Re: PSA: Clock drift and pkgin

On 12/30/2023 3:42 PM, Johnny Billquist wrote:
> On 2023-12-31 00:11, Michael van Elst wrote:
>> Better than 100Hz is possible and still precise. Something around 1000Hz
>> is necessary for human interaction. Modern hardware could easily do 
>> 100kHz.
>
> ? If I remember right, anything less than 200ms is immediate response 
> for a human brain. Which means you can get away with much coarser than 
> even 100Hz.
> And there are certainly lots of examples of older computers with 
> clocks running in the 10s of ms, where human interaction feels perfect.

I'm not sure about visual and auditory sensation, but haptic VR requires 
position updates >= 1000Hz to get texture right.  The timing of two 
impulses that close together may not be felt as two separate events, but 
the frequency of vibrations within the skin when it interacts with a 
surface (even through a tool, such as a stylus) is encoded by the nerve 
endings in the skin itself.  We used to use PHANTOM haptic arms at 
$WORK, driven by an Indigo2. If the control loop operated at less than 
1000Hz---for example, if the Indigo2 was under load--- it introduced 
noticeable differences in the sensation of running the pen over a 
virtual object.  The simulation was much more sensitive to that than it 
was to the timing of the video output, for which anything greater than 
72Hz was wasted.

Take care,

-Konrad