Making a 4K Fractal Movie with Fractal EXtreme
randomascii.wordpress.com
randomascii.wordpress.com
When I first found XaoS in later years it was amazing, thinking that you could actually zoom in real time (!) and it's nice to see that some programs are still around allowing you to do fractals.
It would be interesting to know which would be the fastest way to calculate them nowadays, if on the CPU or on the GPU (I think in both cases one would have to roll their own high precision math for deep zooms)
(edit) found a post on the Fractal Extreme blog discussing GPU math, it is from 2012 though, I wonder if the intervening 4 years have changed the author's opinion on this.
https://randomascii.wordpress.com/2012/03/28/fractal-and-cry...
I would even go far to say that with current GPU hardware rendering fractals is "solved" in terms of realtime capability. see: https://www.shadertoy.com/results?query=fractal
I think fractals are still awesome despite being pretty simple these days. They are an excellent gateway into doing programing on the GPU. I think they are exactly the type awe inspiring programs that younger students should be shown.
I agree the worse floating point precision of GPUs puts them at a disadvantage but they still do better for massively parallel problems like fractal renders. (http://www.bealto.com/mp-mandelbrot_benchmarks.html)
Most GPUs can, at reduced speed, do double precision, which is 53 bits.
The maximum precision for this zoom movie is 960 bits.
So, unless you write code to compose high-precision math operations out of double-precision math then the GPU cannot even participate. And once you do that you will find that the GPU's speed advantage is mostly or entirely lost.
That means that GPUs are not very good at doing high-precision math. They lose a lot more efficiency implementing high-precision math than CPUs do. And GPUs are also worse at doing parallel calculations that end up following different paths, which inevitably happens when one pixel diverges before another.
My back-of-the-envelope estimates show that GPUs are not worth it for this use-case. I will change my mind when I see a GPU-based deep zoom fractal program.
And you can do add-with-carry manually on the AMD GPU using two instructions: ADDC_UINT to get the carry flag from an addition followed by ADD_PREV to add it.
It would be interesting to see how well a GPU can do compared to a CPU. Doing 64-bit math gives an automatic four-to-one advantage (it takes four 32x32 multiplies to replicate a single 64x64 multiply) so the GPU would be starting out at a disadvantage, plus GPUs run at lower clock rates and have other disadvantages, but perhaps their many many cores would be enough to overcome this.
It would be nice to make rendered animations in this, I don't think that's a feature of the web app. Maybe there's some other way to make animations? Would make a great background for an alien ship flying through an alien cityscape.
Unfortunately they are much harder to calculate.
Typical movie theaters use 4k today, and 2k (very close to 1080p) less than 10 years ago. For their huge screens. Of course the bitrate is very high, "up to 250 Mbit/s" (https://en.wikipedia.org/wiki/Digital_cinema#Technology_and_...)
For small text and fine lines such as used in a close-up computer monitor, 4k+ can be very beneficial. But for video, it's marketing, and a costly waste.
1. http://conversation.which.co.uk/technology/many-blu-rays-no-...
1) Most digital photos are 4K - a 4K TV is ideal for viewing them. 2) Youtube videos 3) This video 4) Other sources of 4K video that are coming online right now.
Sure, you might not get 100% of the benefit of your 4K TV for ten years, but that doesn't mean it's not worthwhile.
In my case I had a terrible old TV, so upgrading was a no-brainer.