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PowerVR is a division of Imagination Technologies (formerly VideoLogic) and is also their brand of 3D accelerators which is the most popular choice for portable 3D devices, but is no longer available in desktop PCs. The 3D accelerators are not manufactured by PowerVR, but instead the IP is licensed to other companies such as NEC.
The primary competitor to the PowerVR set of 3D chips in the late 1990s was the Voodoo series from 3dfx which would eventually become the market leader, before serious competition by ATI and NVIDIA expelled both companies from primary roles in the PC industry. Since 2002, many PC games no longer officially support the PowerVR.
Implementations
The Sega Dreamcast
The second generation PowerVR2 chip found a new lease of life in the Sega Dreamcast console between 1998 and 2001. As part of an internal competition at Sega to design the successor the Saturn, the PowerVR2 was licensed to NEC and was chosen ahead of a rival design based on the 3dfx Voodoo 2. Thanks to the performance of the PowerVR2, several Dreamcast games such as Quake III Arena could rival their PC counterparts in quality and performance.KYRO and KYRO II
In 2001, STMicroelectronics adopted the third generation PowerVR3 for their STG4000 "KYRO" and "KYRO II" chips. The STM PowerVR3 KYRO II, released in 2001, was able to rival the costlier ATI Radeon DDR and NVIDIA GeForce 2 GTS in benchmarks of the time despite not having hardware transform and lighting. Unfortunately, as games were optimised for hardware transform and lighting, the KYRO II lost its performance advantage and is not supported by most modern games.STM's STG5000 chip (right) was based upon the PowerVR4 which did include hardware T&L but it never came to commercial fruition.
PowerVR MBX
With the high end PC market secured by ATI and NVIDIA, PowerVR is now concentrating on the portable market with its latest design, the low power PowerVR MBX which has become the de facto standard for mobile 3D, having been licensed by six of the top ten semiconductor manufacturers including Intel, Texas Instruments, Samsung, Philips, Freescale, Renesas, and Sunplus.Products that use the MBX include:
Renesas SH7770 (SH-Navi I) -- MBX + VGP + FPU + SH-4, Renesas unidentified -- MBX + SuperH
- Mitsubishi Car Information Systems
- Pioneer Carrozzeria HDD CyberNavi AVIC-ZH900MD
- Alpine Car Information Systems
- Clarion Car Information Systems
Renesas SH73182 (SH-Mobile3) -- MBX Lite + SH-4, Renesas SH73230 (SH-MobileA) -- MBX Lite + SH-4, Renesas SH-MobileG -- MBX Lite + SH-4
- Fujitsu F901iC
- Mitsubishi D901i
- Fujitsu F902i
- Mitsubishi D902i
- SK Teletech (SKY) IM-8300
- Pantech PN-8300
- Helio Hero
- Motorola MS550
- Mitsubishi D851iWM (MUSIC PORTER X)
- Mitsubishi D702i
- Fujitsu F902iS
- Mitsubishi D902iS
Renesas SH3707 -- MBX + VGP + FPU + SH-4
- Sega Sammy Aurora
Intel 2700G (Marathon) -- MBX Lite (as a companion to the Intel XScale processor PXA27x)
- Dell Axim X50v
- Dell Axim X51v
- Pepper Pad
- Pepper Pad Plus
- Advance Tech M.A.G.I.C.
- Dresser Wayne iX Fuel Dispensers
Texas Instruments OMAP2420 -- MBX + VGP + FPU + ARM11
- NEC N902i
- Panasonic P902i
- Sharp SH902i
- Sony Ericsson SO902i
- Nokia N93
- Panasonic P702i
- Sharp SH702iD
- NEC N902iS
- NEC N902iX HIGH-SPEED
- Panasonic P902iS
- Sharp SH902iS
- Sharp DOLCE SL (SH902iSL)
- Sony Ericsson SO902iWP+
Texas Instruments OMAP2430 -- MBX Lite + VGP Lite + FPU + ARM11
Texas Instruments OMAPV2230 -- MBX Lite + FPU + ARM11
Texas Instruments OMAP3430 -- MBX Lite + VGP Lite + ARM Cortex-A8
Philips Nexperia PNX4008 -- MBX Lite + ARM9
- Sony Ericsson P990
- Sony Ericsson M600
- Sony Ericsson W950i
- Sony Ericsson M608c
Freescale i.MX31 -- MBX Lite + FPU + ARM11
Samsung S3C2460 -- MBX Lite + FPU + ARM9
The Technology
The PowerVR chipset uses a unique approach to rendering a 3D scene, known as Tile Based Deferred Rendering (often abbreviated as TBDR). As the polygon generating program feeds triangles to the PowerVR driver it stores them in memory in triangle strip format. Unlike other architectures, polygon rendering is not performed until all polygon information has been collated for the current frame - hence rendering is deferred.
