Re: Reverse Engineering

[John Carmichael]

Hi Art.   You wrote: <Keep in mind that the gnomon in the processed picture will be "funny".   Not true! On most stained glass sundials, the glass is opaque or opalized and objects on the outside of the glass not visible through the glass. Since stained glass window gnomons are on the the outside, they are invisible.  So when I fix a stained glass sundial photo it doesn't make the gnomon look "funny" since the gnomon wasn't visible to begin with!   This is true only with stained glass sundials. All other sundials photos that are corrected will show funny looking gnomons.   John     John L. Carmichael Jr. 925 E. Foothills Dr. Tucson Arizona, USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Sundial Sculptures Website: http://www.sundialsculptures.com Stained Glass Sundials Website: http://advanceassociates.com/Sundials/Stained_Glass ----- Original Message ----- From: [EMAIL PROTECTED] To: sundial@rrz.uni-koeln.de Sent: Wednesday, February 11, 2004 7:37 AM Subject: Re: Reverse Engineering In einer eMail vom 11.2.2004 15:21:05 Westeuropäische Normalzeit schreibt [EMAIL PROTECTED]: I used Photoshop's image distortion, skew and perspective features extensively to "fix" many of the photos on the site so that it looks like the camera was centered in front of the center of the dial faces. Keep in mind that the gnomon in the processed picture will be "funny".  If you only use the hour lines to calculate the latitude you will be OK.  I think it should also be possible to determine the latitude from the gnomon without reference to the hour lines.  You will still need to use clues about the vertical and horizontal, and you will need both the free edge of the gnomon and the line where it intersects the plate, plus the assumption that it is perpendicular to the plate. --Art Carlson