Jacolin Yves wrote:
Hi list,
After a GetCapabilities resquest on a mapserver server, I find this line
inside my xml file:
<ScaleHint min="9.97805696859274" max="249.451424214819" />
In my mapfile, I defined min et max scale values with:
MINSCALE 20000
MAXSCALE 500000
How can I convert the scaleHint value to the mapfile value? In other words,
what does scaleHint values means?
WMS defines the scalehint values as the ground distance in meters of the
southwest to northeast diagonal of the central pixel of a map. ScaleHint
values are the min and max recommended values of that diagonal. (See WMS
1.1.0 sect. 7.1.5.4)
It is calculated in msWMSPrintScaleHint() in MapServer's mapwms.c:
diag = sqrt(2.0);
if (minscaledenom > 0)
scalehintmin =
diag*(minscaledenom/resolution)/msInchesPerUnit(MS_METERS,0);
if (maxscaledenom > 0)
scalehintmax =
diag*(maxscaledenom/resolution)/msInchesPerUnit(MS_METERS,0);
The use of inchesPerUnit conversion is because resolution is in pixels
per inch, and we need the result in meters.
I'll leave it as an exercise to you to figure out the reverse conversion
(scalehint -> scaledenom). ;)
Daniel
--
Daniel Morissette
http://www.mapgears.com/
