“Great frame rate” report…and questions

[Jimko]

Griphos wrote " I think FPS around 30, that STAYS around 30, of course, is plenty good, and certainly any higher than 60 would seem to me to be chasing rapidly diminishing, if not imaginary, returns. "
I'd like to offer a couple of comments:
1) I work designing medical imaging systems and can state from personal experience that there are easily perceptable visible difference between 37.5 Hz and 75 Hz image updates for simple tasks such as scrolling a display window horizontally . At 37.5Hz, most observers can easily perceive a jerkiness to the updates. At 75 Hz, scrolling smoothness is much improved. Most monitors now run at fairly high refresh rates to reduce eye fatigue. The 60 Hz flicker from AC lighting is also readily perceptible by many people, even if only at a reduced level.
There has been a lot of work done on the so called "flicker fusion frequency" (http://en.wikipedia.org/wiki/Flicker_fusion_threshold). When I took a graduate course in human vision in the early 90s, we were quoted figures of 15-30 Hz for the flicker fusion frequency (the rate at which a flickering light begins to be perceived as a steady source). However, the human visual system is much more complex than the simple models sometimes used to describe it and a single number doesn't come close to capturing the true behaviour.
2) One of the other important factors for visual feedback in control systems is the control loop latency -- that it is, the time interval between when the user makes a control change and the time they see the effects of that change on the monitor. For typical gaming scenarios, there is probably at least a one or two frame lag in the signal formation chain between the time the system starts building up the image data for a frame and the time frame is finished writing to the screen. If you are running at a 20 Hz frame rate, then that delay can be 50-100ms. If you are running at a 75 Hz frame rate (and the signal processing engine is keeping up), then the control latency can be reduced to 13-26ms. For most people, particually hardcore gamers, this should result in improved control "feel". If you are watching a movie, on the other hand,latency is irrelevant.
Alas, my old computer can only reach frame rates of 15-25 Hz in a BHAH furball (at reduced graphics settings, v-sync off), so stutter and latencies are both issues for me. I still love flying this sim, however.
Cheers and happy flying!!

A very interesting commentary, Mudman!

These are the kinds of things I speculated about when I referred to the possibility of "improve game functionality" beyond simple graphics quality with higher frame rates. And by that I don't mean that I am at all aware of them, just that I wondered if there are other reasons that the game may run more efficiently with consequent slight improvements to the "human experience".

[Queeg]

2) One of the other important factors for visual feedback in control systems is the control loop latency -- that it is, the time interval between when the user makes a control change and the time they see the effects of that change on the monitor. For typical gaming scenarios, there is probably at least a one or two frame lag in the signal formation chain between the time the system starts building up the image data for a frame and the time frame is finished writing to the screen. If you are running at a 20 Hz frame rate, then that delay can be 50-100ms. If you are running at a 75 Hz frame rate (and the signal processing engine is keeping up), then the control latency can be reduced to 13-26ms. For most people, particually hardcore gamers, this should result in improved control "feel". If you are watching a movie, on the other hand,latency is irrelevant.
Alas, my old computer can only reach frame rates of 15-25 Hz in a BHAH furball (at reduced graphics settings, v-sync off), so stutter and latencies are both issues for me. I still love flying this sim, however.
Cheers and happy flying!!

On my rig anyway, my aircraft seems much more responsive when my framerate exceeds 30 FPS. Less than that, and I feel a bit like I'm flying in water. So, to me anyway, FPS is more than just how the game looks -- it's also how my crate flies.