[mapserver-users] Re: WMS and tiles cutting off

Mon May 3 20:01:44 EDT 2010

Ok well, got a big update here.  I was able to switch it back to a 256x256
WMS tiled layer.  My problem was that the symbols were being clipped,
however, by using the openlayers "gutter" property, I was able to fix this
problem. I am using a 1.0 ratio, and the tiles seem to be loading in much
faster, and with a gutter value of 32 the clipping is completely gone.

For those that don't know, the gutter parameter is one that is a property of
the OpenLayers.Layer class.  This is the description:

{Integer} Determines the width (in pixels) of the gutter around image tiles
to ignore.  By setting this property to a non-zero value, images will be
requested that are wider and taller than the tile size by a value of 2 x
gutter.  This allows artifacts of rendering at tile edges to be ignored.
Set a gutter value that is equal to half the size of the widest symbol that
needs to be displayed.  Defaults to zero.  Non-tiled layers always have zero
gutter.

I am going to see if my client is satisfied with the speed, and I will
continue trying different things to optimize, obviously if anyone has any
suggestions they are welcome =).  Thanks a lot for the help so far everyone.

-Adam

On Mon, May 3, 2010 at 7:52 PM, Lime, Steve D (DNR)
<Steve.Lime at state.mn.us>wrote:

