[mapguide-internals] Dynamic tile rendering proposal

[Kenneth Skovhede, GEOGRAF A/S]

As I understand meta tiling, it works by creating a larger image than 
the one requested (smaller),
in anticipation of requests to similar/adjacent (smaller) images.

In a sense, that is what I want, but I would request the larger image, 
and retrieve the sub-tiles.
Unlike meta-tiling, the purpose of this feature is not to create extra 
data in advance,
but rather serve a large image in smaller chunks.

If the server renders the entire image and just hands out the smaller 
images, I would not
expect the percieved transmission time to diminish, as the crucial part 
is the time that goes
before the initial image is displayed.

 From a users perspective, a long but visible progress, is better than a 
shorter uncertain wait.
(Within certain bounds of course)

Regards, Kenneth Skovhede, GEOGRAF A/S



Zac Spitzer skrev:
> Kenneth, do you think meta tiling could also solve this problem?
>
> On Thu, Jul 31, 2008 at 7:20 PM, Kenneth Skovhede, GEOGRAF A/S
> <ks at geograf.dk> wrote:
>   
>> The current tile mechanism is using static images to serve pre-built images
>> as tiles.
>> For this reason, the tiles are only usefull with "base layers".
>>
>> I have worked with OpenLayers, and it has a very nice tiling mechanism.
>> DM Solutions have built some tiling support into the MapGuide provider for
>> OpenLayers.
>> This uses the static tiles, and the row/column index system in MapGuide.
>>
>> Using the "original" OpenLayers tiling mechanism one can get a dynamic
>> MapGuide image
>> to load as tiles, giving the illusion that the page loads faster (when it
>> actually loads a bit slower).
>>
>> The problem with this method is that MapGuide optimizes the rendered image
>> for the given bounds.
>> This is especially true for calculating label positions and overlaps.
>> I would like to add a parameter for the "GETMAPIMAGE" call that accepts an
>> "outer bounds" parameter.
>>
>> With this parameter, MapGuide should render the extent given by the extent
>> parameter, but use the outer
>> bounds for determining label placements and any other details that may have
>> the same problems.
>>
>> With this, it would be possible for MapGuide to serve tiles from MapGuide,
>> without relying on a
>> static tilcache.
>>
>>
>> I would like to add this as an RFC, but would like feedback on the idea, as
>> well as possible problems.
>>
>> --
>> Regards, Kenneth Skovhede, GEOGRAF A/S
>>
>>
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>>
>>     
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