Reporting

After the correction of every image, Cosima will create (on demand) a report file, both as pure ASCII textfile and as an HTML file, which can be opened with a browser. In the report, you find at first the image errors in a small table, here is an example:

Error analysis:

Mean error of height = 16 pixel (right image upturned)
Mean error of size = 0.44 percent (right image oversized)
Mean error of rotation = 0.089 degrees (approx. identical rotation)
Mean error of vergence_v = 0.82 degrees (convergent shooting axes)
Mean error of vergence_h = -0.069 degrees (approx. equal shooting levels)
Near point disparity = 8 pixel (near point behind stereo window)

The last entry measures the disparity of the near point in the original image. It is negative, if the near point is placed in front of the stereo window.

With the next table, the correction values of the last iteration are given. These values normally should be very small and will converge for longer iterations against zero. If there are matching errors of corresponding image points, these values may keep large and possibly no image will be rendered. Here is an example of a successful image correction:

Image analysis after the last iteration:

Mean error of height = -0.13 pixel
Mean error of size = 0.072 percent
Mean error of rotation = 0.013 degrees
Mean error of vergence_v =-0.0042 degrees
Mean error of vergence_h = 0.0087 degrees

Because the stereo window values after the image correction are so important for the perception of a stereo image, they are summarized with a further table:

Stereo window after the correction:

Far point disparity = 70 pixel
Near point disparity = 8 pixel
Absolute deviation = 62 pixel
Relative deviation = 1/28 of the image width
...= 36 Promille

The absolute image deviation is the difference of the far point disparity and the near point disparity, in this case 70 pixel - 8 pixel = 62 pixel.
To compute the relative deviation, this value is related to the image width (in this case the image width = 1740 pixel: 62/1740 = 1/28 = 0.00356 = 36 promille).
(If the parameter ProjectionRatio specifies a fixed projection ratio, the relative deviation is additionally given in relation to the width of the projection image.)

These stereo window values will now be tested against the following 3 tests: the deviation test, the far point test and the near point test.

If no projection ratio was specified, the deviation is based to the available image width.
However, if the parameter Projection Ratio specifies a width-to-height ratio of the projected image, all 3 tests are performed on the base of the width of the projection image.

1. Deviation test

The 70-minute condition by Hermann L├╝scher will be applied to an image, which is observed with a presence of 0.6.
(The presence is the ratio of the projected image width and the distance to the screen, please see http://www.herbig-3d.de/german/minuten.htm, chapter 2.3.)
For that projection situation, deviation values larger than 1/30 of the image width will lead to an image decomposition independent on the stereo window framing.

If 1/15 < deviation:
The deviation is definitely too large for both print and projection.
The image unsuited for publishing!
If 1/20 < deviation < 1/15:
The deviation is definitely too large for projection!
The image only suited for prints!
If 1/30 < deviation > 1/20:
The deviation may be critical for huge projection (depends on image content)!
The image is suited for prints!
If 1/100 < deviation < 1/30:
The deviation is optimal. The image is suited for both prints and projection.
If deviation < 1/100:
The deviation is too small for a typical stereo image.

2. Near point test

The near point will be set automatically by the program or manually by the user. Near point disparities < 0 are possible results from the automatic only with the setting EstimateWindow = 3 and 5, otherwise they must be produced by the user itself. Cosima creates the following messages:

If near point disparity < 0:
If EstimateWindow = 3, 5: Near point as designed in front of the stereo window, please check effect!
If EstimateWindow = 0, 1, 2, 4: Warning: Near point in front of the stereo window,
stereo window condition probably violated!
If 0 < near point disparity < image width/50:
Near point close behind the stereo window, favourable stereo mounting.
If image width/50 < near point disparity:
Warning: Near point very far behind the stereo window, unfavourable mounting!

3. Far point test

Finally, a far point test is performed, which is extremely important, especially with near point framing. Cosima creates the following messages :

If image width/15 < far point disparity:
Warning: far point disparity definitely to large, painful projection!
If image width/20 < far point disparity < image width/15:
Warning: critical far point disparity, please avoid huge projection -
or adjust projectors to set the stereo window in front of the screen!
If image width/30 < far point disparity < image width/20:
Warning: far point disparity may be critical (depends on image content),
please avoid huge projection -
or adjust projectors to set the stereo window in front of the screen!
If far point disparity < image width/30:
Far point disparity is tolerable, the audience will be grateful.