Angus Dorbie (dorbie++at++sgi.com)
Tue, 31 Aug 1999 13:01:30 -0700
It's strange you don't mention texture download rate in the initial list
of limiting factors that IS the crux of the problem here, you do mention
later and I agree with your statement, that's the problem I have been
talking about. You are confusing arguments over geometry bottlenecks in
vertex transformation (which I'm not making) with the texture download
bandwidth limits we should be discussing. Disk is a variable factor, you
can scale disk i/o that's the easy part of the problem if you have the
money to spend and/or the right file system. What is more problematic is
scaling bandwidth into the graphics subsystem.
>
> >It seems more than a little optimistic to say a PC can just do this.
> >Sure it can do something but it can't handle the same class of problem.
> >You have to compare apples with apples, doing otherwise is exactly the
> >kind of loosely defined approach to analysis which has led to problems
> >of programs like CCTT where they realized too late that PC's weren't
> >going to do the job.
>
> To draw this conclusion you're setting a very high bar for the definition
> of a "geospecific database."..
I'm not setting any bar, rather you are deliberately blurring any
differences. I'm trying to draw some distinctions between what a high
end system can do and what a PC can do. To say a system can do
geospecific databases is meaningless. What resolution, what eye speed
what are the bandwidth requirements.
>... This is interesting, I think, for historical
> reasons primarily. Evans & Sutherland used to (and I believe still) do the
> same thing with with the term "real time" against SGI in sales situations.
> They lost market share anyway. I think there may be a lesson there. :-)
Meaningless rhetoric but I'll bite. The lesson is this was marketing FUD
and you shouldn't believe everything you hear from SGI's competition
;-). What E&S used to say is irrelevant to the substance of the
argument. SGI IRIX systems are being replaced in some markets by PC
based systems, that's why solving classes of problem that the PC can't
is important to us, and large geospecific databases is without question
one of those areas. E&S for example claim to do geospecific databases
today but have 1/200th the bandwidth onto the harmony graphics system
that SGI systems do, try and resolve that with claims of large
geospecific paging capability.
>
> On a more serious note, I will say that we have customers generating
> geospecific databases and deploying their applications on Windows boxes
> (some of them sold by SGI) with no complaint from *their* customers. Since
> they are (obviously) not doing so with Performer I think more discussion
> along those lines is probably not appropriate to this forum.
It's appropriate to correct any misconceptions created by another set of
gung ho PC can do this emails. It might be fun for you but it creates
significant problems for customers who need real problems solved. Again
you aren't drawing any distinctions between capabilities, not all
geospecific databases are the same.
Cheers,Angus.
--
"One of the best-known folk theorems of software engineering is that
60% to 75% of conventional software projects are either never
completed or rejected by their intended users. If that range is
anywhere near true (and I've never met a manager of any experience
who disputes it) then more projects than not are being aimed at goals
which are either (a) not realistically attainable, or (b) just plain
wrong."
Eric S. Raymond - The Cathedral and The Bazaar
For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/
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