[OpenLayers-Users] Resolution in OpenLayers and Mapserver?

[Stephen Woodbridge]

On 12/29/2013 12:36 PM, saka royban wrote:
> Hi all.
> I'm confused about the concept of resolution in OpenLayers and MapServer and
> the relation between them.
> MapServer has resolution of 72 pixel per inch, as default.
> Resolution of my data in zoom full will be 360 (degrees= whole world) / 512
> (width of image) = 0.703125 degree per pixel.
>
> What's the difference in above 2 numbers conceptually?

The mapserver number is used for scaling the image to output device 
units. It makes a wild assumption that the you screen resolution is 
about 72 pixel per inch. If you were to output the same image to a 
printer you might need to change that to 300 pixel per inch for the printer.

The OpenLayers resolution is the resolution of a pixel to ground units. 
Given a referenced image at N meter or degrees per pixel it defines the 
resolution of the image to the ground units.

If you them want to take an image and map that to an output device like 
a monitor or printer it has to again be scalled by the output resolution.

-Steve W