Re: Deeper Zoom

Kyle Mulka wrote:

> > Does this add a lot of overhead to the server to make the
> > slices on the fly like this?
> Yes, it adds a large amount of overhead if you don't do any caching.
>
> > Is serving indiividual tile
> > images still faster, and if so, can you automatically cache the tiles?

In the case of Terra-Server, the only way I am aware of retrieving raw
tiles is via their UTM coordinates. The tiles are 200 x 200 pixels
rather than the standard 256 x 256 pixels used by everybody else.

I like the approach suggested by Kyle. Unfortunately, the ugliness at
UTM zone boundaries still exists. Try a map in which the longitude
degrees are exactly divisible by six. If you pan east / west, you will
see what I mean.

Terra-Server is quite fast which may mean nobody uses it. The
"GetImageArea.ashx" interface does add another layer of chopping tiles
& JPEG compression but it eliminates dealing with UTM coordinates & a
non-standard tile size. It is fast enough for many applications.

One area of concern is pixel alignment. The "GetImageArea.ashx"
interface uses latitude / longitude paramters to fabricate tiles.
Rounding errors could cause adjacent tiles to be skewed by one pixel.
With raw tiles, it will never happen.