Imagination Technologies Interview: Photorealistic Gaming On Mobiles And Tablets

Imagination Technologies are at the forefront of providing silicon and software for the entertainment and consumer industries. Their PowerVR range of products are quite a rage among mobile and tablet products and they are consistently innovating in the latest GPU/CPU and ray tracing technologies.

GamingBolt got in touch with Alex Voica who is a part of the Marketing Communications team at Imagination, to know more about the various product offerings.

Rashid Sayed: To begin with, tell us about yourself and Imagination?

Alex Voica: First of all, thank you for this opportunity and the chance to answer a set of very interesting questions! My name is Alex Voica and I am part of the Marketing Communications team at Imagination. Even though I started my career as a CPU engineer, I have since branched out into technology PR. I write for our blog (http://blog.imgtec.com/author/alexvoica), manage our social media channels and attend some of the biggest events and conferences worldwide where I talk to journalists, analysts and consumers about our technologies.

One of the many reasons for joining Imagination is the absolutely amazing breadth of technologies we design.

We split our product lines in four main families: multimedia, general purpose processors, communications and cloud technologies. Your readers are perhaps familiar with our PowerVR Rogue and SGX GPUs, but our multimedia IP includes highly popular video, vision and ray tracing IP too. We have recently acquired MIPS and are now designing and licensing a wide range of 32- and 64-bit CPUs. Additionally, we are one of the leading providers of solutions for Wi-Fi, IoT and always connected devices through our Ensigma communications IP,Caskeid technology for connected audio products and the FlowClouddevice-to-cloud software platform.

"PowerVR Ray Tracing is a revolutionary technology that brings very fast ray tracing to the world's leading mobile GPU. This game-changing feature enables astonishing realism as well as allowing developers and content creators to simplify their workflow."

Rashid Sayed: Can you briefly describe what is Imagination involved in these days?

Alex Voica: Because our product portfolio is so rich and diverse, we are active in a variety of mobile and embedded markets, including mobile multimedia and computing, home electronics, automotive, networking, security, healthcare, smart metering and many others.

Imagination’s technologies are at the heart of a broad range of products from the latest mobile phones and tablets to IoT and wearables, and also enable exciting applications for imaging, augmented reality, gaming and more.

New Imagination IP products unveiled recently include PowerVR V2500, the first imaging processor IP core based on the innovative PowerVR Raptor architecture, PowerVR GX6650, the powerful GPU which redefines performance in mobile with 192 ALU cores, and theMIPS Warrior M51xx processors, the world’s first MCU-class CPU IP cores with hardware virtualization, which provide advanced security and reliability.

Rashid Sayed: Imagination was at GDC this year and one of the biggest revelations was the PowerVR Ray Tracing. Can you tell us a bit about how this technology works?

Alex Voica: PowerVR Ray Tracing is a revolutionary technology that brings very fast ray tracing to the world’s leading mobile GPU. This game-changing feature enables astonishing realism as well as allowing developers and content creators to simplify their workflow.

A main use for PowerVR Ray Tracing in rendering is to accurately simulate the transport of light. In 3D graphics, rendering a surface means looking at how much of a scene is visible to the camera. The physics of light dictate that the properties of a surface are not enough for a correct and realistic renderer; one needs to know the properties of the entire scene.

Ray tracing is a powerful tool that adds an innate understanding of light to the GPU. Therefore, some effects are more efficiently computed with ray tracing than using state of the art raster techniques. Example use cases for ray tracing include pre-baked lighting, hybrid rendering or fully ray traced rendering.

The PowerVR Wizard family of GPUs that we have announced at GDC 2014 delivers a highly optimized and ultra-efficient hardware implementation of the PowerVR Ray Tracing technology. The first member of this family is PowerVR GR6500; this ray tracing GPU includes additional ray tracing-specific hardware that provides full hardware acceleration of the entire ray tracing flow, including model building and traversal:

– a dedicated ray tracing data master that feeds ray intersection data to the main scheduler, in preparation for shaders to run, which evaluate the ultimate data contribution from the ray.
– a specialized Ray Tracing Unit (RTU) which uses fixed-function math to perform ray tracing intersection queries, in addition to gathering ray coherency in order to reduce power and bandwidth consumption.
– a scene hierarchy generator to speed up dynamic object updates.
– a frame accumulator cache that provides write-combining scattered access to the frame buffer.

