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IDV Silverlight Virtual Earth Map Viewer



Alright!  We have just posted a simple Silverlight 2.0 map viewer that pulls in Virtual Earth map imagery and lets you navigate their quad-key tileset.  This navigator is step one in our set of Silverlight mapping applications demo; more to come!  Be sure to get the latest Silverlight 2.0 plugin.

What is new?

Pseudo Physics
As map clients grow into more natural model of the world, the inclusion of simulated physics provides a more natural realm of interaction.  We all have certain expectations for interacting with things in the real world, namely the conservation of momentum and friction.  To not factor those into a user experience is to introduce the absolutely foreign (and creepy) concept of snapping in and out of existence.  So our map viewer has a velocity vector (speed and direction) to replicate the feeling of momentum.  Objects in motion tend to stay in motion.

But in addition to conserving momentum, friction is a critical element.  When you throw our map, it glides then comes to a stop.  Some interfaces continue momentum forever, like a frictionless ether.  But here on earth, things eventually come to a rest.  They ease out of their velocity vector.

This viewer is also different from some Silverlight image navigators in that it grips when the mouse is pressed so when you want to drag that map you drag the map, rather fanning it in the desired direction.

Navigation Paradigm
This navigation interface is a departure from our previous layouts, and incorporates some of the ideas discussed in IDVUX, the flyer vs. reeler discussion in particular.  We have oriented the zoom-out input to the top, and the zoom-in input to the bottom, to reinforce the notion of flying down for a closer look.  The zoom down nature is a more naturally mapped interface widget.

We retained the zoom slider, rather than two in/out throttle controls for two reasons:
1) It is the fastest, best way we have found to dive in and out quickly.
2) It is a great indication of status.  You see how much zoom-room is available above you and below you.  It is a worthwhile visual element even if you don’t drag it.  I am reminded of the great Mitch Hedberg…

"I like an escalator because an escalator can never break, it can only become stairs. There would never be an escalator temporarily out of order sign, only an ‘escalator temporarily stairs. Sorry for the convenience.’"

Why?  Not because it is useful in 2D in any way, but it’s just neat.  And for research demos, neat counts!  So there is a disk around the representational globe that connotes the cardinal directions, and the disk can be rotated, driving the rotation of the map view.

It is interesting how entrenched we are in our north-centric expectations.  Try this -turn on aerial map style then align east towards the top of the screen (that’s what someone in the middle ages would expect as the norm).  Very obvious landmarks become hard to recognize!

Also, you can throw the disk, replicating the last thing a doomed parachutist sees.

The rotation feature is also a gateway feature for when a 3D client is released -where rotation becomes essential.  And see that globe?  One fine day it will be a navigation input in addition to a nebulous indication of down.

Have fun.  Silverlight is a new beast and we are still learning the benefits of a vector engine driven by markup.  It is a fun ride.  Justin Hoffman, our senior developer, is digging in and architecting some fantastic things; more to come.




John Nelson / IDV Solutions / john.nelson@idvsolutions.com


25 responses

  1. John

    Simply awesome John. I\’d love hear some more on how you find Siverlight2 compared to your Flash viewer.
    Also since you mentioned neat features, have you considered allowing the map to wrap? That is allowing you to pan left from the US to Australia. That would be neat.

    April 24, 2008 at 5:53 pm

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