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ATI Technologies' counter-offensive:
RADEON X1800 (R520),
X1600 (RV530), and X1300 (RV515) Series


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Part 4: Rendering Quality, New Anti-Aliasing and Anisotropic Filtering Modes
(Continuation, DOOM 3)






TABLE OF CONTENTS

  1. Part 1. Theory and architecture
  2. Part 2: Practical examination
  3. Part 3: Game test results (performance)
  4. Part 4: Render quality comparison in games


Settings and conventional signs

  • AA and AF control was done from the game.
  • Drivers were configured by default, except for those modified to analyze the quality in various AA and AF modes.

  • 4x/16x = MSAA 4x, AF 16x
  • 4x+TA/16x = MSAA 4x + Transparency/Adaptive AA, AF 16x
  • 4x+TA/16x+HQ = MSAA 4x + Transparency/Adaptive AA, AF 16x High Quality (HQ AF and Catalyst A.I. Off in R520, Catalyst A.I. Off in R480 and HQ mode in G70)

Doom 3

The next important game to appear was Doom 3. Doom 3 is more unassuming than Far Cry in terms of its support for various features and functions, there is nothing excessive in its engine — only necessary things to create the game. In addition, Doom 3 is the only game in our review that uses API OpenGL.

Remember that ATI has not yet implemented Adaptive AA for OpenGL, so there is no antialiasing for transparent textures in Doom 3 on the RX1800. That's a vexatious issue. However, it's compensated by very few transparent textures in Doom 3.

 
Radeon X1800
GeForce 7800
4x/16x



JPEG (~530 KB) | PNG (~2.6 MB)



JPEG (~530 KB) | PNG (~2.6 MB)
4x+TA/16x



JPEG (~530 KB) | PNG (~2.6 MB)



JPEG (~530 KB) | PNG (~2.6 MB)
4x+TA/16x+HQ



JPEG (~530 KB) | PNG (~2.6 MB)



JPEG (~530 KB) | PNG (~2.6 MB)
 
Radeon X850
4x/16x



JPEG (~530 KB) | PNG (~2.6 MB)
4x+TA/16x
-
4x+TA/16x+HQ



JPEG (~530 KB) | PNG (~2.6 MB)

Not a trace remains of the unanimity in Far Cry. Pay attention how much worse GF7800 filters the grid texture on the floor than both Radeons — the GF7800 can match the RX1800 only in High Quality mode. In our opinion, trilinear filtering in the GF7800 remains "optimized" even in High Quality mode; at least, it obviously of lower quality than that in Radeon cards.

When Catalyst A.I. is disabled, both Radeon cards stop substituting a shader responsible for texture lighting. As a result, lighting changes and performance drops noticeably.

And again we see no special advantages of the new anisotropy algorithm in the R520. None can antialias semitransparent textures in this frame: for some reason, the central grid on the background remains unsmoothed not only on the RX1800, but on the GF7800 as well.

We have witnessed a strange artifact in Doom 3 on the RX1800: HQ anisotropy with active Catalyst A.I. is of lower quality than even the regular anisotropy. That's how it looks: a clearly visible line at the border of the texture and the first MIP level. So you'd better disable Catalyst A.I. to get back the normal HQ anisotropy:

Radeon X1800 HQ AF, AI On Radeon X1800 HQ AF, AI Off






Back: Far Cry | Forward: Half-Life 2

Andrey Vorobiev (anvakams@ixbt.com)
Danil Gridasov (degust@ixbt.com)

October 12, 2005.





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