Comments on: MKMapView and Zoom Levels: A Visual Guide

By: Chris Paynter

Chris Paynter — Thu, 20 Oct 2011 02:16:09 +0000

I have one question. Why do you use:

// clamp large numbers to 28
zoomLevel = MIN(zoomLevel, 28);

when the maximum zoom levels are 20?

By: Chris Paynter

Chris Paynter — Thu, 20 Oct 2011 01:42:37 +0000

This article is great Troy, thanks a lot!

By: iPortable

iPortable — Tue, 12 Oct 2010 12:16:55 +0000

hey want to comment that the zoom level doesn’t start at 0 but from 1 to 21. (you should update the source code). Because if you compare the iPhone map for example on zoom 16 with the map on the google webpage, you will see
simply change “NSInteger zoomExponent = 20 – zoomLevel;” to “…21 – …”

By: Jonathan Addleman

Jonathan Addleman — Thu, 16 Sep 2010 19:18:30 +0000

I’m a little confused why you’re saying that zoom level 20 has a map that’s 536,870,912^2 pixels – shouldn’t it be half that? 256 x 2^20 = 268435456, doesn’t it?

I think this is what hustmobile was asking above.

I can see that you’d have to divide this number in half again to get the ‘mercator offset’ for the code, but it still seems the number is off.

By: Sando

Sando — Thu, 16 Sep 2010 10:24:09 +0000

Excellent! Thank you very much!

By: Kristen Tate

Kristen Tate — Tue, 01 Jun 2010 06:12:22 +0000

If only more than 84 people could read this.

By: Marcus Lange

Marcus Lange — Mon, 31 May 2010 19:20:30 +0000

Haha am I honestly the first comment to your incredible post?!?

By: Larry Metzger

Larry Metzger — Sun, 30 May 2010 08:47:54 +0000

If I had a dollar for each time I came here.. Great writing!

By: Melva Mayo

Melva Mayo — Fri, 28 May 2010 18:35:28 +0000

Very interesting writing! Honest..

By: Tarto

Tarto — Sun, 09 May 2010 10:06:34 +0000

Just one comment : in scaling zoom level, it is written that zooming out doubles the area, isnt it that it double the distances, i.e quadruple the area ?