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HDView team release DeepZoom gems in their code

Oct 17, 2008 at 3:04 PM

Some absolute gems in this code that we could most defn use. Apart from the obvious code to use the HDView tile format - nice to show HDView processed images geolocated the real gem is the way they have implimented a continuous horizontal panning.
They use 3 MSI controls synced with a 1 pixel overlap (kind of obvious) but the key to controlling this smoothly is to turn off the springs in the MSI and impliment the nice enertia that it would normally provide manually by binding to the "CompositionTarget.Rendering" event (with some logic to make this less CPU intensive based on user interaction).

Apart from obviously a cool feature where we could off a continous horitontal panning for DeepEarth and the ability to centre on New Zealand or where ever this could actually solve some of our other issues relating to the high number of calls and wobble effect of the MSI control.

There is quite a lot to consider and we may want to branch a prototype unless someone is dedicated enough to crunch through this alone. We would have to ensure that two parts of the earth are not shown at the same time and that pins, lines and polygons as well as everything else worked across the 3 MSI controls. If it is doable - I think it is  - would you want this as optional (lot more work). Can anyone think of why you wouldn't want this enabled? Would you use DeepEarth for Tilesets that are not the complete Earth and do not join?

Oct 17, 2008 at 3:34 PM
in the demo I notice you are not able to drag the image "Up & Down" just "left and right"

does that mean that it would be like that for the DeepEarth version too? or that just for there demo image?
Oct 24, 2008 at 6:27 AM
I have put together a quick hack of the HDView silverlight code:

Sample site here:

Download the code:

There would be a significant impact on this project and increased complexity for all aspects. I see this as more a Version 2 thing. What do you think?
Oct 24, 2008 at 7:02 AM
Looks pretty cool, you think you could make the map not only scroll east/west, but also from north/south...?
or would this just me a nightmare to try and work out?
or is just not the way things are working,
as I notice on the HDView site they also only have scrolling along one axis either, east/west or north/south in there demos
Oct 24, 2008 at 12:23 PM
I personally like being able to zoom way out to a smaller map (Not a huge fan of the continuous map). From a pure technical standpoint, it will put a lot more responsibility in our hands. Currently we rely quite a bit on the single MSI for a lot of stuff. If we had three of them, wouldn't we have to replace a lot of the logic that we currently rely on the MSI control for? Also, DeepZoom can be quite a resource hog when it is just a single control.
Oct 24, 2008 at 12:25 PM
Also, if we did want to allow the continuous pan across both axes, we would need 9 MSI controls. Ouch!
Oct 24, 2008 at 4:37 PM
That's awesome! All though good points by smbecker and this is something that we should try for V2.
Oct 24, 2008 at 6:14 PM
Edited Oct 24, 2008 at 6:22 PM
The world doesn't wrap North-South ;) So we wouldn't ever need it in the other direction.
I completely agree about it adding complexity to the project and also about the perf issues. Defn a Version 2 thing unless we provide an abstraction for the MSI control to handle all this seperatly. Then maybe a Version 1.x feature, I'm pretty keen to wrap up the functionlaity for the 1.0 release based on what we have listed currently as tasks and get something out there stable.