Target height

The value you enter in the Target height field depends whether you are measuring the true height of the prism or to the notch on a traverse prism base. The default method is to measure the true height of the prism.

The dual notch Trimble traverse kit has two notches:

  • The S notch corresponds to the Bottom notch on a Trimble VX or S Series instrument or a Spectra Geospatial FOCUS instrument.
  • The SX notch corresponds to the Bottom notch on a Trimble SX10 or SX12 scanning total station.

The S notch on the dual notch traverse kit is equivalent to the single notch Trimble traverse kit.

When measuring the target height to the notch on a Trimble traverse prism base, tap in the Targets screen and select the appropriate measurement method:

  • Select S notch when measuring to the notch on the single notch traverse kit, or to the S notch on the dual notch traverse kit.

  • Select SX notch when measuring to the SX notch on the dual notch traverse kit.

The S notch measurement method replaces the Bottom notch measurement method in previous versions of Trimble Access. The SX notch measurement method is new in Trimble Access version 2019.10.

The Trimble Access software corrects the measured slope value to true vertical and adds the appropriate offset value to calculate the true vertical height to the center of the prism.

Value Definition

Ho

Offset from the notch to center of the prism. The value of the offset depends on the selected notch on the prism base:

  • S notch: 0.158 m (0.518 sft)
  • SX notch: 0.138 m (0.453 sft)

Hm

Measured slope distance.

Hc

Hm corrected from slope to true vertical.

HT

True vertical target height. Hc + Ho.

If you select S notch or SX notch, the minimum slope distance (Hm) that you can enter is 0.300 meters. This is approximately the minimum slope distance that can be physically measured. If the minimum is not low enough, you must measure the true height to the center of the prism.