[OpenLayers-Users] Optimal tile size for tilecache

[Christopher Schmidt]

On Tue, Oct 20, 2009 at 09:43:35AM +0300, Adrian Popa wrote:
> Hello Christopher,
>
> Thanks for your reply.
>
> I am using cgi  mode (because it's been the easiest to setup). How do  
> you recommend I run tilecache? I don't want to precache my whole map  
> because most of the zoom levels (in some areas) don't give much  
> information. I could precache some zoom levels and let the details be  
> rendered on the fly, when needed...

Okay, using CGI is the problem. You can only get about 10 tiles/second
with CGI, compared to hundreds with WSGI, mod_python, etc. So I recommend
setting up mod_python or some other persistant server side process for
serving the tiles, rathere than using CGI, which is much slower. 

> I'm not using metatiles (or at least I think I'm not using them)... I  
> don't really know what metatiles are and what they are supposed to do.  
> Maybe a point to the right documentation would be ok...



>
> The tile loading process goes like this - when I change my zoom the  
> center tiles are loaded pretty quickly (even if they haven't been  
> cached) - in about half a second, but the edges of my image take about  
> ~5 seconds to load. I thought it might be a limitation of my browser -  
> on how many connections it can keep - so I added a lot of connections   
> (20 per server) both on my browser and my web server (20 processes  
> listening). The speed limitation is visible even when the tiles (for  
> that area) have been cached. I thought that by increasing the tile size  
> the browser would make fewer requests and the page would maybe load  
> faster...
>
> Thanks,
> Adrian
>
>
>
> Christopher Schmidt wrote:
>> On Mon, Oct 19, 2009 at 02:30:44PM +0300, Adrian Popa wrote:
>>   
>>> Hello everyone,
>>>
>>> Just wondering - what would be a good tile size to be used for  
>>> tilecache, so that the client will not do a lot of queries to the 
>>> server (seems they take quite a while), and at the same time would 
>>> not load too much information that is not used (areas of tiles which 
>>> are outside the viewable area).
>>>
>>> My web clients use screen resolutions starting from 1200x1024 (and  
>>> usually run the page in full screen).
>>> Right now I have tiles of 256x256 - which seem rather small and take  
>>> some time to load.
>>>     
>>
>> I would try to understand why they take some time to load. Are you using
>> CGI mode? (Don't.) Are you not-precaching as much as you should? Are you
>> using metatiles? Are you not using metatiles? etc.
>>
>> Also, some description of 'some time' -- hundreds of milliseconds, seconds,
>> dozens of seconds -- would probably also be appropriate.
>>
>>   
>>> What tile sizes do you use?
>>>     
>>
>> 256x256. And so does Google Maps, which was doing this before most of us,
>> and probably has a decent idea on how to make things work pretty well.
>>
>> -- Chris
>>
>>   
>>> Thanks,
>>>
>>> Adrian
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users at openlayers.org
>>> http://openlayers.org/mailman/listinfo/users
>>>     
>>
>>   
>
>

-- 
Christopher Schmidt
MetaCarta