Ron: Very cool! Point C is the intersection of two offset circles with centers at A and B, whose radii is known. I wonder what the exact mathematical formula for this is? Wouldn't it come out as an (x,y) coordinate?
John Carmichael http://www.azstarnet.com/~pappas >All, > >I'm sorry I was only half awake when this thread started so forgive me if >I'm off course. If I had to lay out a large dial (say 100 ft) to a high >degree of accuracy (say .1 of an inch) I would plot all the points not as >x,y co-ordinates. I would plot them all out as the intersection of two >lines from two fixed points. > >To see what I mean pick 2 points that are well established, e.g., point A >where the gnomom meets the dial face, and point B some number of feet due >north (in line with the gnomon base) of point A. Every point on the dial >face is now at the intersection of two tape measures that start at points A >and B. Assuming that the dial face is flat the accuracy would be good as >the tape measures used. For the points that are almost inline with the AB >line, a third point C could be used as one of the points. Point C could be >calculated from points A and B. Of course the computer would have to >calculate all of the points for you. > >As a crude ASCII art: Point X is 30" 1 1/4" from point A, and 22" 3 7/8" >from point B. (A metric tape measure would be a lot handier) > > > B > \ > \ > \ > \ > \ > / X > / C > / > / > / > / > / > / >A >