> How big are (and how many) the images requested by OL? You've been through
> so many changes I'm not sure exactly what configuration you're using:
>
>  - tiled vs. untiled?
>  - layer ratio setting?
>
> Steve
> ________________________________________
> From: mapserver-users-bounces at lists.osgeo.org [
> mapserver-users-bounces at lists.osgeo.org] On Behalf Of Adam Eskreis [
> aeskreis at gmail.com]
> Sent: Monday, May 03, 2010 6:23 PM
> To: Rahkonen Jukka
> Cc: mapserver-users at lists.osgeo.org
> Subject: Re: [mapserver-users] Re: WMS and tiles cutting off
>
> Thank you for the advice Jukka.  I tried just running shp2img.  The results
> are almost instant.  I also tried using my client with the symbols turned
> off, and the result was about half the load time.  So I guess from this we
> can assume that there is a certain amount of overhead that openlayers is
> giving me, as well the symbols are causing some overhead.  The only thing
> is, what to do?  I can't sacrifice any more quality on my symbols (whcih are
> 8 bit png images) and openlayers as far as I know is the best client out
> there.
>
> Things are starting to look grim
>
> On Mon, May 3, 2010 at 2:44 PM, Rahkonen Jukka <Jukka.Rahkonen at mmmtike.fi
> <mailto:Jukka.Rahkonen at mmmtike.fi>> wrote:
> Hi,
>
> If the query is optimized then try to find out real bottle neck. I believe
> that first step would be to throw away your client and test with shp2img and
> by having DEBUG 5 with all your layers. If you believe that the reason is
> due to symbols, then have a try by commenting out all the symbols you will
> soon know it for sure. I have not played with symbols myself but I can
> imagine that some sort of symbols are faster to render than others
> (truetype/pixmap/inline).
>
> -Jukka Rahkonen-
>
>
>
> Adam Eskreis wrote:
>
> > Thank you for the response David.
>
> > I have optimized the query all I can.  I have optimized the query to the
> point that even with all categories selected, the query has a run time of
> 52
> ms.  I can only assume that the issue lies with the generation of the
> images.  I will try to run it without the "IN" part of the query, but I
> can't imagine that it'st he problem.  I think the problem is that there are
> a large number of symbols that need to be generated, and it's taking
> mapserver a long time to load them in.  Also, yes I have indexes on all
> columns that I am calling in, and yes, they are all using the same SRS.  I
> am still trying a few more things, but I don't think it's the database
> query
> that's causing the problem.
>
>
> > On Fri, Apr 30, 2010 at 9:37 AM, Fawcett, David (MPCA) <
> David.Fawcett at state.mn.us<mailto:David.Fawcett at state.mn.us>> wrote:
>
> >>  Adam,
> >
> >
> >
> >> It sounds like you have boiled the issue down to too much of a time lag
> > between the time the query is executed and the image appears in the
> client.
> >
> >
> >
> >
> >> Is it taking a long time for MapServer to draw the image, or is it the
> > delivery of the image to the requesting machine and subsequent placement
> in
> > the client?
> >
> >
> >
> >> If it is taking MapServer a long time, maybe there are some more data
> > optimizations that you can do.  Is there a better way to structure your
> > data, can you do any pre-processing?  Is it all in the same SRS, got
> > attribute and spatial indexes?  I have used the SQL IN for some apps with
> > reasonable performance, but in the last 6 months or so, there were some
> > posts on this list comparing the use of IN to a layer (or class?) filter.
> > The latter solution was significantly faster.
> >
> >
> >
> >> If it is taking a long time to get to the client, then that is likely an
> > infrastructure issue on either end.
> >
> >
> >
> >> If you want some more help digging in more deeply, post some more stats
> and
> > mapfile snippets.
> >
> >
> >
> >> David.
> >
> >
> >
> > *From:* mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org> [mailto:
> > mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org>] *On Behalf Of *Adam Eskreis
> > *Sent:* Thursday, April 29, 2010 4:24 PM
> > *To:* Lime, Steve D (DNR)
> > *Cc:* mapserver-users at lists.osgeo.org<mailto:
> mapserver-users at lists.osgeo.org>
> >
> > *Subject:* Re: [mapserver-users] Re: WMS and tiles cutting off
> >
> >
> >
> > I tried doing ratio:1 unfortunately it doesn't seem like enough of a
> > performance increase.  Separate layers for each category is an option,
> > however, there are over a hundred categories, and any combination of
> > categories can be on at any given time, so this could prove to have
> > performance issues of it's own.  However, I thank you guys Steve and
> Kaipi
> > for your advice.  I think I am just going to go back to my old method,
> which
> > was using php mapscript to generate the tiles, then each time the user
> > selected new categories, purge the cache and remake the mapfile.  It's
> not
> > the ideal solution but it seems to be the only one.
> >
> > Thanks again,
> >
> > -Adam
> >
> > On Thu, Apr 29, 2010 at 3:50 PM, Lime, Steve D (DNR) <
> > Steve.Lime at state.mn.us<mailto:Steve.Lime at state.mn.us>> wrote:
> >
> > Note that by default I believe openlayers will request an image that is
> > *much* larger than what is visible. Setting the layers (OL) ratio:1 makes
> it
> > the same size as the view port and that can speed up rendering
> considerably.
> >
> > Alternatively you could create a separate set of tiles for each category
> I
> > suppose and switch OL layers as necessary...
> >
> >
> > Steve
> >
> > ________________________________________
> > From: mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org> [
> > mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org>] On Behalf Of Adam Eskreis [
> > aeskreis at gmail.com<mailto:aeskreis at gmail.com>]
> >
> > Sent: Thursday, April 29, 2010 2:25 PM
> >
> > To: mapserver-users at lists.osgeo.org<mailto:
> mapserver-users at lists.osgeo.org>
> > Subject: Re: [mapserver-users] Re: WMS and tiles cutting off
> >
> > Ok, I just gave an untiled layer a try, unfortunately though, due to the
> > large amount of symbols being displayed on the screen, there is about a 2
> > second delay every time the map is panned.  My client will most certainly
> > find this unacceptable.  I have tried using smaller images, but I cannot
> > sacrifice any more quality.  I believe my database query to be as
> optimized
> > as it can be (has about 50 ms runtime, I honestly don't think I can get
> it
> > any lower than that).
> >
> > If these are the only options, is there something else besides WMS that
> you
> > all would recommend using to solve this issue?
> >
> > Thanks,
> > -Adam
> >
> > On Thu, Apr 29, 2010 at 2:54 PM, Lime, Steve D (DNR) <
> > Steve.Lime at state.mn.us<mailto:Steve.Lime at state.mn.us><mailto:
> Steve.Lime at state.mn.us<mailto:Steve.Lime at state.mn.us>>> wrote:
> > So use two layers. One for the background, use tilecache for that. Then
> use
> > an untiled wms/mapserver layer for the overlayed points. - Steve
> > ________________________________________
> >
> > From: mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org><mailto:
> > mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org>> [
> > mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org><mailto:
> > mapserver-users-bounces at lists.osgeo.org<mailto:
> mapserver-users-bounces at lists.osgeo.org>>] On Behalf Of Adam Eskreis [
> > aeskreis at gmail.com<mailto:aeskreis at gmail.com><mailto:aeskreis at gmail.com
> <mailto:aeskreis at gmail.com>>]
> >
> > Sent: Thursday, April 29, 2010 1:24 PM
> >
> > To: mapserver-users at lists.osgeo.org<mailto:
> mapserver-users at lists.osgeo.org><mailto:mapserver-users at lists.osgeo.org
> <mailto:mapserver-users at lists.osgeo.org>
> > >
> >
> > Subject: Re: [mapserver-users] Re: WMS and tiles cutting off
> >
> > I have thought about using tilecache with metatiling, however there is a
> > caveat about this map that i forgot to mention in my main post, and it
> has
> > to do with that "categories" parameter.  Basically, each point/symbol on
> the
> > map has an associated category in the database backend.  I am using
> > mapserver/WMS parameters to change the categories which are called.  Each
> > time the user selects a category, only the points in that category are
> > shown.  My query in the mapfile looks something like thi:
> >
> > SELECT point_geom,gid,symbol,angle FROM mapdata WHERE category
> > IN(%CATEGORIES%)";
> >
> > And each time the user changes the categories, I use openlayers to merge
> > new parameters, and input the new category values that should be used.
>  Is
> > tilecache still useable if I have a system like this set up?
> >
> > Thanks,
> > -Adam
> >
> >   On Thu, Apr 29, 2010 at 6:14 AM, kaipi <mapcollect at gmx.net<mailto:
> mapcollect at gmx.net><mailto:
> > mapcollect at gmx.net<mailto:mapcollect at gmx.net>><mailto:mapcollect at gmx.net
> <mailto:mapcollect at gmx.net><mailto:mapcollect at gmx.net<mailto:
> mapcollect at gmx.net>>>>
> > wrote:
> >
> > Hi,
> >
> > you can use  http://tilecache.org/ Tilecache   with the option
> metatiling
> > enabled. With metatiling enabled Tilecache will fetch larger tiles (eg.
> > 4096x4096) from Mapserver and will cut them into smaller tiles (eg.
> > 256x256). It will also increase performance because Mapserver does not
> need
> > to render tiles when they are already in cache.
> >
> > kaipi
> > --
> > View this message in context:
> >
> http://osgeo-org.1803224.n2.nabble.com/WMS-and-tiles-cutting-off-tp4978418p4979280.html
> > Sent from the Mapserver - User mailing list archive at Nabble.com.
> > _______________________________________________
> > mapserver-users mailing list
> >
> > mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org
> ><mailto:mapserver-users at lists.osgeo.org<mailto:
> mapserver-users at lists.osgeo.org>
> > ><mailto:mapserver-users at lists.osgeo.org<mailto:
> mapserver-users at lists.osgeo.org><mailto:
> > mapserver-users at lists.osgeo.org<mailto:mapserver-users at lists.osgeo.org
> >>>
> >
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >
> >
> >
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/mapserver-users/attachments/20100503/a3a94cce/attachment-0001.html