[OpenLayers-Users] Optimal tile size for tilecache

[Adrian Popa]

Thank you,

I'll try with mod_python.

Another small question - is there any notable speed difference between 
using tilecache (let's say through mod_python) to serve some pre-cached 
tiles and using OpenLayers.Layer.Tilecache to serve the same pre-cached 
tiles?

I'm thinking if I should pre-cache my whole map and use Layer.Tilecache 
or if I can get away by using tilecache.py...

Has anyone done any benchmarks for these methods? If the speed 
difference isn't that great, I wouldn't sacrifice the disk space...

Thank you.

Christopher Schmidt wrote:
> 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
>>>>     
>>>>         
>>>   
>>>       
>>     
>
>   

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