[OpenLayers-Users] Optimal tile size for tilecache

[Adrian Popa]

Thank you for your explanations.

Regards,
Adrian

Christopher Schmidt wrote:
> On Tue, Oct 20, 2009 at 04:25:01PM +0300, Adrian Popa wrote:
>   
>> 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?
>>     
>
> Some. The key difference is that serving pre-cache tiles can be done on much
> lower resource webservers. mod_python can get bulky, but Layer.TC can
> read from a minimal webserver like lighthttpd, etc. that tileCache itself
> wouldn't want to be run on.
>
>   
>> 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...
>>     
>
> You probably don't need to pre-cache your whole map. You will see a 
> tremendous speedup switching to mod_python.
>
>   
>> Has anyone done any benchmarks for these methods? If the speed  
>> difference isn't that great, I wouldn't sacrifice the disk space...
>>     
>
> The speed difference is not quite nonexistent, but is negligable for
> anything but the most demanding use case (hundreds of users, etc.)
>
>   
>> 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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