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

[Lime, Steve D (DNR)]

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
> --
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> Sent from the Mapserver - User mailing list archive at Nabble.com.
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