Data Collection Procedures for the Total Station

In the first step of the process, the field survey, the vertical and horizontal angles are measured along with slope distances using the total station. The angle and distances are stored with a point number and description in the data collector. The survey data are then transferred to the microcomputer via a cable connection for data processing and field data storage. The microcomputer is either an in-office desktop system or a laptop model that can be used on site.



a. The data are then processed in the microcomputer to produce a coordinate file which contains point number, point code, X-Y-Z coordinate values, and a point descriptor.

b. Once the data are on the workstation, they are converted into a graphics design file for use in a CAD program such as Micro Station or AutoCAD.  Level, label, symbol, and line definitions are assigned to each point based upon point code. The program can transform data into a two dimensional (2D) or three-dimensional (3D) design file.

c. The 3D file is used to create the digital terrain model (DTM) which is used to produce the contours & Sections. The resulting topographic data are then plotted for review. Final editing and addition of notes are completed, yielding topographic data in a digital format or as a plotted map.

d. Uniform operating procedures are needed to avoid confusion when collecting survey data. The use of proper field procedures is essential to prevent confusion in generating a map. Collection of survey points in a meaningful pattern aids in identifying map features.

Coding Field Data

Whether data are recorded manually or electronically, one of the most time-consuming survey operations is the recording of a code or description to properly identify the point during processing. For example, in a topographic or planimetric survey, identification points which locate the position of curbs, gutters, center lines, manholes, and other similar features are essential for their correct plotting and contour interpolation.

a. Especially in topographic or planimetric surveying, many surveyors have wished for some way to speed up the process. For the most part, surveyors tolerate the time-consuming coding process, because it is the only way of ensuring an accurate final product.

b. In spite of this slow coding process when using data collectors available today, the advantages heavily outweigh the disadvantages. These advantages include collection blunder-free numeric data from electronic total stations virtually at the instant they are available and the error-free transfer of these data to an office computer system without the need for manual entry.

c. Field coding allows the Surveyor to become the drafter and provide a more logical approach, as the field Surveyor can virtually produce the map from the field data and eliminate the need for many field book sketches. They can also eliminate office plotting, editing by connecting the dots, etc., to produce a final product. The coding scheme is designed so the computer can interpret the recorded data without ambiguity to create a virtually finished product.