PDA

View Full Version : West of Heathrow - one plane, two shadows discussion



manxIX
06-07-2009, 08:25 PM
This is a discussion thread for the following file:<br><br><b><a href=http://www.gearthhacks.com/dlfile32100/West-of-Heathrow---one-plane,-two-shadows.htm>West of Heathrow - one plane, two shadows</a></b><br><br>The same location as http://www.gearthhacks.com/dlfile32098/Airbus-A340-from-Qatar-Airways.htm but here you can see that there is one original plane with two shadows. For the second shadow there is no photographed original, it seems to be vanished. Very strange...<br /><br /><img src=http://www.gearthhacks.com/showimage.php?image=112807/8334251.jpg>

manxIX
06-07-2009, 08:34 PM
Hi
Surely you mean one aircraft THREE shadows.

The correct shadow, if you follow the direction of the thrown shadows, is on the squareish reservoir almost due north of the aircraft.

That leaves the problem(s) of the other two shadows to the west. Higher flying aircraft perhaps?

Why 3 aircraft throwing shadows in almost the same place, at the same time and over the busiest airport in the world?

Well spotted and very hard to explain.

geronimo
06-09-2009, 08:14 AM
Thanx for your correction. You are right, there are THREE shadows. Very mysterious...

SpiderX22
06-09-2009, 11:59 PM
File edited so that "two shadows" is now "three shadows" to avoid further confusion.

Fritriac
06-17-2009, 06:29 PM
Looks like shadow #3 is the original one (just look at the shadow direction of the power poles in the west of the plane).

So why? Not all pics from Google Earth are satellite photos, the most of them (with much better quality) are aerial photos from planes. So when each of these photos covers -let's take a number- 600m x 600m of the ground, the plane takes one photo every ~500m. Then the next series, 500m away from the first flight path etc.

Later the single photos are stacked together with some graphics software and - voilá.

But: To avoid gaps in the resulting picture, the photos have to overlap!

Here a scenario:

Photo plane on its first flight path
Photo 1-1: Plane and shadow are both on the picture
Photo 1-2: Plane and shadow on the picture, but plane in the overlap-area
Photo 1-3: Shadow is still on the pic, plane is outside

Photo plane on its next path, 500m to the south
Photo 2-1: No plane, doesn't affect 1-1
Photo 2-2: No plane, overlaps plane on 1-2
Photo 2-3: No plane, overlaps again

My scenario, let me show you it ;) :

http://www.fritriac.de/looky/gearthhacks/overlap_sm.jpg

Link to a bigger version (http://www.fritriac.de/looky/gearthhacks/overlap.jpg)

I know a guy who does exactly this (not actual taking the aerial photos but processing photos this way). The software they use is really sophisticated: You don't need to stack photos per hand anymore, different saturations and/ore hues will be automatically corrected, soft transitions ... yadda, yadda, yadda.

Maybe this will also clarify some other "map quirks" ... :spin:

Appletom
06-17-2009, 07:21 PM
This has to be the best explanation - with photographic evidence [complete with with circles and arrows and a paragraph on the back] for missing planes (or, conversely, for missing shadows) I've seen yet.

Thank you Fritriac!!!

I'm bookmarking this thread for reference for the next time someone asks "Where's the shadow?"