builders:

  • Temporal AA (TAA)
    • TAA and its derivatives have good AA high quality for static atmosphere with average computational price. If TAA is utilized in VR apps, it must be computed in further move for non-opaque objects since there is no such thing as a depth info accessible for these objects. Additionally, it’s higher to undertake a conservative parameter settings for TAA utilized in VR to be able to scale back VR blur generated throughout head motion or in dynamic scenes.
  • Multi-Pattern AA (MSAA)
    • MSAA is on the market in ahead rendering pipeline solely, it’s adopted in Code51 to attenuate VR blur generated from AA. 4x MSAA is nice sufficient for VR.
  • Display screen House AA (SSAA)
    • SSAA has the excessive computational price however is ready to obtain the highest quality, 1.4x SSAA can also be utilized in Code51.

CPU efficiency optimization

CPU optimization can also be essential to the VR expertise to make sure constant and quick submits to the graphics pipe, and to stop stalling the VR scene rendering. To attenuate the CPU boundedness of DX11 VR recreation made with UE4, scale back render thread workload as a lot as attainable[6]. The RHI threads for DX11 in UE4 (4.20+) will assist scale back the CPU render thread overhead by means of D3D11 deferred rendering context[7], and it ought to be adopted each time attainable.

As well as, there are numerous approaches to optimize the render thread workload in UE4[8], the place a few of them are deployed in Code51:

  • Cut back drawcalls (higher lower than 2000 on Premium VR in keeping with our expertise for ahead rendering pipeline, the extra GPU is optimized (much less GPU computation time per body), the bigger this quantity will be)
  • Optimize visibility culling (InitView)
    • Modify belongings to cut back dynamic occlusion culling ({hardware} occlusion queries or hierarchical z buffer culling), for it’s computational inefficient to calculate visibility culling for an object that solely exhibits up a small portion of it on the display screen. An instance of this optimization is proven in Fig. 4
    • Use precomputed visibility culling[9] to cut back numbers of primitives wanted to be processed with dynamic occlusion culling in runtime. Nonetheless, it’s not so environment friendly in Code51 as a result of mechs can leap and fly within the recreation. The statically occluded primitives (~300 primitives) are 20% of the whole occluded primitives in Code51 when precomputed visibility culling is enabled
    • Masked Occlusion Culling (Github/Paper) is an occlusion culling approaches applied within the CPU with SIMD acceleration(SSE, AVX, and AVX-512), it’s an alternative choice to the hierarchical z buffer culling, which will be parallelized and effectively computed on fashionable multi-core CPUs
  • Cut back dynamic lighting, flip off shadow projection for dynamic lighting or use capsule shadows as an alternative when finances allowed
  • Use gentle baking as a lot as attainable
  • Use LOD & HLOD, hold tris < 2.5M for Premium VR
  • Use particle LOD and don’t use non opaque particles at LOD0

Fig. 4. An asset was modified from the left one to the correct one to keep away from culling calculation for objects behind the asset which will be seen by means of within the unique one.

Differentiation and deepening the immersive expertise

Final however not least, one key strategy to optimize the person expertise of VR apps is to make the most of all accessible computational sources on a {hardware} platform as a lot as attainable to be able to ship one of the best expertise on that platform.  Having nicely optimized CPU compute and better thread rely CPUs allows builders to make use of the CPU to deepen the VR immersion expertise.  For instance, a person with an Intel Core i7-7700Okay has extra CPU threads and sources to make use of than a person with an Intel Core i5-4590 solely (the minimal CPU spec. of Oculus Rift with out utilizing ASW). Thus the expertise of a VR app will be improved if additional CPU intensive visible and audial options are added to the app to devour these additional sources.

In Code51, we applied a number of CPU enhanced options to raised make the most of the CPU sources accessible on excessive finish Intel Core i7 CPUs. These options embrace 3D audio, object destruction, CPU particle enhancement and extra background results.

A lot of the CPU computation of the visible and audial enhancements is offloaded to the employee threads or the audio simulation thread in UE4, together with bodily simulation carried out by PhysX and ray tracing for physically-based sound propagation carried out by the Steam Audio plugin (occlusion and environmental audio). These sorts of options considerably enhance the immersion of Code51 on excessive finish CPUs with out efficiency drop since a lot of the computation is offloaded to the idle CPU cores, the place the affect to the essential path of the rendering (CPU render thread and GPU) is minimized.

