24 August 2005

Speed issues

Filed under: Maps — Chris @ 19:11

Two people independently have raised the issue of update speed for the Flash maps when accessed by dial-up connections (thanks for your feedback guys!). Basically the map stays in its blurry state for too long while the detailed images load.
I’ve been considering the options for this and I think the best one by far is to introduce a set of intermediate scale image tiles – here’s the logic:

  • The map currently is 400 x 400 pixels (I’ve tried various sizes and I don’t want to go any smaller than that).
  • Zooming in, the Zoomify Flash interface loads images at 50% scale, so a total image size of 800 x 800.
  • With the current tile size (256 x 256) the number of tiles vertically and horizontally will always be 4 or 5, so the total number of tiles to form the image will be 16, 20 or 25.
  • By introducing the extra images I should be able to load at 70% instead, with a total image size of 566 x 566 so only 3 or 4 tiles each way – total number of tiles 9, 12 or 16.
  • On average I think I should end up loading about half the number of images for each view without increasing the individual image size.

So that’s the theory. In practice I don’t think it will be possible using the free Zoomify interface so will have to wait until I get my dHTML system going…

Any comments or other suggestions welcome.

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