OmniTek OTR 1001, Руководство пользователя

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OmniTek OTR 1001 User Guide, v3.1 I-9
I.4 Depth Analysis (Stereo 3D video only)
The OTR offers a range of displays analysing the depth information determined from the left and
right image streams. These displays are presented through three additions to the Picture category
of tile views:
Depth Map : This can be set to display all the pixels in the image for which the depth was
calculated. Alternatively, the display can be limited to just those pixels for which the
calculated depth is outside the specified Depth Budget.
Depth Plan : This can be set to show the distribution of objects from front to back as seen
from above or as seen from one side. Another option is to display the disparity values that
were determined as a plot across the width of the screen.
Depth Map Histogram : This displays a histogram, showing the distribution of disparity
values across the whole image and to what degree these are within the desired Depth
Budget.
These displays are described in Sections I.5, I.6 and I.7, respectively.
The displays all use a colour ramp to indicate position relative to the specified Depth Budget. All
points nearer to the viewer than the minimum distance are coloured red; all points beyond the
maximum distance are coloured violet. The colour ramp is used to colour points located between
these two distances.
Background
The distance from the screen that an object in a Stereo 3D video will appear to be to the viewer
is readily calculated by simple geometry. All the calculation requires is knowledge of the width
of the screen, the viewer’s distance in front of the screen, how far apart their eyes are (the
‘Interocular distance) – and knowledge of the ‘disparity’ between the position of an identifiable
point on the object – in the Left-eye image and its position on the same line of the Right-eye
image.
The result of the calculation for any point gives the ‘ z
’ component for this point in a set of
‘Viewer World Coordinates’, the ‘
x
’ and ‘
y
’ components of which are calculated assuming that
the viewer is sitting centrally with their eye level half way up the screen. (The (0, 0, 0) point for
these viewer coordinates is the centre of the screen.)
The width of the screen, the viewer’s distance in front of the screen and the Interocular distance
remain the same throughout the video and are recorded as part of the System settings (see
Configuration, below).
In analysing each frame of the video, the OTR searches along each line of the video for features
that can be matched between the left-eye image and the right-eye image. The range of the right-
eye image that is searched for a matching feature is given by the values for the Search Minimum
and the Search Maximum recorded in the System settings. These minimum and maximum values
set the limits on the range of disparity values that will be determined. They also correspond to
the nearest to the viewer and the farthest behind the screen that the OTR will pick out items to
report. Any objects with disparities outside this range in the video will not be reported.