All of these ray tracing-specific elements have been designed to integrate efficiently and communicate perfectly with the rest of the GPU architecture and produce real-time, interactive ray traced graphics that can comfortably scale from mobile and embedded platforms to gaming consoles and mainstream gaming PCs.

"If you look at where innovation and growth for graphics is happening right now, most of that is coming from mobile. For the better part of the last two decades, Imagination has focused on licensing IP the mobile market since this business model is how we can best use our expertise to deliver highly optimized solutions for our partners and consumers."

Rashid Sayed: How do you think PowerVR Ray Tracing could potentially change video game graphics?

Alex Voica: Even though most people think ray tracing is only useful for non-real time photorealistic, physically accurate rendering for things like movies and adverts, there is absolutely no reason why it cannot be used in real-time renderers for games, especially since there is now efficient hardware support for accelerated ray tracing in the PowerVR Wizard GPU family.

The main use for ray tracing in rendering is to accurately simulate effects such as hard and soft shadows, transparency, reflections or refractions. All these ray tracing-based effects are easy to implement, they do a better job approximating the physical light transport phenomena, and they avoid the artefacts of even the more sophisticated raster techniques.

Additionally, they can be more efficient. Ray traced shadows allow for per-pixel sampling decisions so there is much less waste in scenes with many shadow casting lights. Moreover, ray tracing reflections are a big win over using dynamic reflection maps in scenes with many reflective objects. This is because there is no need to perform a separate rendering pass for each object when you can trace rays for the pixels that are visible.

While the primary application of ray tracing is rendering, there is nothing that prevents it from being used for other purposes. There are many applications that would benefit from the ability to know the entire layout of the scene and can use ray tracing independent of rendering; physics and collision detection or visibility detection in AI are two perfect examples.

For example, characters in a first-person shooter can start to see and understand the 3D environment around them, using the ray tracing to process spatial understanding. Thisopens up a new world for realistic behavior when in-game agents can make decisions based on direct line of sight calculations that model what they are able to see.

Rashid Sayed: There is a lot of talking regarding Ray Tracing technology being used for PS4 and Xbox One. But in reality no one is able to implement it yet. I find this situation quite surprising since the new consoles are more capable than mobile/tablets. What is your opinion on the same?

Alex Voica: Actually, ray tracing is used quite a lot in the back-end of the game creation process for visualization, generating cut-scenes and creating pre-baked lighting.

If you look at where innovation and growth for graphics is happening right now, most of that is coming from mobile. For the better part of the last two decades, Imagination has focused on licensing IP the mobile market since this business model is how we can best use our expertise to deliver highly optimized solutions for our partners and consumers.

The latest PowerVR Series6XT GPU family delivers raw performance that matches (or in some cases, even exceeds) the levels of previous generation consoles such as the Xbox 360 or PlayStation 3.

The newly launched PowerVR Wizard GPUs can comfortably scale from single core, multi-cluster configurations for mobile and embedded platforms to multi-core, multi-cluster versions that would power gaming consoles and mainstream gaming PCs.

We are and have always been open to working with any silicon vendor that wishes to implement our technology in any form factor. Additionally, all of our GPUs are uniquely designed to work with any leading CPU architecture, including MIPS.

"Importantly, PowerVR Series6 GPUs have recently passed OpenCL 1.2 conformance and are designed to support OpenGL ES 3.1 which means developers will have access to the latest compute and graphics mobile APIs from the Khronos Group."

Rashid Sayed: Tell us how PowerVR Ray Tracing takes advantage of Unity 5, specially given that Unity 5 now has Geomerics integration?

Alex Voica: Before Unity 5 was released, the process of pre-baking lighting information was usually done in a slow iteration cycle which meant that developers and artists had to compromise between fewer cycles (leading to lower quality) or paying a time penalty for accurate lighting. This caused frustration for a lot of developers and artists who couldn’t access high-performance server farms on which to run these iterations.

Enter PowerVR Ray Tracing from Imagination, offering an interactive preview of global illumination straight from the new Unity 5 lightmap editor. Our technology delivers unbiased physically based global illumination (GI) and instant feedback on any changes developers make to the scene, including geometry changes.

Together with Unity, we’ve worked on a feature for Unity 5 that will show lightmaps or update materials interactively, refreshing geometry and lights as you move around the scene.We’ve spent a lot of time getting this feature working fast and matching the exact Enlighten output, saving userstime and money.

Rashid Sayed: Tell us about PowerVR Series6. What kind of improvement have you made from the previous versions?

