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hbm
Staff
Posts: 292
Registered: ‎11-05-2015

Re: WMTS tile cache

Do you have any interim news, Craig? Or maybe you've already finished your experiment? :-)

I've remembered one potential pitfall we've encountered earlier in that image manipulation library capabilities might need to be considered. When we implemented tile buffering in the Cache Filler it was found that the standard .NET PNG encoder can't write palette images. As such, even though you wanted 8bit images in your cache, you'd get them transformed into 32bit inflating the size considerably. A similar behavior might exist for JPEG encoded images. A dedicated image codec library could mean additional gains function- and performance-wise.
Occasional Contributor
Posts: 11
Registered: ‎10-19-2015

Re: WMTS tile cache

At this point this is still a work in progress.  Initial testing is look positive so far.  I am on leave this week, but back into it next.

Thank you for you comments re: 8bit and 32bit PNG images, we will check for this.

 

Another question if I may:  we are looking at setting up an AWS processing farm to generate our tile cache in a timely fashion.  We are looking at the possibility of setting up 20x Web instances to generate the tiles for the WMTS.  Each WebMap server will have it's own underlying WMS and source data.  If we use the larger map product and post-process the images, or simply generate the final required map product has yet to be determined.

 

I am looking at running a cache filler service and cache filler manager locally on each of the 20x WebMap servers.

 

My question comes around the target location for the WMTS tile cache.  In your opinion are we better to have each of the 20x WebMap servers writing to their own cache location, and merging the output later, or have all 20x WebMap servers writing to the same (shared) cache location?  Do you see any pitfalls in doing the later - writing to a single shared location from all 20x WebMap servers?

 

Does the tile filler service check the existence of each output file before it processes that individual tile, or does it build a list of missing tiles at start-up and process them all, regardless of if one has been created in-between times?  Does this make sense?

 

Any other suggestions on setting  up a processing farm like this wold be much appreciated.

 

thanks in advance,
Craig

hbm
Staff
Posts: 292
Registered: ‎11-05-2015

Re: WMTS tile cache

 

The Cache Filler service does not check the existence of a file in the destination, it simply grabs the image and saves it to disk after passing through the hashing algorithm. It is the duty of the Cache Filler Manager to check for tile existence first.

 

Actually, I believe the ideal approach would be to designate one cache filling machine and load balance the WMS services. I don't think it is a good idea to write concurrently into a shared network location, even though you could get away with reading from that.

 

Highlighted
Contributor
Posts: 46
Registered: ‎10-13-2015

Re: WMTS tile cache

Hello Craig,

 

Has you progress in your cache.

 

I am sorry, I haven't read this topic previously, really I had many problems with the cache genration and I did severals tools to generate a cache. I have attached a help that I did for them.

 

One of this tools is specally to fill a cahce with the empty tiles. Other move tiles from one to another cache. Let me to know if you are interested in a copy of the programs, in any case it can help you also to do the cache maintenance.

 

Probably you have find out that if you want to cut a tile in several tiles the problems is that you need a power tool or software to cut them because in other case they will be 5 or more times huge and you have many files.

Occasional Contributor
Posts: 15
Registered: ‎12-12-2016

Re: WMTS tile cache

Hi Santiago,

I'm interested in a copy this program, Could you pls send me this program?

my email tangtaiduc@truetech.com.vn

Tks a lot of and hope hear from you soon

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