Knowledge Base

Category: SurvCE
Topic ID: 430
Title: Leica Prism Offsets
Created: 0000-00-00Last modified: 0000-00-00
Leica Prism offsets differ from other manufacturers prism offsets.  Carlson SurvCE accounts for this within the program.

Click below to download a PDF document with Screenshots:

Leica Prism Constants in SurvCE 2.0

To my knowledge according to the Leica Manual if you have a prism constant and you need to solve for the “Leica Constant” you would take the Leica Constant value of 34.4 and subtract your Prism value from it.

For instance if you have a 30mm standard prism you take 34.4 {Leica constant} – 30mm {prism constant} = 4.4mm

In this example a positive 4.4mm is used for the “Add Constant” in the Leica Equipment.

I ran a test using SurvCE Version 2.09 with a Leica 1100 Total Station.

You can check your SurvCE Version by tapping the Equip tab then tapping “About SurvCE”.

For the purpose of discussion lets refer to the Leica terminology as it is displayed on a Leica 1100 when I go into Menu / 5 Configuration / 1 Instrument Configuration / 02 Reflector Selection while I’m set in SurvCE to 4.4 (30mm) as shown in the screenshot below.

In SurvCE it is in the format of Add Const. (Reflector List) where “Add Const” is the physical value added to the Slope Distance and “Reflector List” is the proper name of the Prism and the stamped value on the prism itself.

Reflector List: 30mm
Add Const: 4.4mm

If you take a shot with a 0.0 “Add Const” and then reshoot it again with a “4.4 (30mm)” the slope distances would be displayed like the example below if all were shot to the exact same Physical Prism:

0.0mm = 6.562 feet {2.000 m}
4.4mm = 6.577 feet {2.0044 m} – Leica added 4.4mm to the Slope Distance