Fig. 5 exhibits the body price knowledge of Code51 accordingly. The sport is ready to run easily on each Intel Core i7-7700Okay and Intel Core i7-7820HK with enhanced options on, however drops frames considerably on Intel Core i5-4590 with the identical setting, implying that the i5 CPU will not be capable of deal with all the improved options in 11.1ms per body. As an alternative, for customers with the min spec CPUs, they’ll nonetheless preserve a superb person expertise by turning off all the improved CPU options (low high quality setting). In keeping with the efficiency knowledge, Intel Core i7-7700Okay exhibits 27% efficiency profit in opposition to Intel Core i5-4590 by way of fps(body per second) when all CPU enhanced options are turned on in Code51.

Fig. 5. The body price of Code51 working on totally different CPUs (Intel Core i5 and  i7 processors) and high quality settings, the place Extremely Excessive is the one with CPU enhanced options and Low is the one with out. Take a look at methods:  Intel Core i5-4590, NVIDIA GTX1080, 2x4GB DDR3-1600, Home windows 10 model 1703; Intel Core i7-7700Okay, NVIDIA GTX1080, 4x4GB DDR4-2400, Home windows 10 model 1703; Intel Core i7-7820HK, NVIDIA GTX1080, 4x4GB DDR4-2400, Home windows 10 model 1703.

Fig.6 and seven present the GPUView screenshots of Code51 in Extremely Prime quality working on Intel Core i7-6800Okay with CPU cores set to 4C4T and 6C12T respectively utilizing msconfig, working on the identical CPU frequency. It’s apparent from the charts that on 4C4T configuration (a proxy to 4C4T Intel Core i5 processors), the rendering time of a body can’t attain 11.1ms and body dropping occurs on this case, whereas it could possibly run easily on 6C12T configuration.

Listed here are the chances of the CPU computation elevated on totally different threads of Code51 accordingly, working on the identical Intel Core i7-6800Okay in two configurations (6C12T and 4C4T) and noticed in Home windows Efficiency Analyzer (WPA):

Complete CPU workload:       43%↑

Render thread:                44%↑

Driver thread:                  10%↑

Sport thread:                  13%↑

Employee threads:               89%↑

A important quantity of the CPU works of the improved options was offloaded to the employee threads in Code51, resulting in the biggest computation enhance on these threads.

Fig. 6. A GPUView screenshot of Code51 on Extremely Excessive setting working on Intel Core i7-6800Okay and GTX1080. To reveal the scalable expertise conduct of Code51, the CPU cores have been set to 4C4T by msconfig on this case. Take a look at system:  Intel Core i7-6800Okay, NVIDIA GTX1080, 4x4GB DDR4-2400, Home windows 10 model 1703.

Fig. 7. A GPUView screenshot of Code51 on Extremely Excessive setting working on Intel Core i7-6800Okay and GTX1080. There is no such thing as a modification on CPU cores (6C12T) on this case, and Code51 employs the extra CPU compute sources to ship a richer immersive expertise. Take a look at system:  Intel Core i7-6800Okay, NVIDIA GTX1080, 4x4GB DDR4-2400, Home windows 10 model 1703.

Conclusion

Making VR customers really feel comfy and assuaging movement illness are two essential elements to the success of an e-Sports activities VR recreation. Solely video games with a protracted playtime and person habit can reach e-Sports activities. Code51 adopted varied approaches descripted on this article to cut back movement illness, and to deepen the immersive expertise, whereas on the identical time create a spectator mode that helps to enhance the viewing expertise for viewers. For efficiency optimization, render thread certain is normally the primary CPU bottleneck in UE4 DX11 VR apps in keeping with GPUView and WPA, commonplace recreation optimization strategies and offloading duties from the render thread to employee threads assist on this case, it’s additionally helpful to leverage all accessible CPU sources as a lot as attainable to make your recreation stand out from the group, by means of including extra CPU intensive options resembling these applied in Code51.

Click on right here to Be a part of the Intel® Sport Dev program totally free instruments, sources, and alternatives that will help you carry one of the best recreation expertise to the most important worldwide viewers

Supply: https://software program.intel.com/en-us/articles/Optimizing-the-user-experience-of-vr-games-on-ia-for-e-sports

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