[Mapserver-dev] Rotated Map Rendering

[Steve Lime]

Will people really be moving between rotated and non rotated worlds? The
more
important question is will angles change throughout the course of
interacting with
an app. If so then thats a strong argument for 1. If angles are fixed
then I still like
2, since at least scale would be constant from map to map. I suppose
max flexibilty
suggests not doing that though.

(AUTOEXTENT TRUE/FALSE?)

Steve

>>> Daniel Morissette <dmorissette at dmsolutions.ca> 5/20/2004 10:51:41
AM >>>
Steve Lime wrote:
> 
> Based on your alternatives it seems like 2 mirrors the current
meaning
> of an extent. You get that area plus a bit more. This was going to be
an
> issue regardless of how you define your AOI. What was your original
> plan?
> 

The drawback of #2 is that it is not possible to predict the actual 
scale of the map without complicated calculations, and I fear that some

apps would be broken by this additional adjustment of extents that
would 
be done to accomodate the rotation.

OTOH, if we went with #1, an app could continue to work with the 
"extents before rotation" and completely ignore the fact that there is
a 
rotation, as long as it calls the pixel2georef()/georef2pix() functions

when it deals with user inputs.


> I thought that to deal with the non-square pixel issue in the future
> we'd probably have to set a flag that would alter the meaning of
extent,
> that is, you'd get extactly that extent albeit stretched a bit if
> necessary. I'm not sure how that would play out with rotation.
Probably
> not that big of an issue since only the OGC WMS/WCS specs would
leverage
> that capability very often.
> 

I like the idea of doing this by adding a new parameter (flag) to tell

MapServer that the extents shouldn't be adjusted to the width/height 
aspect ratio. Maybe something like "FORCEEXTENTS TRUE/FALSE" with a 
default to FALSE that maintains the current behavior? (I'm sure we can

find a better nanme for the keyword)

Daniel
-- 
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  Daniel Morissette               dmorissette at dmsolutions.ca 
  DM Solutions Group              http://www.dmsolutions.ca/ 
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