how does anti-aliasing get done on SGI R.E. and I.R. ?

[megadrive0088]

please tell me how anti-aliasing is acomplished on SGI's early 1990s
Reality Engine/Reality Engine 2 and their mid-late 1990s Infinite Reality.

From what I read a long time ago, both the older RE/RE2 and the more modern IR do some sort of multi-sampling and they do 8x8 samples of it.

correct me if I'm wrong on the AA method used in these SGI's but i'm quite sure that whatever AA method they use, they typically do 8x8 AA
with zero or very little hit in terms of fillrate. (dedicated ASICs for AA)

I wonder when modern PC GPUs are going to have the same quality AND amount of AA that the old Infinite Reality does, or the even older Reality Engines.....

 

[Simon F]

Mega,
Their 1996 Siggraph paper, "InfiniteReality: A Real-Time Graphics System", doesn't seem to say much about AA, so I had to go back to their '93 paper, "RealityEngine Graphics". This seems to say they could use 2 methods.

Judging from the diagram, one appears to be 4x4 supersampling while the other is similar to Schilling's "Area based" method ("A New Simple and efficient antialiasing with sub-pixel masks"). Both have their advantages and disadvantages. (the latter, apparently, has problems at silhouettes).

In all, I would say that their AA seems rather good.

 

[K.I.L.E.R]

4x4 AA is 16AA?

 

[SA]

SGI's Reality Engine initially used a 16x (16 sample points) ordered 4x4 grid. They improved on this by using Schillings area weighting method to improve near horizontal and near vertical edges. However, this method produces artifacts.

SGI's Infinite Reality used an 8x (8 sample points) sparsely sampled 8x8 grid.

 

[ERP]

From what I remember (and I'm sure someone will correct me), of the RE we had for a short time, the quality of the anti aliasing was dictated by the number of rasterboards.
I assume it used supersampling with upto 16 samples (if all 16 rasterboards wither present).

 

[Megadrive1988]

when I asked about AA on SGI's I forgot all about the fact that they are highly scalable and configurable with multipule pipelines and RasterManager boards. the pipelines give you more polygons while the raster boards give you more fillrate, IIRC.