Reading Horizontal Angles

Angles are a fundamental part of measurement in 2-D and 3-D surveying. While modern total stations have almost completely replaced optical and electronic theodolites for most work, the need to measure angles has not changed. While total stations are designed to support measurement of large numbers of single observation measurements, such as are used for topographic surveying, there is still a need for precise and reliable angle measurements for control, setting-out, construction and other tasks.

This report discusses instrument construction and internal operations, because this is needed to understand why the recommended observation procedures are done as they are. Both optical and electronic reading systems are presented, so that the differences may be understood. As it happens, the same procedures that were developed for optical theodolites can be applied with only minor modifications to electronic theodolites and total stations. The nature of systematic errors in instruments are discussed, and the methods that are built into the observation procedures to eliminate them are presented.


The observation procedures are set out in tables to that you can see how to record and reduce the observations. A spreadsheet is included in this package that shows how the reduction process is done. This Excel spreadsheet also includes a group of macros, which can be copied to other spreadsheets. These macros convert observations entered in various angular notations into radians (which the spreadsheet requires for its calculations), and vice versa. While these macros are copyright, as a purchaser of this package you can copy these macros for your personal use as often as you need.

This 73-page report uses gon as the angular units (centesimal system), and is written using UK English. It is downloaded after purchase as a Zip file, which contains the PDF report and the Excel spreadsheet. Once you have purchased the report, you can return to your account and download it again, or download any updated versions, at no additional charge.

Available now through the Wollindina Media Store for US $2.99 or equivalent in other currencies.