<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:10pt"><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; ">Hi,</div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; "><br></div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; ">I would like to have a simple application which delivers wms layers in scales/resolutions which are not the usual OSM/Google messy scales, but rather include 1:1000 000 / 1:500 000 / 1:250 000 / 1:100 000 / 1: 50 0000/ 1:10 000, 1: 5000 and 1:2,500. To make this even more difficult I need to do this in EPSG:25832 the european standard ETRS/ UTM zone 32 projected CRS with units of meters</div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; "><br></div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; ">As far as I have understood, this is fully dependant on
the basemap resolutions. As this is pure mathematical I would like to show what I think I have learnt and wait for comments....</div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; "><br></div><div style="font-family: arial, helvetica, sans-serif; font-size: 10pt; "><br></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2">R = </font><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: small; ">resolution</span><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: small; "> </span></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2">S = </font><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: small; ">scale</span><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; "> as
denominator</span></div><div><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">IPU = </span><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">OpenLayers.INCHES_PER_UNIT[units] = 39.3701 inches in a meter</span></div><div><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">DPI = </span><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">OpenLayers.DOTS_PER_INCH = 25.4 / 0.28 = 90.71428571428571 ( 1 inch = 25.4 mm / standardized pixel size of 0.28x0.28mm)</span></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2"><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; ">this must be set in the application code "OpenLayers.DOTS_PER_INCH = 25.4 / 0.28" = <span class="Apple-style-span"
style="color: rgb(0, 0, 0); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: normal; white-space: normal; ">90.7142 o</span>therwise, the scale factor would be 72 / 90.7143 = 0.7937.</pre></font></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2"><br></font></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2">R= S / IPU * DPI</font></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2"><br></font></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2">using this formular, we are basically working out how many pixels there are in 1 meter of screen, to so find out how many pixels there are in 1000000 meters of screen we use...</font></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="2"><br></font></div><div>[Scale 1:1000 000]</div><div><br></div><div>R = 1000000
/ (39.2701 * <span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">90.71428571428571) </span></div><div><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">R =</span>1000000 <span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; "> / 3562.359071428571260271</span></div><div><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">R = 280.712859077111976006937033</span></div><div><font class="Apple-style-span"><br></font></div><div><font class="Apple-style-span"><br></font></div><div><font class="Apple-style-span">[Scale 1:500000]<br></font></div><div><div>R = 500000 / (39.2701 * <span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">90.71428571428571) </span></div><div><span
class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">R =</span>500000 <span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; "> / 3562.359071428571260271</span></div><div><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">R = 140.356429538555988003468517</span></div><div><br></div><div>...etc for the <span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">1:250 000 / 1:100 000 ...</span></div></div><div><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><br></pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><br></pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; ">What bothers me though, is that every EPSG code with units of meters will have the same resolutions. Is this
correct?</pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><br></pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><br></pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; ">
sources: </pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><a href="http://geowebcache.org/docs/current/concepts/gridsets.html" style="font-family: 'Times New Roman'; line-height: normal; text-align: -webkit-auto; white-space: normal; ">http://geowebcache.org/docs/current/concepts/gridsets.html</a></pre><pre style="color: rgb(34, 34, 34); line-height: 20px; text-align: justify; "><a href="http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation">http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation</a><br></pre></div></div></body></html>