Re: Threaded drawing
Re: Threaded drawing
- Subject: Re: Threaded drawing
- From: David Duncan <email@hidden>
- Date: Wed, 11 Dec 2013 15:05:35 -0800
On Dec 11, 2013, at 8:05 AM, Jeffrey Oleander <email@hidden> wrote:
> * (The posted snippet from sample code was as clear as mud to me. Why powers of 4 (and -4) instead of 5 when we're talking about 5 levels of detail?
> 1/(2^2) - 2^2 = (1/4) - 4 means "...levelsOfDetail" should be set to 5?!? It needs more words, more context.)
The base level of detail is a zoom level of 2^0 (1 level of detail only allows for a single representation like that). Each additional level of detail is a zoom level half that size smaller (thus a 2nd level if 2^-1x or 1/2x, then 2^-2x or 1/4x, etc). The bias adds to the base level’s exponent, thus a bias of 2 means the base level if 2^2x (4x) zoom instead of 2^0x zoom.
There are no powers of 4, (or 5 or any other except for 2). The level of detail is range of the exponent, not the base.
--
David Duncan
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