We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Object distances from camera 60 (in rhos)
— ->XB+ REGION
_ -^ — _ ^ _
7717 Region of / \S_ divergence I
B REGION
\l \
N factors at M= 218 No
Ni(ZCL=0)
Fig. 11. Graphical analysis of "human vision" technique (i.e., tc fixed at 2.5 in.).
For M = 21 8, fe = 50mm, all depth range possibilities are comprised in a series of parallel lines, such as those shown at 10p intervals, in the horizontally shaded region bounded by B = 0. For p values > 60 (distances < 8 ft 4 in.), extend the graph upward; forN> 3, extend it to the right. For/c > 50mm, the parallel lines slope proportionately less steeply, and the depth range decreases ; for fe < 50mm, these lines slope more steeply, and the depth range increases. For M > 218, the region of divergence extends to the right, the intervals N0, NI, N2 . . . becoming proportionately smaller, NI remaining at zc = 0.
mission lines on the graph will have the same slope, and must therefore run parallel to one another.*
Figure 1 1 displays all the possibilities of such a transmission system, assuming tc = 2.5 in., and taking M = 218 and fe = 50 mm (i.e. 1.97 in.), so as to enable a direct comparison to be made with the shooting of Slate 15 of The Black Swan.
Then, from Eq. (8b),
* When the focus and convergence are coupled, this statement is not strictly true, for fe is properly the lens-to-film distance, which increases slightly as the lens is focused nearer. Hence, as DI is brought nearer to the camera, the C factor will increase slightly and the depth range will be correspondingly reduced. This is a secondorder error, which is ignored in Fig. 11.
D1
2.5 X 6,000 218 X 1.97 X 2.5
rhos 13.97 rhos.
This enables us to draw the B = 0 line in Fig. 11, which also shows representative transmission lines drawn in at arbitrary intervals of lOp. The area under the B = Q line represents the B — type of transmission, which gives rise to cardboarding and is therefore almost always undesirable; hence the camera convergence must never be set to give DI less than 13.97p (i.e. di more than 35 ft 9 in.). When the lenses are focused at infinity, they must not, as might be expected, be aligned with their axes parallel; alternatively, if the lens and convergence mechanisms are coupled, the lenses must
Spottiswoode, Spottiswoode and Smith: 3-D Photography
277