NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Dip-meter again
From: Bruce J. Pennino
Date: 2013 Apr 10, 16:37 -0400
From: Bruce J. Pennino
Date: 2013 Apr 10, 16:37 -0400
Bruce
Hello Richard and All:
Thinking about this a bit more. I was going to
measure starting at 1,000 ft between two points. Measure on the
ground to 800, 600, 400, 200 and 100 ft. I assume that % error will increase at
shorter distances. Then compare my true lengths to the google scaled
lengths. I seldom scale anything less than 200 ft or so. I'll start
looking for a good place where there are numerous overhead visible objects at
somewhat regular intervals.
Bruce
----- Original Message -----From: Richard B. LangleySent: Wednesday, April 10, 2013 1:35 PMSubject: [NavList] Re: Dip-meter again
Depending on how you use it, Google Earth images might not give results better than 1 metre but that might be sufficient. I used a Google Earth image to measure the distance between (the centres of) two GNSS antennas on the roof of Head Hall. The GNSS-determined baseline length is 19.010 metres. An initial determination using the Google Earth image gave 19.49 metres. Zooming OUT and remeasuring gave 19.18 metres. -- Richard Langley On 2013-04-10, at 2:10 PM, Bruce J. Pennino wrote: > Absolutely brilliant and simple! Why didn't I think of that? I scale distances frequently from online maps/charts. Just yesterday I had to do a quicky estimate for an elevated "high line" of bridges and walkways. I measured 200 ft with a tape, and the guesstimated the length would be 1200 ft. I'm going to go back to the site with my tape. Measure it more accurately and compare it to Google earth. Your idea also offers a simple way to check other measurements. I like it. > > Bruce > ---------------------------------------------------------------- > NavList message boards and member settings: www.fer3.com/NavList > Members may optionally receive posts by email. > To cancel email delivery, send a message to NoMail[at]fer3.com > ---------------------------------------------------------------- > > : http://fer3.com/arc/m2.aspx?i=123502 > ----------------------------------------------------------------------------- | Richard B. Langley E-mail: lang---ca | | Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ | | Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 | | University of New Brunswick Fax: +1 506 453-4943 | | Fredericton, N.B., Canada E3B 5A3 | | Fredericton? Where's that? See: http://www.fredericton.ca/ | -----------------------------------------------------------------------------: http://fer3.com/arc/m2.aspx?i=123503