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Stereophotography guidelines

The process of stereoscopic viewing with eye

• Assume an average eye-seperation of 65.5 [mm] (Ferwerda [1990], page 220, section 21.8)
• The eye lens separation changes due to the turning of the lenses when converging to near by objects. The effect can be seen below, the eye lens separation reduces some 4.5% for objects at 250 mm distance (compared to objects at infinity).
  
  
• The deviation on the eye's retina, due to an object at a distance of focused distance, is (this includes the above changing eye lens separation):
  
  
  
  
  In the above picture the change in focal length of the human eye (slide 6) has been calculated for a lens system that is fully in the air (so back F_water~22.22 [mm] or front F_air~16.67 [mm]).
  The On-Retina Deviation (ORD) as a result of the eyes properties and the focused distance is also given.
• FoV with stereo (binocular) overlap is around 120 degrees wide and 135 degrees high
  

Ferwerda's guidelines for taking stereo photos

• All the homologous points should be on the same height in both pictures
• There should be no objects on the edges of the pictures which are closer by then the stereo window distance (w). These would cause window violations.
  
• The On-Film Deviation (d) is determined by the parallax (p) and Fc (d=Fc*2*tan(p/2)).
  
• The camera base (b0) is (from stereo window distance and infinity):
  b0 = d*(w*1000-F_c/2)/F_c [mm]
  This is Special case No. 2 in this link.
• The stereo window distance (w) is appr. half the hyperfocal distance (Ferwerda [1990], page 22, section 1.4).
  
• The minimum diaphragm is (assuming 2.25' point acuity, 45 cm view distance, 36 mm film, camera on infinite and halving f_min due to stereo photo (Ferwerda [1990], page 81, section 8.4)):
  f#_min = 3*F_c²/w  (Hawkins [1980], page 70-71)
• The pictures need to be fairly sharp in the range of w to 33w (Ferwerda [1990], page 116, section 10.12). This relaxes the above f_min-boundaries with one stop with a camera's focused distance at 2*w (based on own research).
  
• The convergence distance (c) should be bigger than (to minimize the keystone effect):
  c >= 25*n_h*b0/F_c [mm] (Ferwerda [1990], page 99, section 9.7)
  
• Parallax: p = 2*atan (b0/2/w/1000) [°] (Ferwerda [1990], page 237, section 24.4)
• Number of depth size between stereo window distance and infinity:
  z = p/stereoacuity [-] (Ferwerda [1990], page 236, section 24.2)

A stereoscopic subject finder

• The stereoscopic subject finder.
  The distance between the centers of the two finder holes: dfh = e - 65*z/(w*1000) [mm]
  The size_h,v of the finder holes: sfh_h,v = n_h,v * z/F_c  [mm] (Ferwerda [1990], page 90, section 8.10)

Guidelines for displaying stereo photos

• check that no barrel or pincushion distortion is present, otherwise correct (like with PSP, a script for FujiFilm FinePix 2600Zoom and FinePix E510 is available). For the FujiFilm FinePix REAl 3D W1 the results are here.
  

Barrel (when negative; pincushion) strength within PSP,
when compensating pictures made with Fujifilm FinePix 2600Zoom


Barrel (when negative; pincushion) strength within PSP,
when compensating pictures made with Fujifilm FinePix E510

• check that homologous points in each picture are not rotated from each other, otherwise compensate (with help of AnaBuilder or SPM)
• check that the scale of each picture (best checked with [virtual] surfaces that are really perpendicular to the direction the picture was take) is the same, otherwise compensate (with help of AnaBuilder or SPM)
• all the homologous points should be on the same height in both pictures (with help of AnaBuilder or SPM)
• if there are no infinite points use a slightly smaller separation of:
  eyeseparation - (distancepicture/farthestobject_act*(eyeseparation/2)) [mm] (displaying/mounting to farthest)
• the separation between the two right sides (and left sides) of the photo should be 0.2 [mm] smaller than the distance between the two most closest homologous points.

Ferwerda's guidelines for camera configuration
A more general calculation  is at another page.

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36*24 mm camera with zoom
Stereo Realist
Verascope
Fujifilm 2600Zoom digital camera

Focal length:                   to  [mm]                        
Diaphragm:                      to  [-]
CCD/croppedslide sizeh:        [mm]
CCD/croppedslide sizev:        [mm]
Interchange horizontal and vertical CCD/slide sizes
desired stereo window distance:[m] (nearest point distance)
Farthest point distance:       [m]
desired focal length:          [mm]
try to keep  stereo window distance or  focal length fixed.

Viewing/projection conditions

Stereo viewing method:         parallel
crossed
Red Button Realist viewer (Fv=44 mm)
Viewing parallax:              [°] (deviation angle due to stereo window distance and infinity and no convergence)
Displayed picture sizeh:       [mm]
Displayed picture distance:    [mm]
Stereo acuity:                 ["]
Point acuity:                  [']

 recommended values for:
stereo window distance            [m]
focal length (Fc)                 [mm]
diaphragm (f#)                  >=[-]
focused distance                  [m]
stereo base                       [mm]
convergence distance            >=[m]
number of depth steps             [-] (between stereo window distance and infinity)
on-film/CCD deviation             [mm]
on-displayed picture deviation    [mm]

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Major content related changes: March 20, 2005