What are these lines?

Discussion in '3D Hardware, Software & Output Devices' started by Quitch, May 27, 2009.

  1. Quitch

    Veteran

    Joined:
    Jun 11, 2003
    Messages:
    1,521
    Likes Received:
    4
    Location:
    UK
    I have these odd black lines that I've noticed in newer games

    [​IMG]

    Most noticeable in Far Cry 2 I have spotted them to a lesser extent in STALKER Clear Sky (the dark nature of the game making it much harder to see them). If you turn your head (in-game ;)) then they flicker and shift. I'm unsure whether they're some AF artifact, something to do with the lighting engine, detailed textures or a problem with my ATI HD 4870 X2 card.

    Basically, what are they? In Far Cry 2 I find them incredibly distracting.
     
  2. digitalwanderer

    digitalwanderer Dangerously Mirthful
    Legend

    Joined:
    Feb 19, 2002
    Messages:
    17,274
    Likes Received:
    1,788
    Location:
    Winfield, IN USA
    Dumb question, what black line are you talking about? I'm not seeing it. :???:
     
  3. neliz

    neliz GIGABYTE Man
    Veteran

    Joined:
    Mar 30, 2005
    Messages:
    4,904
    Likes Received:
    23
    Location:
    In the know
    shimmer in the shadows, downgrade to a geforce gtx200 series.
     
  4. Quitch

    Veteran

    Joined:
    Jun 11, 2003
    Messages:
    1,521
    Likes Received:
    4
    Location:
    UK
    The side of the wall I'm staring at, the whole portion not in shadow, lines going off at angles from the divide between the orange and the beige.

    Is this to do with the AF angle "optimisations" of ATI?
     
  5. Humus

    Humus Crazy coder
    Veteran

    Joined:
    Feb 6, 2002
    Messages:
    3,217
    Likes Received:
    77
    Location:
    Stockholm, Sweden
    The picture is too low quality to tell, but given the angle of the incoming lights I think what you're seeing is perspective aliasing of the shadow maps. With a PCF filter it actually gets worse. The shadows look filtered to so I'd say that's most likely the problem. The best way for a developer to deal with this problem is to use a liberal amount of slope depth bias. Still you'll probably find cases like this in all games that use shadow maps.
     
  6. Pete

    Pete Moderate Nuisance
    Moderator Veteran

    Joined:
    Feb 7, 2002
    Messages:
    4,945
    Likes Received:
    350
    Dumber question, are they still there if you disable AF or even all of ATI's optimizations (I forget the name for that)?

    Dumber b/c I can't really see any black lines (on this less-than-great LCD), though I can see some patterns of alternating light and dark bars. The bars/lines are negative slope, nearly vertical in the top (tan/orange) part and closer to 135 degrees in the lower (beige) part. Or are you talking about what seems to be an even fainter pattern (of positive slope) of short (about twice the height of the gun sight) "hatching" centered on the actual color divide on the wall?
     
  7. neliz

    neliz GIGABYTE Man
    Veteran

    Joined:
    Mar 30, 2005
    Messages:
    4,904
    Likes Received:
    23
    Location:
    In the know
    It's there, imagine a very light shadow map on the normal of the darker shadow.

    This is entirely up to the dev and it's use of the shadowmaps. the latest Prince of Persia is a great example of a developer skipping on adequate shadowing.
     
  8. Quitch

    Veteran

    Joined:
    Jun 11, 2003
    Messages:
    1,521
    Likes Received:
    4
    Location:
    UK
    OK, so it's a dev issue, nothing I can do about it then?
     
  9. Bludd

    Bludd Experiencing A Significant Gravitas Shortfall
    Veteran

    Joined:
    Oct 26, 2003
    Messages:
    3,237
    Likes Received:
    806
    Location:
    Funny, It Worked Last Time...
    Maybe supersampling can help?
     
  10. neliz

    neliz GIGABYTE Man
    Veteran

    Joined:
    Mar 30, 2005
    Messages:
    4,904
    Likes Received:
    23
    Location:
    In the know
    not really, it's the resolution of the original shadowmap, it will always look like 64x64 pixels on your screen no matter how much filtering you throw at it.
     
  11. hoom

    Veteran

    Joined:
    Sep 23, 2003
    Messages:
    2,948
    Likes Received:
    497
    They go away if you turn shadows off :wink:
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...