Rodenstock ImpressionIST 4+ - Selection of Measuring Points; Calculation of Individual Parameters; Figure 6-6: Selection of All Measuring Points in the Central Image in both Slice Planes

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© Rodenstock GmbH
Status: September 2023
6.4.2 Selection of measuring points
The measuring point selection is a three-step procedure
• Automated preselection of the pupils in the two images with manual correction option.
• Automated preselection of the edge points of the disc anterior surfaces in the horizontal and vertical
planes, depending on the pupil center selection. Performed in both camera images for each half of the
face.
• Each automatic preselection must be checked and reselected if necessary.
• Selection of the frame horizontals and the 3D box nasal/bottom - temporal/top.
In Figure 67 you can see all selected measuring points from the evaluated images of the two cameras. The 3D
data is projected into a two-dimensional view, so the boxes are not rectangular.
Figure 6-6: Selection of all measuring points in the central image in both slice planes
6.4.3 Calculation of individual parameters
Optionally without or with correction of the head rotation to the mount plane. The angle of rotation is displayed in
the output field after evaluation.
▪ Monocular (Inter-)Pupillary distance R/L (PD):
Definition according to DIN EN ISO 13666: Distance between the center of the pupil and the centerline of the
nose or the bridge of the spectacle frame in case the eye is in primary position.
▪ Corneal vertex distance R/L (CVD):
Definition according to DIN EN ISO 13666: Distance between the back surface of the lens and the vertex of the
cornea, measured in the direction of gaze perpendicular to the frame plane (Figure 68 red line).