<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; "><span>Hi,</span></div><div style="font-family: arial, helvetica, sans-serif; "><span><br></span></div><div style="font-family: arial, helvetica, sans-serif; "><span>Thanks.</span></div><div style="font-family: arial, helvetica, sans-serif; "><span><br></span></div><div style="font-family: arial, helvetica, sans-serif; "><span><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: Arial; font-size: 13px; ">"The differences between the different projections is, that the meter doesn't describe the real length." ...ok I think I see...you mean that google distorted the projection so it fits nicely in a square whereas the others are "real" projected coordinate systems?</span><br></span></div><div style="font-family: arial, helvetica, sans-serif; "><span><span
class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: Arial; font-size: 13px; "><br></span></span></div><div><font class="Apple-style-span" color="#0000ff" face="Arial">But what I was really asking is that why have I seen so many different resolutions for various maps.</font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial"><br></font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial">cheers,</font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial"><br></font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial">Rob</font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial"><br></font></div><div><font class="Apple-style-span" color="#0000ff" face="Arial">.</font></div><div style="font-family: arial, helvetica, sans-serif; "><br></div> <div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; "> <div style="font-size: 12pt;
font-family: 'times new roman', 'new york', times, serif; "> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">Von:</span></b> Arnd Wippermann <arnd.wippermann@web.de><br> <b><span style="font-weight: bold;">An:</span></b> 'Robert Buckley' <robertdbuckley@yahoo.com> <br><b><span style="font-weight: bold;">Cc:</span></b> users@openlayers.org <br> <b><span style="font-weight: bold;">Gesendet:</span></b> 19:01 Dienstag, 6.Dezember 2011<br> <b><span style="font-weight: bold;">Betreff:</span></b> AW: [OpenLayers-Users] Creating an application with pre-defined mapscales/resolutions<br> </font> <br><div id="yiv1492762737">
<div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">Hi,</font></span></div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">it should be correct. 1 meter is always 1 meter. The
differences between the different projections is, that the meter doesn't
describe the real length.</font></span></div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">EPSG:25832 is a projection, where a meter on map is a meter in
reality.</font></span></div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">For i.e. EPSG:900913 (Google Projection) it's
not.</font></span></div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">Distance Düsseldorf - Hannover </font></span></div>
<div> </div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">EPSG:25832 : 240.9911275436498<br>EPSG:900913 :
389.3661105393922<br></font></span></div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv1492762737484344917-06122011"><font color="#0000ff" size="2" face="Arial">Arnd</font></span></div><br>
<div dir="ltr" lang="de" class="yiv1492762737OutlookMessageHeader" align="left">
<hr tabindex="-1">
<font size="2" face="Tahoma"><b>Von:</b> openlayers-users-bounces@lists.osgeo.org
[mailto:openlayers-users-bounces@lists.osgeo.org] <b>Im Auftrag von </b>Robert
Buckley<br><b>Gesendet:</b> Dienstag, 6. Dezember 2011 08:48<br><b>An:</b>
users@openlayers.org<br><b>Betreff:</b> [OpenLayers-Users] Creating an
application with pre-defined mapscales/resolutions<br></font><br></div>
<div style="background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-size: 10pt; font-family: arial, helvetica, sans-serif; ">
<div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; ">Hi,</div>
<div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; "><br></div>
<div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; ">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-size: 10pt; font-family: arial, helvetica, sans-serif; "><br></div>
<div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; ">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-size: 10pt; font-family: arial, helvetica, sans-serif; "><br></div>
<div style="font-size: 10pt; font-family: arial, helvetica, sans-serif; "><br></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif">R
= </font><span style="font-size: small; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">resolution</span><span style="font-size: small; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span"> </span></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif">S
= </font><span style="font-size: small; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">scale</span><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span"> as denominator</span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">IPU = </span><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">OpenLayers.INCHES_PER_UNIT[units] = 39.3701 inches in a
meter</span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">DPI = </span><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">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="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif"><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);">this must be set in the application code "OpenLayers.DOTS_PER_INCH = 25.4 / 0.28" = <span style="line-height: normal; white-space: normal; color: rgb(0, 0, 0); font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">90.7142 o</span>therwise, the scale factor would be 72 / 90.7143 = 0.7937.</pre></font></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif"><br></font></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif">R=
S / IPU * DPI</font></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif"><br></font></div>
<div><font class="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif">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="yiv1492762737Apple-style-span" size="2" face="arial, helvetica, sans-serif"><br></font></div>
<div>[Scale 1:1000 000]</div>
<div><br></div>
<div>R = 1000000 / (39.2701 * <span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">90.71428571428571) </span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">R =</span>1000000 <span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span"> / 3562.359071428571260271</span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">R = 280.712859077111976006937033</span></div>
<div><font class="yiv1492762737Apple-style-span"><br></font></div>
<div><font class="yiv1492762737Apple-style-span"><br></font></div>
<div><font class="yiv1492762737Apple-style-span">[Scale 1:500000]<br></font></div>
<div>
<div>R = 500000 / (39.2701 * <span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">90.71428571428571) </span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">R =</span>500000 <span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span"> / 3562.359071428571260271</span></div>
<div><span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">R = 140.356429538555988003468517</span></div>
<div><br></div>
<div>...etc for the <span style="font-size: 13px; font-family: arial, helvetica, sans-serif; " class="yiv1492762737Apple-style-span">1:250 000 / 1:100 000 ...</span></div></div>
<div><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><br></pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><br></pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);">What bothers me though, is that every EPSG code with units of meters will have the same resolutions. Is this
correct?</pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><br></pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><br></pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);">sources: </pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><a rel="nofollow" style="line-height: normal; white-space: normal; font-family: 'Times New Roman'; " target="_blank" href="http://geowebcache.org/docs/current/concepts/gridsets.html">http://geowebcache.org/docs/current/concepts/gridsets.html</a></pre><pre style="TEXT-ALIGN:justify;LINE-HEIGHT:20px;COLOR:rgb(34,34,34);"><a rel="nofollow" target="_blank" href="http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation">http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation</a><br></pre></div></div></div>
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