Dear Roger, Damia and all, Instead of fiddling with the display settings of the monitor, I use the Pen Tool of my image processing program, Paint Shop Pro, to measure wall declination. I guess other programs have a similar tool.
When drawing a straight line over a sharp picture element parallel to the wall (roof ridge, roof edge, street side,...), the status bar shows the direction in 1 decimal. I assume that it is the arc-tangent of the x and y displacements in pixels. With a good quality of the satellite image, the accuracy is about 0.5°. An assumption for this method is, of course, that the x and y pixel distances of the satellite image are equal. Best regards, Frans Maes Roger Bailey wrote: > I routinely use Google Earth to determine wall declination. Depending on the > quality of the picture, resolution to within one degree can be achieved. The > default orientation for Google Earth is straight north up for the center of > the starting image. I have a flat screen with vertical sides and horizontal > top and bottom that are useful reference lines. Check your screen settings. > On most displays these days, x and y are not equal. I had to choose a > display settings to match the dimensions of the monitor. > > There are examples of wall declination using Google Earth in some of the > presentations on my website. "Timelines" #5 may be the most useful. > > Regards, > Roger Bailey > Walking Shadow Designs > www.walkingshadow.info > > -------------------------------------------------- > From: "Damia Soler Estrela" <l...@damia.net> > Sent: Monday, June 08, 2009 5:53 AM > To: "Sundial List" <sundial@uni-koeln.de> > Subject: Wall declination using google earth > >> Hello: >> >> You are talking about physical declinometers in order to know the >> wall declinations, I think that is the most acurrate method, but I have >> been using google earth, you can see the wall of the buildind or the >> aligned street, and could calculate the declination from North? (You >> have a rule to measure the x and y axis, or read the coordinates). >> >> What do you think about the accuracy of this method? >> Do you have any information about the accuraccy of google earth in >> order to measure declination? >> >> >> Best regards >> Damià >> --------------------------------------------------- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> > > > >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 8.5.339 / Virus Database: 270.12.55/2160 - Release Date: 06/07/09 >> 05:53:00 >> > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
