FIC A97P Radeon 9700 Pro review



Radeon 9700 Pro Features


Hyper Z III

The Radeon 9700 Pro features an updated implementation of Hyper Z: Hyper III. The goal of Hyper Z to save bandwidth, which in turn will provide improved performance. Most manufacturers include similar such technologies now, e.g. NVIDIA’s Lightspeed Memory Architecture or PowerVR’s Tile Based Rendering. Conversely Matrox’s Parhelia graphics cards feature no bandwidth saving technologies & as such despite massive bandwidth performance is lacking against many other graphics cards that feature comparatively less bandwidth, but do feature bandwidth saving technologies. The main components to Hyper Z III are:

Hierarchical Z This would perhaps be the main “meat” to Hyper Z, the aim of which is to reduce the level of overdraw during rendering. It’s referred to as hierarchical as the Z-Buffer is divided into (3 levels of) tiles upon which the depth tests are then carried out to determine visibility of objects & whether rendering should occur or not. Hyper Z III further enhances this by adding an Early Z Test allowing depth comparisons to be made against the display resolution Z-Buffer should it pass the Hierarchical Z-Buffer tests. Hierarchical Z requires no specific application support, though performance benefits can vary depending on rendering order, with Front to Back potentially yielding the best performance & Back to Front yielding least gains. Most Games however use a Random rendering order, the benefits of which tend to lie somewhere between in between the 2 previous rendering orders. It is also probably worth noting that Hierarchical Z is not as efficient as PowerVR’s tile-based deferred rendering.

Z Compression The Z-Buffer contains depth information for every pixel to be rendered. Thus using higher resolutions not only consumes more fill rate, it also requires a larger Z-Buffer as more pixels are to be rendered. Hyper Z III however supports compression of the Z-Buffer, which reduces the size of this data & therefore will save on bandwidth needed for Z-Buffer reads/writes. With FSAA enabled colour compression is also supported. As such this compression helps makes the Radeon 9700 Pro a highly efficient card when rendering with FSAA enabled in particular & ATI claims that at best it offers at 24:1 compression ratio with 6X FSAA (4:1 with FSAA disabled). Perhaps most critically this Z Compression is lossless & there should be no adverse effect on image quality as a result. No application support is required for this.

Fast Z Clear Normally clearing the Z-Buffer (which needs to be done for each frame rendered) is performed by writing 0s throughout it. With Fast Z Clear this process is made significantly more efficient by tagging blocks of the Z-Buffer as cleared (ATI claims this uses only 1/64 the resources over Fast Z Clear disabled). No application support is required for this feature.


Truform 2

Truform 2 represents ATI’s Higher Order Surface support features. This takes the form of N-Patch support, & with Truform 2 – Displacement Mapping support as well – both are means of achieving the same goal – increasing the level of geometry (For more complex appearing shapes). N-Patch support has been refined a bit further & now supports continuous, adaptive tessellation. N-Patch support is available in several Games at this point & to illustrate the intended effects of this I used Soldier of Fortune 2, which can use N-Patches in the Random Mission Generator created maps.


TRUFORM disabled

TRUFORM enabled

As you can see from the above, N-Patches provide a more natural, less angular sloping to the terrain in the game. For a great deal of information on Displacement Mapping I’d suggest you check the Matrox website articles, which contains several Flash demonstrations & other useful information about it.


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