Re: [PanoToolsNG] Re: Logging iPhone4 sensor data and use it with PTGui for leveling Panos (on my wish list)
- Just tried the iPhone 4's app. Its most likely acceptable. Some tests needed with a real plumb.
Sent from my iPhone
On Nov 25, 2010, at 6:47 PM, "panovrx" <panovrx@...> wrote:
> Re miniature accelerometers (MEMS devices) like they use in Iphone etc
> from accelerometer wikipedia article:
> Modern accelerometers are often small micro electro-mechanical systems (MEMS), and are indeed the simplest MEMS devices possible, consisting of little more than a cantilever beam with a proof mass (also known as seismic mass). Damping results from the residual gas sealed in the device. As long as the Q-factor is not too low, damping does not result in a lower sensitivity.
> Under the influence of external accelerations the proof mass deflects from its neutral position. This deflection is measured in an analog or digital manner. Most commonly, the capacitance between a set of fixed beams and a set of beams attached to the proof mass is measured. This method is simple, reliable, and inexpensive. Integrating piezoresistors in the springs to detect spring deformation, and thus deflection, is a good alternative, although a few more process steps are needed during the fabrication sequence. For very high sensitivities quantum tunneling is also used; this requires a dedicated process making it very expensive. Optical measurement has been demonstrated on laboratory scale."
> ie. it is a weight on the end of a strip of some springy material. So you have two cases: when the item you are levelling is steady you can get extremely accurate cheapish digital levelling now == but if you are driving along a bumpy road at speed doing continuous streetview type panoramas with a multicamera array then the response time and damping technology is critical and maybe you have to look at some mechanical levelling/damping system for your rig
> --- In PanoToolsNG@yahoogroups.com, Sacha Griffin <sachagriffin@...> wrote:
> > I imagine you could create a semi mechanical target in unused overlap areas for leveling and color balance and use some pattern recognition on it. Gravity has to be the cheapest and most accurate sensor not counting influences of wind against open chambers.
> > Sent from my iPhone
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