NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
IKamal
From: Frank Reed
Date: 2008 Sep 22, 21:44 -0400
From: Frank Reed
Date: 2008 Sep 22, 21:44 -0400
First, credit to Paul S. for inventing the clever name "iKamal". Very funny! But alas, if we market one, I can almost guarantee that Apple would claim trademark infringement. They'll probably go after "iAm" one of these days... I was thinking while driving cross-country yesterday about some ways to make a sort of cheap (well, at least not crazy expensive) navigational system using off-the-shelf digital levels or other tricks. Imagine creating a specialty device based on a moderately high-end digital camera ($1000 range) with a built-in digital level and the computing capabilities of an average modern cell phone with a built-in almanac of all objects down to sixth magnitude valid for some period of time. You snap a photo or two at night. With the right settings, you have dozens and dozens of stars in every image. Using standard astrometric algorithms, the device calculates with great accuracy the spot in the heavens it's centered on. A digital camera today can achieve 0.1' accuracy when properly calibrated with relatively little calculational sophistication. Now if we could get the vertical (or level) accurate to some comparable level, we would quickly have a nice navigation system capable of continuous position display, and impressive accuracy, whenever the sky is clear. Using inertial sensors, we could get a good measure of the vertical. But how good? And at what price? And would such a technologically complex system be competitive when GPS is available? Another approach to get a level would be to take photos pointing towards low altitudes (five to ten degrees). With dozens of stars in each image all contributing to a statistical solution, you could get a very good estimate of the position of the horizon by looking at the apparent refractions in the stars' positions (I think it would help to have two cameras in this case, pointing towards roughly perpendicular azimuths). Note that the camera does not need to be aimed at anything in particular. Any old patch of sky would do. Just some things that iPonder... -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---