Re: [OpenMap Users] Scale, Ceiling and Zoom

From: Don Dietrick <>
Date: Sun, 27 Jun 2004 13:25:45 -0700

Hi Andrew,

On Jun 22, 2004, at 12:05 PM, Andrew Schulak wrote:

> Hi all,
> I just started working with openmap and I was wondering if you all
> could point me in the right direction to find out information on how
> to:
> 1. Set a ceiling of 50,000 feet for a map view.

I think this depends on a bunch of other factors - map size, projection
type. I guess you could figure out the pixel distances for some
relative distances on the map, and use those measurements to figure out
what the scale would have to be to give the appearance of 50,000 ft.

> 2. What exactly the float is when creating a ZoomEvent (i.e. whats the
> best way to zoom in and out)

It's a multiplier to set against the current scale.

> 3. What exactly it means to set the scale of the Proj object.

It's a ratio to provide control over the pixel/projection coordinates
relationship. That's why the answer to #1 is hard, because the scale
doesn't really have units to bounce the height over the map off of.

- Don

Don Dietrick,
BBN Technologies, Cambridge, MA

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Received on Sun Jun 27 2004 - 18:29:33 EDT

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