Knee Deep in Satellite Debris

March 1st, 2009

Click to view the live satellite debris tracker

A quick update on the Google Earth browser plugin based tracker displaying the debris from the collision between the Iridium 33 and Cosmos 2251 satellites on February 10th.

I mentioned the possibility that the number of fragments tracked in the Norad orbtial elements might increase. Well they have. Threefold over the past week, from 134 up to 406.

Remarkably the application still smoothly animates all objects in real time, even on my single core PC, but inevitiably it sucks up more processing power. You may find it now lags on an old machine or slower browser. If the number increases further I may have to either cap the number displayed or ditch the smooth animation.

Anyway, click on the image above to see it in action.

Related: Here’s a neat simulation from Analytical Graphics which includes a statistical break-up model of the satellites immediately after impact.

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New Imagery in Google Earth

February 28th, 2009

spot_the_differenceGoogle Earth Blog reports a stack of new high resolution imagery in Google Earth today (Feb 28th 2009) USA, France, Scotland, Africa, Iceland, Mongolia + many other places. Check out Frank’s post for up to date details.

Typically there’s a delay of a few days between this appearing in Google Earth and Google Maps, which means for a short while the Google Maps vs Earth plug-in side by side code example I mashed-up last year does something useful! It allows you to instantly compare the before and after.

A doddle to use this:

  • Switch to satellite view in the left map panel.
  • Type in a place name or address to fly instantly to that location in both maps.
  • Or drag one map and the other map will move too.

Full(ish) screen version here,
Or embedded below.

Read more…

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Satellite Collision Debris Tracking in the Google Earth Plug-in

February 23rd, 2009

Live Satellite Debris TrackerFollowing on from my visualization of the satellite collision over Siberia on February 10th involving Iridium 33 and Cosmos 2251, here’s an Google Earth browser plugin based tracker for the debris from the crash.

Full screen version here: http://barnabu.co.uk/geapi/debris

The application loads up to date Norad orbital elements on start up, and propogates the orbits of all 134 fragments smoothly in real time.

Remarkably the Google Earth API is powerful enough to move placemarks thousands of times a second to give the impression of completely smooth motion for hundreds of objects. On top of that modern browsers are fast enough to run all the Math heavy orbital computation in Javascript. So this is really-real-time tracking, not with delayed updates. Something that can’t be done in regular Google Earth.

I’m guessing the number of objects could increase over time as more wreckage is discovered. If that’s the case, just have to see how well it scales.

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Chrome support for the Google Earth Plugin

February 20th, 2009

Google has just announced, the Google Earth browser plugin is now officially supported by Google Chrome 1.0+. That means no more annoying ‘unsupported browser’ message for Chrome users. If you already have the plugin installed, you won’t need to download anything extra - should work automatically.

To give it a trial run check out Google’s demo gallery. Or my own apps here.

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Tours and 3D animation

February 19th, 2009

Looking around the various tech reviews of the new Google Earth 5, one new feature seems to have slipped under the radar - the KML tags describing the new touring function include a seriously powerful method for defining smooth motion 3d animation.

I’ve been messing around with this a little, and hacked together a few basic (not much KML code), slightly weird ;) , but dramatic examples. These are tours - view them by loading them into GE and double clicking on play me! in the side panel.

Fly wingman with a 3d model plane (also see the vid above)

Polygon morph France into Spain!

Dot-to-dot tour of European cities

How do these work ?

With the new <gx:AnimatedUpdate>. A container for the <Update> element. Which allows you to temporarily modify KML, and specify a length of time for that action to take place over.

Switching features on and off during a tour is the obvious example. Not so apparent, because it’s not directly available through tour recording inside Google Earth, is that for many other changes GE will smoothly interpolate (tween) the difference.

The example Google provide gradually increases the size of a placemark. But this effect can be applied to any KML attribute taking a range of values - orientation, colour, scale and coordinates. Significantly, these transitions will work in parallel, sequentially, across multiple features and alongside scripted camera movements.

This is powerful stuff! A much more convenient and concise method of animation than time slider hacks, where every intermediate step needs coding in KML. Only real downside in all this - and I guess it could be a biggie depending on your needs - you can’t fly around at will during tour playback.

About the examples

  • The first uses a single <gx:AnimatedUpdate> to gradually change location of a 3d model over a 60 second duration. Code for this below the fold if anyone wants to check it out.
  • Second does the same to transform all 38 coordinates in a polygon.
  • Last example combines a series of linestring coordinate transformations with color and scale changes for placemark icons.

Read more…

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