Zoom level v m/p

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ananda
Posts: 77
Joined: Thu Jun 25, 2009 8:48 pm

Zoom level v m/p

Post by ananda » Fri May 20, 2011 12:12 am

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,
George

meshman
Posts: 219
Joined: Sun Jan 01, 2006 11:54 pm

Re: Zoom level v m/p

Post by meshman » Fri May 20, 2011 2:54 am

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
Lance

ananda
Posts: 77
Joined: Thu Jun 25, 2009 8:48 pm

Re: Zoom level v m/p

Post by ananda » Fri May 20, 2011 7:33 am

Thanks Lance.
George

rhumbaflappy
Posts: 420
Joined: Sat Oct 16, 2004 10:11 pm

Re: Zoom level v m/p

Post by rhumbaflappy » Fri May 20, 2011 1:46 pm

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
Dick

ananda
Posts: 77
Joined: Thu Jun 25, 2009 8:48 pm

Re: Zoom level v m/p

Post by ananda » Fri May 20, 2011 2:05 pm

Thanks Dick.

I only wished to determine whether it was nearer to 1.2m/p or 0.6m/p
George

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