From: Adrian Freed <adrian@cnmat.berkeley.edu>
Subject: Re: Automatic projector calibration
Date: October 5, 2014 at 1:08:24 PM MST
The technical notion of lag, does not jive very well with the multiple temporal structures involved in experience.
Using it as a ground truth produces some ugly theories, e.g., http://en.wikipedia.org/wiki/Interaural_time_difference
Notice the frequency dependent hacks added to the theory and vagueness about delay/phase. Also notice that the detailed
anatomical and signal flow analysis says nothing to support the theory other than that there are places the information from each ears meet. I encourage everyone to think this through carefully and build and explore speculatively.
We have been down this hole at CNMAT for pitch detection on guitars. People think you can synthesis sounds that tightly track pitch of a string. You can't. There are no interesting definitions of a low guitar string pitch that would make this possible. One "solution" is to track with a constant lag, i.e. a sort of echo. This conditions and constrains the space considerably. A few artists have done amazing things within these constraints (https://www.youtube.com/watch?v=VYCG5wZ9op8, https://www.youtube.com/watch?v=1X5qDeK3siw) but the apparatus has strong agency and may well interfer with other goals.
On Oct 5, 2014, at 10:44 AM, Evan Montpellier <evan.montpellier@gmail.com> wrote:Pages 36-9 in the thesis deal with tracking moving projection surfaces
at near real-time rates. The short of it is that the max refresh rate
Dr. Lee was able to achieve was 12Hz, noting:
"feedback latency places a substantial constraint on the usage of
alternative patterns that may utilize recent sensor data to improve
tracking performance. Tracking algorithms that require instantaneous or
near instantaneous feedback from sensors are not likely to be executable
in practice."
Perhaps the lag would be be acceptable, though, within some of the
visual movement experiments that already play with time delay.
Evan
On 2014-09-30, 4:47 PM, Byron Lahey wrote:From my perspective, the real value that would come from implementing an
auto-calibration system would be the potential for dynamic projection
surfaces: surfaces that enter or exit a space, expand and contract,
morph into different shapes, etc.
I'm interested but don't have much bandwidth to devote to this.
Byron
On Fri, Sep 26, 2014 at 1:36 PM, Evan Montpellier
<Evan.Montpellier@asu.edu <mailto:Evan.Montpellier@asu.edu>> wrote:
For projects such as the Table of Content/Portals, automatic
projector calibration would save a considerable amount of work and
time. Here's an attractive looking solution from Dr. Johnny Chung
Lee, presently of Microsoft:
http://johnnylee.net/projects/thesis/
Is anyone interested in attempting to implement an analogous system
as part of the Synthesis-TML portal network?