5.1.5. Field Procedure of Total Station Survey

1. Setting up the Total Station on a tripod and leveling it.

The first step in the Total Station survey involves placing the Total Station instrument securely on a tripod. This tripod must be stable to ensure accuracy in measurements. After the instrument is positioned, it must be leveled using built-in leveling screws to ensure the instrument is horizontal. A properly leveled instrument is crucial for accurate angle and distance measurements since any tilt can introduce significant errors in the collected data.

Imagine trying to take a picture with a camera while it is tilted. The photo will come out distorted. Similarly, if the Total Station isn’t level, the measurements will be ‘distorted,’ leading to inaccurate survey results.

2. Centering the instrument using the optical plummet.

Once the Total Station is leveled, the next step is to center it directly over the survey point. This is done using an optical plummet, which is a small telescope mounted on the instrument that points straight down. The surveyor looks through this device and adjusts the tripod legs until the optical plummet is directly aligned with the point on the ground. Accurate centering is essential because any offset can lead to errors in location data.

Consider trying to hit a target with a dart. If you’re not standing right over the target, it’s difficult to aim accurately. Centering the Total Station over the survey point is like positioning yourself correctly to hit the target.

3. Inputting station data (coordinates, instrument height).

In this step, the surveyor enters essential information into the Total Station. This includes the coordinates of the location (eastings, northings, and elevation), as well as the height of the instrument above the ground. This data is important for calculations related to the elevation and angle of the measurements taken from this point. Accurate input ensures that the subsequent data collected will be correctly referenced.

Think of this like entering your current location into a GPS device before starting your journey. If you input the wrong starting point, the directions given will be incorrect, leading you off course.

4. Sighting the prism and measuring angle and distance.

After the station data has been inputted, the surveyor sights a prism that is placed at the target location. The Total Station uses a laser or infrared beam to determine the distance to the prism and simultaneously measures the angles. This encompasses both horizontal and vertical angles relative to the instrument's position. The measurements are typically displayed on the Total Station's screen within moments, allowing for real-time data collection.

This step is much like pointing a laser pointer at a spot across a room. Once you know where the laser points (like the distance and angle to the spot), you have a clear idea of where you want to go next!

5. Recording and storing data.

After measuring the angle and distance, the surveyor must ensure the collected data is recorded. The Total Station often has built-in memory or the capability to connect with data collectors or computers for data storage. It’s critical to ensure this data is logged accurately because it forms the basis for subsequent calculations, analysis, and final reporting.

Think of this like writing down important notes during a lecture. If you don’t record the information accurately, you might forget it or confuse it later when you need it for studying.

6. Transferring data to computers for post-processing.

Once all necessary measurements are recorded, the final step is to transfer this data to a computer or specialized software for post-processing. This could involve further calculations to refine positions, transformations to specific coordinate systems, or integrating the data into mapping software. Proper data transfer ensures that the information is kept safe and can be analyzed or reviewed in detail.

It's like saving a document on your computer after working on it. You want to ensure that your hard work is secured and can be easily accessed later for editing or sharing.

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