[ka-Map-users] Same API, but map images instead of tiles

Stephen Woodbridge woodbri at swoodbridge.com
Mon Sep 19 00:09:51 EDT 2005

Delfos, Jacob wrote:
> Steve,
> I can see your point of view, in the sense that when using a few heavy
> raster layers, it's easy to get your server overloaded by tile-requests.
> But what would such a solution have to improve over Chameleon (and
> others), which can be used in an almost no-page-refresh way? Also,

Simplicity for for one and an application that can be deployed with 
either tiles or not depending on the javascript loaded.

> generating and serving out an image as large as a Ka-Map viewport for
> every redraw is quite CPU and Bandwidth expensive... The client-side

I am thinking of generating the image of just the viewed portion of the 
viewport because in many applications the user does not need to pan. So 
if you user usage patterns are goto location, zoom in, zoom out, zoom 
out, pan, zoom in, zoom in, then you are not getting much use of the 
cache and you are loading way more tiles into the viewport than 7 
mapserver image requests. If you done have the tiles already cached on 
the server, you still have to generate them, and bandwidth is higher for 
the tiles because of all the non-viewed tiles that are loaded.

It really makes sense for some application but clearly not for all. If 
it is just a matter of changing the javascript that is loaded, the it 
can be switchable by the user if you want to export the control for that.

Thank you for your comments.

Anyway something to think about,

> caching of tiles helps reduce this issue significantly.
> But I agree that keeping application development separate from
> deployment issues is beneficial.
> Regards,
> Jacob
>>-----Original Message-----
>>From: ka-map-users-bounces at lists.maptools.org 
>>[mailto:ka-map-users-bounces at lists.maptools.org] On Behalf Of 
>>Stephen Woodbridge
>>Sent: 19 September 2005 02:50
>>To: ka-map-users at lists.maptools.org
>>Subject: [ka-Map-users] Same API, but map images instead of tiles
>>Hi Paul,
>>I really like a lot of what is happening with ka-map. It is 
>>great to see 
>>all the community effort going into ka-map.
>>I was wondering what it would take to make it work without 
>>tiles as an 
>>option. The idea would be that most of the code and logic 
>>would be the 
>>same but instead of pulling tiles it would just request a 
>>single image. 
>>On a pan the current image would slide like the current code 
>>and a new 
>>image would be requested and replace the partially obstructed 
>>image from 
>>the pan operation when it is ready. I was thinking that this 
>>part (ie: 
>>tile vs map image rendering) could be broken into two separate models 
>>with a common API and then depending on which was used you would get 
>>different rendering behavior.
>>Why would anyone want this?
>>1) less server requests
>>2) no need for tiles and managing the tiles and disk space
>>3) maintains the rich no page refresh UI
>>4) would allow richer server side image manipulation than 
>>exists today 
>>because of the need to generate generic tiles.
>>5) separates application development from deploy concerns and issues
>>6) would allow ka-map to do something that google can not do
>>Anyway, I thought I would float the idea and see what you had to say. 
>>Also I'm interested if others on the list think there would 
>>be value for 
>>something like this.
>>-Steve W.
>>ka-Map-users mailing list
>>ka-Map-users at lists.maptools.org

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