It's clear that what obscures the view is the blue haze phenomenon.
However, like I said at the beginning of my previous post, the real useful informations that can be obtained from these data are when we are in the
presence of dark/contrasted areas, which is NOT the case ni our "UFO" photo. So any further radiometric analysis at this point is useless,
Anyway, and just to show you how technically it can be done, I have a very good example where this "haze study" can be done; it's in the photo below
that concerns an incident which took place during the hot-air balloons competition Mondial Air Ballon 2007 which was organized, as every year, on the
former military base of Chambley-les-Bussières (Meurthe-et-Moselle, France) in August 2007.
One of the participants to this meeting, who had shot 120 photos with his Nikon D200 digital camera, selected one of them, dated 5 August, on which
appeared, in the upper left corner, among hot-air balloons, a quite singular unidentified object.
Zoom on the object
The only visible elements of comparison in the scene photographed in Chambley are hot-air balloons. It was therefore important to make enquiries on
the size of such objects.
Investigation on Internet taught us that a standard air-balloon has a volume in the order of 2500 m3, a height of 20 m and a diameter of 15 m.
The photo was shot from the ground, with a Nikon D200 digital reflex camera focussed to infinity, with an exposure time equal to 1/6400 sec.
It was also shot against the sunlight and we may consider that the darkest parts of the objects of the scene were submitted to variations of their
apparent luminance mostly due to atmospheric diffusion. Consequently, we shall concentrate on the dark part of the unidentified object, as well as
that of both reference balloons.
In a quite empirical approach, we shall content ourselves with noting down the darkest pixel value in each of these three areas, using specialized
tool dedicated to the analysis of the radiometry of pixels within in a closed surface (here a red circle).
Dark level object = 24
The same for both reference balloons’ baskets.
Balloon 1 :
Dark level balloon1 = 30
Dark level balloon2 = 12
Assuming – which is highly probable – that the object and both reference baskets are really dark, we may conclude that the distance of the object
from the camera was somewhere between that of balloon 1 and that of balloon 2. In fact, those distances may be estimated, if we assume that both
balloons have a standard diameter Ф = 15 m :
Distance balloon1 = (Ф/2) / tan (δ ballon1 / 2) i.e.: Distance balloon1 = 391 m *
Distance balloon2 = (Ф/2) / tan (δ balloon2 / 2) i.e.: Distance balloon2 = 118 m *
Through linear interpolation on the darkest pixel values (an empirical approach), we obtain an estimate of the distance to the unidentified object:
Distance object = 300 m
From which we may derive an estimate of its actual length:
Length object = 2 x 300 tan (0,14°/2) i.e.:
Length object = 0,73 m
Taking into account uncertainties and calculation approximations, we can conservatively conclude that the length of the object – if it was actually
dark – was somewhere between 50 cm and 1 m.
(Should its color have been - in reality - lighter, its length could only have been less than this estimate).
* : with δ being the angular dimensions of the object.
edit on 4-10-2012 by elevenaugust because: (no reason given)
4-10-2012 by elevenaugust because: (no reason given)