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Zoom level v m/p
Posted: Fri May 20, 2011 12:12 am
by ananda
Can anyone tell me the correlation between the Google "Zoom level" and metres per pixel?
In particular, what is the m/p value for zoom level 17?
Thanks in anticipation,
Re: Zoom level v m/p
Posted: Fri May 20, 2011 2:54 am
by meshman
Greets George,
Resample generates Zoom=17 from Google (and others) at .59m resolution. In a truly non-scientific manner I made a BGL from one tile from Google at Zoom=17, which is a 256x256 image. I then took the measure tool in SBX and went from TLC to TRC and it showed 119.14m. While the measurement from corner to corner might be off a bit, it still falls around .5m. Thus getting a BGL from Resample at .59m
HTH
Re: Zoom level v m/p
Posted: Fri May 20, 2011 7:33 am
by ananda
Thanks Lance.
Re: Zoom level v m/p
Posted: Fri May 20, 2011 1:46 pm
by rhumbaflappy
You can't get an accurate meters per pixel, as the horizontal resolution will change with latitude. Closer to the poles, the narrower the tiles get.
Dick
Re: Zoom level v m/p
Posted: Fri May 20, 2011 2:05 pm
by ananda
Thanks Dick.
I only wished to determine whether it was nearer to 1.2m/p or 0.6m/p