Hi Yves, Mapserver's default resolution is 72 dpi, that should explain your difference.
However I would encourage you to change this in the MAP file if you are running an OGC service, you should use: MAP .. RESOLUTION 90.714 .. instead according to the OGC. Best regards, Bart On 10/22/07, Jacolin Yves <[EMAIL PROTECTED]> wrote: > > Le Friday 19 October 2007 16:24:03 Daniel Morissette, vous avez écrit: > > 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, > > Does the default resolution of a map is 75 dpi? > > The reversion conversion should be : minScale = > (ScaleHint/diag)*resolution > with diag = sqrt(2.0); > resolution in pixel/m -> 2.54 E-02 pixel/inch (equal to dpi?) > > so minScale = (9.97805696859274/sqrt(2.0))*75/2.54*100 > minScale = 20 833 (instead of 20 000) > maxScale = 520 833 (500 000) > > Does this differences are normal? > > Thanks, > > Y. > -- > Yves Jacolin > --- > http://softlibre.gloobe.org >
