NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: On the integration of location and data
From: George Huxtable
Date: 2009 Nov 3, 10:13 -0000
From: George Huxtable
Date: 2009 Nov 3, 10:13 -0000
Frank Reed reminds us of an earlier thread "Learn the stars, by phone", that he started on 13 May this year. I am surprised that he does so. New readers would be well-advised to follow that thread, to see where it led to. He writes- "Yes. Augmented reality! This is the cool development in smartphone technology I was talking about last spring that we could leverage very easily for celestial navigation education (here's a link to a message of mine in that earlier thread: http://fer3.com/arc/m2.aspx?i=108258). " =========================== It turned out that Frank's claims for the precision of such devices, which relied on the local magnetic field, were based on early statements by Celestron of the pointing-precision of their "Skyscout" viewer. Frank quoted a pointing precision of half a degree, which was then challenged as implausible. And by that time, Celestron's claimed precision had been well watered-down to 3 degrees, which corresponds to an area of sky which would contain 36 times as many stars as before. That made a lot of difference. If you pointed it at Jupiter, it might identify it as Jupiter, but might just as well identify it as one of several other-bodies, within that 3-degree-radius circle. As it kept many thousands of stars in its memory-locker, that would be all too likely. He now invites us to look again at his earlier posting, without drawing attention to any such defects. This time, he adds- "The article doesn't mention that this technology depends not just on location data, but also on orientation data which generally implies a built-in magnetic compass. There's a way around this in major cities if you use some sophisticated processing (which can occur server-side) to take the image, the GPS (or wifi) location data and then figure out direction based on the buildings seen and maybe even using shadows if it's daytime. That combined with the simple inertial sensors in many phones would yield orientation without a magnetic compass." That notion seems even more implausible than the previous one, for viewers of the night sky. He ends his gee-whizzery with - "And now we just need someone to write some applications that feature the celestial navigation data prominently." It seems to me, we need someone to invent a way of getting some pointing-precision first, before we concern ourselves with such applications. I don't say it's impossible. Maybe, some day, ring-lasers will be made that can go into a pocket. But not yet; not with sensors that rely on the local magnetic field. George. contact George Huxtable, at george@hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---