Dynamic Resolution Rendering

Transcription

1 Dynamic Resolution Rendering Doug Binks, Intel Leigh Davies, Josh Doss, Matt Fife, Philipp Gerasimov, Axel Mamode, Steve Mccalla, Phil Taylor, Jeff Williams, and many more in VCSE 1

2 Resolution selection is one of the defining aspects of PC Gaming. VIDEO SETTINGS Select Resolution: <1280x720> 2

3 Resolution selection is one of the defining aspects of PC Gaming. VIDEO SETTINGS Select Resolution: <1280x720> 3

4 Introduction Dynamically adjust the resolution of 3D scene to meet performance and quality goals Render Graphical User Interface at screen resolution Performance results and demos will be shown for the 2nd generation Intel Core processor family (codenamed Sandybridge) with Intel GMA HD3000 graphics. 4

5 The User Interface is important Trion Worlds RIFT: Planes of Telara MMO with Scaleform GFx UI In game GUIs very important to MMOs, RPGs, RTSs. Menus can get quite populated (e.g. multiplayer game browsers) Good to have a high resolution to include lots of content Natural resolution of screen preferred for clear text 5

6 6 Many thanks to Landyn Pethrus and <Wicked Mojo> of Black Dragonflight for this screenshot from Activision Blizzard s World of Warcraft showing how important the GUI can be to game play.

7 Performance Many games GPU bound Titles are becoming increasingly pixel bound: Post process effects Complex shading Deferred lighting Leads to resolution dependency Large variance in PC capabilities & monitor resolutions Few users adjust settings 7

8 Quality Quality includes frame rate and responsiveness Users perception and weighting of quality metrics varies with usage: Moving / Zooming on Google Maps / ipad prefers responsiveness over image quality whilst handling input PC Games may have uncertain performance dependencies Dynamic Resolution can help with runtime performance adjustments Can use anti-aliasing techniques and super-sampling to improve quality when performance sufficient 8

9 Motivation IV: Power Mobile systems becoming predominant. User could switch from plugged in to battery, or run low on power With Dynamic Resolution can lower resolution on the fly and limit FPS to reduce power consumption. 0.5x resolution on demo cuts SNB package (CPU+GPU+System Agent) overall power to ~0.7x normal with vsync enabled. Performance settings may throttle frequency, so need to lower demands to match new levels. 9

10 Sub-Sampling - Basic principle Render scene to smaller resolution render targets Upscale scene to back buffer Render GUI at full resolution Basic upscale adds 1 texture sample + 1 FB write per back buffer pixel, approx 1ms at 1280x720 on SNB but cost can be amortized with other operations. Several games use this technique on consoles: Halo 3 for example. Render 3D 3D Render GUI 3D + GUI Conventional Render 3D 3D Upscale 3D Render GUI 3D + GUI Sub-sampling 10

11 Use the Viewports to vary resolution Viewport 3D Render Target For example Render Target of 1920x1080 Viewport origin (0,0) size (1280,720) No need to change anything else when rendering to this Except for reads from a dynamic RT bound as an input, where we need to scale the texture coordinates 11

12 3D Render 3D Dynamic Resolution 3D Render 3D Scale 3D Render GUI 3D + GUI Sub-sampling Dynamically vary resolution by rendering into a larger render target and constraining rendered area using viewport. Scale 3D Render GUI 3D + GUI Super-sampling 12

13 Sample Renderer Simple forward renderer with motion blur post process More driver and vertex dependant than many games complex geometry scene with no LOD no zoning / scene database system no optimization of draw call order So your performance results will probably be better! 13

14 Basic Upscale Filtering Comparisons Point filtering Bilinear filtering Bicubic filtering Christian Sigg, Martin Hadwiger, Fast Third Order Filtering, GPU Gems 2. Addison-Wesley, Point + film grain style noise Point + noise offset texture coordinates 14

15 Dynamic Rendering Off 18.0ms

16 Dynamic Rendering On Resolution 100% of back buffer (no scaling) Point Filtering 19.2ms

17 GUI Resolution same as before 3D Resolution 71% 12.6ms

18 PS Clear 12.5ms

19 Bilinear Filtering 12.5ms

20 Bicubic only noticeably different to bilinear for large up-scaling (scale << 50%) Bicubic Filtering 15.6ms

21 Noise Filtering 12.7ms

22 Noise Offset Filtering 12.8ms

23 1:1 copy without scaling or filtering. Black region not copied (PS clear would not clear this from original RT). No Filter / Scaling (debug) 12.8ms

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25 OFF 16.2ms

26 ON 10.8ms

27 Temporal Anti-Aliasing Jitter (offset) every other frame by 0.5 pixels in X and Y Use translation of projection matrix Scale filter combines two frames use offset texture coordinates for jittered frame sampling Get 2x the number of pixels Resulting pattern is often termed Quincunx Time Frame 3D Render Final Image 27

28 Temporal Anti-Aliasing with Dynamic Resolution Gives increased final resolution when using smaller dynamic resolution buffer 2x pixels per unit area, so observed resolution increased Not just anti-aliasing, improves observed detail Results in low cost AA when dynamic resolution equal or larger than screen resolution Final pixel seen by player is a sum of >1.0 pixels from scene Not just anti-aliasing, increased texture and shader detail 71% Resolution Point Filter 71% Resolution Temporal AA 100% Resolution Point Filter 100% Resolution Temporal AA 28

29 Dynamic Rendering Off 18.0ms

30 Use texture LOD offset of -0.5 during scene render Dynamic Rendering On with Temporal AA 13.1ms

31 Intelligent Temporal Anti-Aliasing Scale previous color with Velocity to eliminate motion artefacts (ghosting). S 1 K ( V ( C C n n S C (1 S) 1 V V n n 1 ) n 1 V n 1 ) Where C is the final color output. C V n n the current and C n 1 is the current and V the p revious color render target. n 1 the p revious velocity buffers. The constant K is typicallysized to be ~1/width. 31