Alex Voica: PowerVR Series6 has recently started to ship in mass volume with both 32- and 64-bit platforms. This family of GPUs moves away from the MP (multi-processor) approach we took with PowerVR Series5XT and adoptsmulti-cluster scalability which delivers significant improvements in performance, area and power efficiency.

Importantly, PowerVR Series6 GPUs have recently passed OpenCL 1.2 conformance and are designed to support OpenGL ES 3.1 which means developers will have access to the latest compute and graphics mobile APIs from the Khronos Group.

We have also added a number of features that deliver advanced functionality for high-resolution devices and reduce memory bandwidth and power consumption. For example, PowerGearing is an advanced power management technique that includes a combination of automatically enabling clock gating, enabling/disabling power to clusters, and intelligently using the Microkernel firmware to offer lower latency workload feedback into DVFS (dynamic voltage and frequency scaling) and power management decision process.

Select PowerVR Rogue GPUs offer a technology called PVR3C (PowerVR Triple Compression) which includes PVRGC (lossless geometry compression to manage the increasing geometry complexity of scenes), PVRTC™ (the market leading lossytexture compression to handle increasing texture counts and sizes) and PVRIC (lossless framebuffer compression to handle system level bandwidth due to the ever increasing size of render targets both on-screen and off-screen).

Finally, all Power Rogue GPUs rely on desktop-class scalar processing, which achieves the highest utilization of ALUs and eases graphics programming. Whereas vector arithmetic units occupy more silicon than a scalar unit and might not be fully used if code is not operating on vectors, scalar ALUs handle algorithms written with scalar ops (R), vec2 ops (RG), vec3 (RGB) or a full vec4 (RGBA) with the same efficiency. In addition, scalar instructions decrease the complexity of the instruction set, requiring less chip area for the instruction decoder. Trust me, that’s a good thing.

Rashid Sayed: Can you share specifications for PowerVR Series6?

Alex Voica: Sure, in fact we’re really excited about the performance capabilities of the new Rogue ranges. The PowerVR Series6 family has five members: PowerVR G6200 and G6400are two and four-cluster GPUs, respectively,designed to offer the best performance while also keeping the smallest area possible and staying true to our ultra-low power approach. PowerVR G6230, G6430 and G6630 are respectively two, four and six cluster GPUs that go all out, including the best possible mix of performance and features.

PowerVR Series6 GPUs include a number of Unified Scalable Clusters (or USCs); each cluster contains 16 pipelines and each pipeline has 2 FP32 ALUs. For example, PowerVR G6230 is a dual-cluster GPU that has a total of 64 FP32 ALU cores, offering superior processing power and improved precision for better image quality in console-quality games. The PowerVR G6230 GPU also includes a number of FP16 cores which provide additional low-power performance for a range of graphics applications, including fast blending for HDR rendering in games and UIs.

At a target frequency of at 600MHz, this translates into up to 115.2 FP16 GFLOPS and up to 76.8 FP32 GFLOPS maximum performance.

"Our FlowCloud technology is primarily designed to connect devices to the internet, enabling easy product registration and updates as well as access to partner-enabled services. Developers could use it to easily enable multiplayer games or help developers create better, more secure in-app payment services."

Rashid Sayed: Do you think with the PowerVR Series 6, you will be able to surpass visuals and physics that are possible on the PS4 and Xbox One?

Alex Voica: For now, comparisons between mobile and desktop-class devices are difficult since smartphones and tablets are usually designed according to very different specifications compared to a PC or a game console. It tends to get very subjective, but certainly many mobile devices are as visually compelling as their tethered counterparts.

When it comes to performance in mobile, there are other considerations apart from CPU and GPU raw performance metrics that need to be taken into account. Even if current high-end Rogue GPUs can match the graphics performance of previous generation consoles, the overall system performance is still influenced by factors like heat dissipation and memory bandwidth.

Instead, we focus on delivering the best possible performance per mW and mm2. In fact, I would say that this is where a lot of the innovation is currently happening: squeezing the most out of the power budget you have by using advanced techniques like PowerGearing, PVR3C or FP32/FP16 mixed-mode ALUs.

Rashid Sayed: I also wanted to ask whether the PowerVR Series 6 supports hardware virtual texturing and how does it work?

Alex Voica: Since no mobile games currently make use of hardware virtual texturing, PowerVR Series6 GPUs do not currently support this feature.

Rashid Sayed: PowerVR Series 6 supports DirectX11.1 and it’s obvious it will support DirectX12 next year. How do you think this will affect PowerVR series? Furthermore, what are your thoughts on how DX12 can potentially change the game development scene?

