Monday, 23 November 2009

Snooping around!

A picture was posted on a blog. Perfectly innocently. Just a picture of a rainbow taken from a window.

But I wondered if there was enough information there to identify where the picture was taken from using Google Earth.

The text accomanying the picture tells me that this was taken in a place called Rathcoole, which is somewhere near Dublin.

Most of the ROI is only covered by low quality satellite imagery, indeed much of Ireland appears to be covered in lava. But I'd imagine that Dublin at least would merit some higher resolution aerial photography.

And there it is. Rathcoole. Just a bit South West of Dublin, on the N7 towards Naas (I hitch-hiked from Dublin to Waterford once, and one leg of my journey took me from South Dublin to Naas, so I probably got driven along it once, I think by a middle aged lady in a flowery dress). The airport at the top of the picture is called Casement Aerodrome, and is presumably named after Roger Casement, the famous revolutionary bloke from 1921 and all that.

Some of Google Earth at this point is hi-res, and some of it is low-res.

Now, what clues do I have to guide me closer?

The most obvious one is a road sign in the bottom right hand corner of the picture. There's a main road with another road bearing off to the left, just out of shot. The roadsign is in full sunlight, so the picture could not have been taken from the North, facing south. The text of the sign is too small to be legible, but the words appear to be quite long. Are Irish roadsigns written in English?, or Gaelic? Or both, as happens in Wales?

Well here's one I lifted from wikipedia...

So the signs are bilingual, with the gaelic first, but in lower case, and the English second but in upper case.

Some politics there, methinks, but the text is too small for me to identify anything useful.

Non-motorway national primary routes use white text on a green background, with the specific route number in yellow bold text.

So that puts my man next to a major road. The N7 or the N81 or the N82. There are lamp posts pretty much in the foreground, so the place this picture was taken from is close to a road. they're fairly far apart, so that also suggests quite a major road.

Although the time the photograph was taken is not stated, the sun never goes that far north, especially not at this time of year. It looks like it's pretty low in the sky, too, judging by the quality of the light, and the way the clouds are lit, almost horizontally.

Rainbows always appear beyond the viewpoint, directly in a line from the light source. See HERE for more information. The site linked contains loads of beautiful images and interesting information about all sorts of atmospheric phenomena. Not just rainbows.

Anyway, the higher the bow, the lower the sun, so this was definately taken either shortly after dawn or shortly before sunset. I suspect the latter. The man that took this picture can regularly be found posting stuff on discussion boards in the wee small hours, and he's known to enjoy the occasional recreational relaxant, so my guess is that he was safely tucked up under his duvet shortly after dawn on the day this picture was taken.

So the sun was in the west or south west, therefore the sunlight went from there to the east or north east, and therefore the camera must also have been facing either east or north east.

Here's Rathcoole rotated in Google Earth so that East(ish) is at the top...

So I'm looking for a place where an eastbound road has a road branching off towards the left/north.

In the background are low white buildings. They appear to be industrial units. It's certainly a more built up area than the fields in the near and middle distance. There are some buildings slightly in front of them that look like farm cottages or similar. The horizon is fairly flat, at least the bit of the horizon that isn't hidden by the raincloud is fairly flat.

The fields themselves form an identifiable pattern, as do the combination of ditches, fences and trees that form the field boundaries.

So, looking for a point just south of a major road, and just west of a point where that road contains a left fork, probably into another fairly major road, roughly a mile or so away from some white industrial looking units, with a rural landscape of fields filling the intermediate space.

so here's where I reckon it is...

Drumroll, please!

You can almost see his beard.


The photographer himself was kind enough to contact me and tell me almost exactly where the picture was taken from. Certainly got to within a mile or less, but more pertinantly, most of my logic was correct. It is a place just south of the N7. The camera was facing east, and the shot was taken in the late afternoon. If Google Earth had been using aerial photography in this location, rather than satellite imagary, I reckon I could probably have pinned down the street in which he lived, if not the precise house.

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