Derived Vertical Axis Limits

This dialog shows you the number of samples in each trace, the vertical sample interval, and the total length of the trace based on those values.  Units default to milliseconds and the most common time interval is 4 ms or 4000 µs.   When you change the interval, the total length of the trace is immediately recalculated.

You must also specify the vertical units to be assigned.  For seismic reflection and refraction time data, milliseconds (ms) or microseconds (µs) are used.  Ground Penentrating Radar (GPR) data are typically stored as nanoseconds (ns).  For Depth sections or volumes, meters and feet are supported.

For 2D surveys, the units selected will affect the annotations along the vertical axis, units displayed, the location and size of any grid generated, and registration of the BMP within GM-SYS Profile Modelling. 

For 3D surveys, the choice of vertical units will affect the scaling of any voxel produced.  This is particularly important for Geosoft voxel output, because a voxel with 4 µs vertical cell size will display at 1/1000 the vertical dimension of (the equivalent) 4,000 ms cell size.