Alex Voica: PowerVR Rogue GPUs can scale up to DirectX11.1 but we are now actively supporting the feature set that is most relevant for our customers in mobile: DirectX 9_3 and 10_0.

Rashid Sayed: I am intrigued by FlowCloud technology. Do you think it can be used to improve the graphics and physics on mobiles/tablets byoffloading complex calculations on a remote server? Microsoft is also planning to do the same thing with Xbox One but I am assuming that they are facing issues since not everyone has a high speed broadband connection. But for you guys it might be doable since everyone these days have 3G or 4G connections on their mobile/tablets. What are your thoughts on this?

Alex Voica: Our FlowCloud technology is primarily designed to connect devices to the internet, enabling easy product registration and updates as well as access to partner-enabled services. Developers could use it to easily enable multiplayer games or help developers create better, more secure in-app payment services.

When it comes to offloading computational resources to the cloud, the main issue is related to bandwidth availability. When you are inside your home, connecting your tablet and your game console over Wi-Fi is easy so you could combine the two processors in a mesh and exploit both of their potential computational performance, though you might never reach peak performance due to network bottlenecks.

However, when you are on the move, relying on a 3G connection to offload real-time rendering to the cloud is unrealistic. From an infrastructure perspective, this would be very difficult to coordinate between carriers and gaming companies, since there are no standards and no way to control bandwidth or to allocate separate channels for this type of streaming at the moment.

This is why we believe computing will rely on delivering the best possible performance from low power application processors that reside in the devices you carry with you: your smartphone, tablet, or laptop.

We have very compelling technologies for both GPU and CPU racks so we are well prepared if this becomes a meaningful market in the future.

Rashid Sayed: I find it interesting that your MIPS64 Architectures are available for gaming consoles but as far as I know they are not being used. Can you tell us about its specifications [number of cores, clock speed etc.] and how is better than the ones found in the PS4 and Xbox One?

Alex Voica: Perhaps the most popular game consoles to use a 64-bit MIPS architecture based CPU werethe PlayStation 2 and PlayStation Portable.

The new line-up of MIPS Warrior CPUs includes both 32- and 64-bit designs. The current performance leader of the Warrior pack is the P5600, a very credible candidate for high-performance, low-power Android-based game consoles. MIPS P5600 has been designed to be a leader in high performance and power efficiency for 32-bit CPU IP. It offers 1.2 – 2x more system performance (single thread performance exceeds 5 CoreMark/MHz and 3.5 DMIPS/MHz per core) than its proAptiv predecessor in a similar mobile-focused power envelope, and supports peak frequencies above 2GHz on TSMC’s 28HPM process node.

We have designed the P5600 CPU to work in a fully coherent multicore system that can include up to six individual processors per single cluster, achieving 35,000 DMIPS and 50,000 CoreMark at 1.7 GHz.

Rashid Sayed: I wanted to ask how are you handling potential bottlenecks between CPU and GPU in case of mobile/tablet gaming

Alex Voica: We think that heterogeneous SoCs are the future of mobile. There are several optimizations you can do at the CPU and GPU level to provide a true heterogeneous processor, however these processors havedistinct datapath architectures, each very different in ISA and capabilities.

That’s where technologies such as HSA (Heterogeneous System Architecture) come in. The HSA Foundation was created by industry leaders including AMD, Imagination, MediaTek, Qualcomm and Samsung, to ensure that applications can manage their execution not only on the CPUs and GPUs in a system, but also the infrastructure connecting them.

By creating an open standard around how to connect CPUs to GPUs and other processors, we can break the dependence of such advanced apps on any particular chip or CPU or GPU architecture. This enables the silicon industry to innovate by allowing multiple vendors to create competing solutions – fuelling the innovation the semiconductor industry is so famous for.

Rashid Sayed: As a final question, I wanted to ask where do you see mobile/tablet gaming in the next five years? What kind of improvements are you expecting to see?

Alex Voica: Since we are right at the heart of the user experience, we have a very good understanding of where mobile technologies, including gaming, are headed.

Thanks to technologies like PowerVR Ray Tracing, we expect games to approach photorealistic image quality and run faster and smoother. Because our focus has always been on developing extremely power efficient solutions, end users will be able to play the most demanding games for longer, without their devices getting too hot or unstable.

Finally, as devices incorporate more high-performance processors and APIs get more feature-rich, we expect to see a blurring of lines between console and mobile-class games to the point where developers would be able to port titles across different devices with minimal effort.

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