In order to render, the display is split into rectangular sections in a grid pattern. Each section is known as a tile. With each tile is associated a list of the triangles that visibly overlap that tile. Each tile is rendered in turn to produce the final image.
Tiles are rendered using a process similar to ray tracing. Rays are cast onto the triangles associated with the tile and a pixel is rendered from the triangle closest to the camera. The PowerVR hardware calculates the depths associated with each polygon for one tile row in 1 cycle.
The advantage of this method is that, unlike with a more traditional z buffered rendering pipeline, work is never done determining what a polygon looks like in an area where it is obscured by other geometry. It also allows for correct rendering of partially transparent polygons independent of the order in which they are processed by the polygon producing application. However, this capability was only implemented in Series 1 and 2. It has been removed since for lack of API support and cost reasons. More importantly, as the rendering is circumscribed to a tile at a time, the whole tile can be in fast onchip memory, which is flushed to video memory before passing on to render the next tile. Note that, under ideal circumstances, each tile only needs to be visited once per frame.
PowerVR is not the only pioneer of tile based deferred rendering, but the only one to successfully bring a TBDR solution to market. Microsoft originally conceptualised the idea with their abandoned "Talisman" project. Gigapixel, a company that developed IP for tile based deferred 3D graphics, were bought by 3Dfx, who were subsequently bought by Nvidia. Nvidia has no official plans to pursue tile based rendering at current.
Intel uses a similar concept in their integrated graphics solutions. However, their method, coined Zone Rendering, does not perform full hidden surface removal (HSR) and deferred texturing, therefore wasting fillrate and texture bandwidth on pixels that are not visible in the final image.
Recent advances in hierarchical z buffering have effectively incorporated ideas previously only used in deferred rendering, including the idea of being able to split a scene into tiles and of potentially being able to accept or reject tile sized pieces of polygon.
PowerVR Chipsets
Places PowerVR technology and its various iterations have been are:
Series 1
| Product | Type | Chip Name | Clock Rate |
|---|---|---|---|
| Apocalypse 3d/3dx | 3D PC add-in board | PCX-1 and PCX-2 | 66 MHz |
Series 2
| Product | Type | Chip Name | Clock Rate |
|---|---|---|---|
| Sega Dreamcast | console | CLX2 | 100 MHz |
| Neon250 | 2D/3D PC add-in board | PowerVR 250PC | 125 MHz |
| Naomi Arcades | set top boxes | CLX2 | 100 MHz |
| Naomi2 Arcades | set top boxes | 2 CLX2s + ELAN | 100 MHz |
Series 3 (STMicro)
| Product | Type | Chip Name | Clock Rate |
|---|---|---|---|
| KYRO | 2D/3D PC add-in board | STG4000 | 115 MHz |
| KYRO II | 2D/3D PC add-in board | STG4500 | 175 MHz |
| KYRO IISE | 2D/3D PC add-in board | STG4800 | 200 MHz |
Series 4 (STMicro)
KYRO 3 (2D/3D AIB) product shelved due to STMicro selling graphics division.Series 5
Earlier Version (PC/arcade) shelved due to a lack of partner for the PC market and never being employed by licensee Sega Sammy for their arcade system.SGX (next generation fully programmable unified shader architecture):
- exceeding requirements of OpenGL 2.0 and DirectX9 Shader Model 3.
- licensed to Intel, Renesas and NEC
- 3 variants announced for the handheld mobile market: SGX510, SGX520, SGX530
- Company presentation shows Thalia-L (consumer/automotive), Muse (portable computing), and Athena (desktop computing) cores in the SGX roadmap
Mobile
- PowerVR MBX/MBX Lite
- PowerVR SGX (pixel and vertex shader hardware)
References
External links
"PowerVR"