Under the Datum/Check name are a set of check boxes which define the way in which offset measurements are applied and allow for alter- native probe offset controls.
Measured Indirectly. At times, it can become necessary to measure a feature indirectly. Meaning for example, that you measure the table top to represent the bottom surface of a part clamped to the table. Normally the probing direction de- fines the way in which we handle probing offsets. However in this case, you are measuring a mating surface, changing the offset direction. To account for this, we have an option in the Feature Check properties dialog that allows you to specify that the measurements were taken indirectly.
Use Probing Direction. Probing direction is either the line of sight of the instrument (for a tracker as an example) or the direction vector recorded with a point taken by a 6D probe. Using this information typically ensures proper probe compensation.
Reverse Probing Direction. There are times when a reflector is visible on the far side of a part but the measurement was taken in the opposite direction of the line of sight. This option allows probe compensation to be manually set in the opposite direction from normal use.
Reverse Normal (Unique to Open Slots). The direction of an open slot or midplane is not well defined because it often is measured by the same instrument from 2 directions or by multiple instruments. Therefore a simple direction control is avail able.
Ignore Edge Projection. Surface Profile checks are allows a little flexibility based upon the extent of the surrounding sur- faces. This check box forces any points off the measured sur- face to be ignored.