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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>Hi,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>I took some numbers to compare
with.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>Material and methods</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>Polygon layer, rather simple polygons with few
vertises, Feature Count: 117383</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>DEBUG 5 in mapfile</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>WMS client asks for the whole layer</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=371423407-03092010>Mapserver 5.2.1 (CGI) on not so fast Windows
computer</SPAN></FONT><FONT face=Arial color=#0000ff size=2></FONT><BR></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2>Results</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff size=2>First
request: rendering time taken from the log file are between 3.5 and 4.5
seconds</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2>Following request, BBOX is changing but all the polygons are drawn
though: rendering times 1.5 - 2.5 seconds</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2>Conclusions and discussion</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff size=2>At
first one might think that my server is faster. But this test is not
controlled at all because we are not using the same shapefiles and we can't say
so. What we can say that a couple of hundred of thousand polygons can
be drawn faster. </FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2>However, it does not really make sense to render an image this way if it
should be fast. If the screen has 1000 by 1000 pixels it makes a million
pixels together. For 200000 polygons it makes 5 pixels per polygon.
You can simplify your polygon geometries pretty much before anybody can see
the differense. If the polygons are spread evenly nobody can even see
the difference if there are 20000 or 200000 polygons on the
screen.</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2></FONT></SPAN><SPAN class=371423407-03092010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff size=2>We
have one polygon layer with about million polygons and for that I made
two simplified layers which contain only 1 percent and 10 percent of all
the polygons. Those and the original shapefile are put into the same
scale dependent WMS GROUP layer. This group is pretty fast at any
scale. The 1 percent layer is perhaps a bit too sparse but I have been too
lazy to have a try with 2 or 5 percent samples.</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff size=2>-Jukka
Rahkonen-</FONT></SPAN></DIV>
<DIV><SPAN class=371423407-03092010><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV>
<HR tabIndex=-1>
</DIV>
<DIV><FONT face=Tahoma size=2><B>Lähettäjä:</B>
mapserver-users-bounces@lists.osgeo.org
[mailto:mapserver-users-bounces@lists.osgeo.org] <B>Puolesta </B>Chris
Jackson<BR><B>Lähetetty:</B> 2. syyskuuta 2010 23:03<BR><B>Vastaanottaja:</B>
Lime, Steve D (DNR)<BR><B>Kopio:</B>
mapserver-users@lists.osgeo.org<BR><B>Aihe:</B> Re: [mapserver-users] Display
performance<BR></FONT><BR></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV></DIV>Steve<BR><BR>That saves some work, but how long would you expect
one that size to load? I have just realised (admittedly not looked at
the data for a couple of years) that it is actually 170,000 records - takes
about 20 secs to load - sound reasonable?<BR><BR>Chris<BR><BR>
<DIV class=gmail_quote>On 2 September 2010 20:50, Lime, Steve D (DNR) <SPAN
dir=ltr><<A
href="mailto:Steve.Lime@state.mn.us">Steve.Lime@state.mn.us</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">
<DIV lang=EN-US vlink="purple" link="blue">
<DIV>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: rgb(31,73,125)">That’s not that big a
dataset. Probably faster from a local shapefile.</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: rgb(31,73,125)"></SPAN> </P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: rgb(31,73,125)">Steve</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: rgb(31,73,125)"></SPAN> </P>
<DIV
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: rgb(181,196,223) 1pt solid; PADDING-LEFT: 0in; PADDING-BOTTOM: 0in; BORDER-LEFT: medium none; PADDING-TOP: 3pt; BORDER-BOTTOM: medium none">
<P class=MsoNormal><B><SPAN style="FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-SIZE: 10pt"> <A
href="mailto:mapserver-users-bounces@lists.osgeo.org"
target=_blank>mapserver-users-bounces@lists.osgeo.org</A> [mailto:<A
href="mailto:mapserver-users-bounces@lists.osgeo.org"
target=_blank>mapserver-users-bounces@lists.osgeo.org</A>] <B>On Behalf Of
</B>Chris Jackson<BR><B>Sent:</B> Thursday, September 02, 2010 2:29
PM<BR><B>To:</B> <A href="mailto:mapserver-users@lists.osgeo.org"
target=_blank>mapserver-users@lists.osgeo.org</A><BR><B>Subject:</B>
[mapserver-users] Display performance</SPAN></P></DIV>
<DIV>
<DIV></DIV>
<DIV class=h5>
<P class=MsoNormal> </P>
<P class=MsoNormal>Hi<BR><BR>I wondered if anyone knew if displaying a
50,000 polygon dataset would be significantly faster if called from a
database rather than a spatially indexed shapefile, or is it a similar
overhead for both.
<BR>Thanks<BR>Chris</P></DIV></DIV></DIV></DIV></BLOCKQUOTE></DIV><BR></BLOCKQUOTE></BODY></HTML>