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33 Some ghosting in high contrast areas, can be tuned via K Improved edges More texture & shading detail

34 Super-Sampling Can also use super-sampling. Some GPUs may not have sufficient memory for large Render Targets Sandy Bridge has lots of memory as it uses system memory Can readily adjust resolution to get best image at desired frame rate, e.g. 30FPS 34

35 Super Sampling disabled 21.2ms

36 Super Sampling enabled Enabling SS has a low impact on performance when using PS clear Resolution 100% of back buffer (not increased yet) 21.7ms

37 Even better edges 132% Resolution 30FPS target

38 What filter to pick? D3D11_FILTER_MIN_LINEAR_MAG_MIP_POINT Sub-Sampling upscaled via point sampling Super-Sampling needs linear filter to average pixels Temporal Anti-Aliasing low cost, good quality option Use D3D11_SAMPLER_DESC MipLODBias of -0.5f during 3D Scene Pass Add noise and/or noise offset sampling to for subsampling if this suits art style Could also additionally use MSAA (more difficult for deferred renderers) 38

39 Further filter tricks Improved filtering: Morphological Anti-Aliasing (MLAA) Temporal Anti-Aliasing with distance to pixel center weighting and motion compensation Weight filtering method on location on screen: Better filter used where mouse / target reticule is Better filtering on region where main character is Use depth of field to assist filter choice 39

40 Complex Resolution Schemes Can render different passes at different resolutions Geometry pass at high resolution, lighting & post process at another (sometimes called Subpixel Reconstruction Anti- Aliasing) Render particles to an even lower resolution buffer (already used in several games) Can also use hybrid resolutions within a pass Hyunwoo Ki, Multi-Resolution Deferred Shading, Game Programming Gems 8. Boston: Charles River Media

41 Performance Results Can achieve a wide range of performance / quality using technique. 41

42 FPS 300 Dynamic Resolution % of Resolution of Back Buffer (1280x720) Pixel area is square of this value 100% Point Point + PS Clear TAA + PS Clear Point + PS Clear + SS Enabled TAA + PS Clear + SS Enabled Theoretical Maximum 42

43 Dynamic Resolution RT as Texture Care needs to be taken using a dynamic RT as texture Need to use adjust RT texture coordinates based on current viewport Need to guard against dependant reads to area outside rendered RT Clearing Render Targets with pixel shader is faster than full RT clear when using <~0.8x resolution scaling at 1280x720 (but keep normal Depth Stencil clear) May not need clear in many cases 43

44 MB right / bottom error due to lack of clamp Clamp all dependent reads: //clamp velocity to texture size float2 clampedpos = min( input.tex0.xy - velocity, g_pssubsamplertcurrratio.xy ); velocity = -( clampedpos - input.tex0.xy ); Clear colour leak Clear colour leak 44

45 Potential issues / improvements Shadow map rendering resolution may also need to be scaled Object LOD, culling and shading LOD can be linked to resolution, taking care to limit popping If performance is too low, may still require resolution switch 45

46 Resolution Control Approaches Frame time based Adjust resolution to hit performance target Use combination of overall frame time and GPU timings Ignore overall frame time if it s high could be full-screen to windowed switch etc. Frame complexity based Use metric for anticipated FPS Frame time + Camera motion 30 FPS when camera moving slowly, cut scenes etc. Rapidly moving objects may need geometry based motion blur techniques; many games already happy with this FPS 60 FPS during rapid camera movement 46

47 The Future / Speculation Render some content at higher resolution within a given pass Not easy for general 3D scene, problems: Transparencies Post Processing 47

48 Conclusion Dynamic resolution gives you the tools to improve overall quality with minimal user intervention 48

49 Call to Action Come to the Intel booth and check it out! Add dynamic resolution to your game Investigate using Temporal Anti-Aliasing Get in touch, ask me question! 49

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51 Optimization Notice Optimization Notice Intel compilers, associated libraries and associated development tools may include or utilize options that optimize for instruction sets that are available in both Intel and non-intel microprocessors (for example SIMD instruction sets), but do not optimize equally for non-intel microprocessors. In addition, certain compiler options for Intel compilers, including some that are not specific to Intel micro-architecture, are reserved for Intel microprocessors. For a detailed description of Intel compiler options, including the instruction sets and specific microprocessors they implicate, please refer to the Intel Compiler User and Reference Guides under Compiler Options." Many library routines that are part of Intel compiler products are more highly optimized for Intel microprocessors than for other microprocessors. While the compilers and libraries in Intel compiler products offer optimizations for both Intel and Intel-compatible microprocessors, depending on the options you select, your code and other factors, you likely will get extra performance on Intel microprocessors. Intel compilers, associated libraries and associated development tools may or may not optimize to the same degree for non- Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include Intel Streaming SIMD Extensions 2 (Intel SSE2), Intel Streaming SIMD Extensions 3 (Intel SSE3), and Supplemental Streaming SIMD Extensions 3 (Intel SSSE3) instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. While Intel believes our compilers and libraries are excellent choices to assist in obtaining the best performance on Intel and non-intel microprocessors, Intel recommends that you evaluate other compilers and libraries to determine which best meet your requirements. We hope to win your business by striving to offer the best performance of any compiler or library; please let us know if you find we do not. Notice revision #

52 Appendix I Visual Computing Home Page Threading Building Blocks: Graphics Performance Analyzers: Graphics Samples Home Page Keep up to date with samples releasing throughout the year Graphics Samples Page: Sandy Bridge Samples Page: 52

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