[EMAIL PROTECTED] writes:
> On Tuesday 02 December 2003 02:31, Curtis L. Olson wrote:
>
> > My understanding of systems that impliment these basic ideas is that
> > step 1) is to give up the idea of seamless, non-blurry textures in the
> > distance. Every system I have seen blurs the textures excessively as
> > you go further in the distance ... that also yields a corresponding
> > texture blurry->sharp "popping" effect as you get closer to a new
> > area. And because the system typically has to do this stuff in a low
> > priority thread to keep up rendering rates, you can see by the popping
> > that the detail texture loading often lags and doesn't pop into full
> > detail until you are right over it.
> >
> > Just for fun, sit down and assume 1 meter texture resolution, assume
> > you are flying at 500 kts, and assume something like 20 mile visible
> > radius. Now crunch the math on how much data you have to flow in from
> > your HD per second or per frame, and you will see that it is a *lot*
> > of work.
>
> Couldn't we load the whole data into RAM before?
> 1 GB Ram are cheap today.
1. Threre is a big difference between having texture data loaded into
main RAM vs. having the texture data loaded into your cards video
RAM. (There are probably a few exceptions, the only one I can
think of at the moment is the sgi O2 which has a unified
main/video ram structure.)
2. If my math is working this early, 1GB of ram = 1073741824 bytes.
Now, we need to store 3 bytes per pixel, so 1GB of ram actually
lets us store 1GB/3 = 357913941 pixels of data.
We would need to store a 2d array of RGB values. So
sqrt(357913941) = 18918 x 18918 array of pixels we can store in
1Gb of RAM.
Assuming 1m texture resolution, this gives you a 18.9 x 18.9 km
area you can shove into 1Gb of RAM (assuming all your other
software is taking zero bytes of main RAM.)
That's not much. Assuming even 10km visibility (6.2 miles) means
you could always see off the edge from any place in this area.
Curt.
--
Curtis Olson HumanFIRST Program FlightGear Project
Twin Cities curt 'at' me.umn.edu curt 'at' flightgear.org
Minnesota http://www.flightgear.org/~curt http://www.flightgear.org
_______________________________________________
Flightgear-devel mailing list
[EMAIL PROTECTED]
http://mail.flightgear.org/mailman/listinfo/flightgear-devel
