Pengukuran Poligon Tertutup dan Detail pada Theodolite

Summary

This video tutorial explains the process of measuring a closed polygon using a theodolite in surveying. It covers setting up stakes to define survey points, adjusting the theodolite, and taking vertical and horizontal angle measurements at each point. The video also demonstrates the method for recording data, closing the polygon, and ensuring accuracy. The final part emphasizes compiling the data into a detailed report for mapping purposes. It provides essential steps for accurate surveying, from equipment setup to final data entry, ideal for those learning about geodetic or civil engineering measurements.

Takeaways

• 😀 The process begins by setting up reference points (stakes) at the corners of the measurement area, which are crucial for the polygon measurements.
• 😀 The first step in using the theodolite is to set up the instrument securely and check that it is level and properly calibrated before starting measurements.
• 😀 When measuring, the theodolite should be positioned at a reference point, with the orientation set to the North for consistency in the readings.
• 😀 Before taking measurements, the height of the instrument from the reference point (the stake) must be determined, ensuring accurate vertical angle readings.
• 😀 The theodolite is used to measure both horizontal and vertical angles, which are recorded as readings from the instrument's scale and the cross-hair lines.
• 😀 The setup and adjustments of the theodolite must be precise, including securing the instrument with a tripod and adjusting focus to obtain clear readings.
• 😀 Measurements are taken by rotating the instrument to target the next reference point (e.g., a tree or building) and noting both vertical and horizontal angle values.
• 😀 Once readings are taken, both horizontal and vertical angles should be noted, along with any necessary calculations for closed polygon measurement.
• 😀 The procedure for measuring the closed polygon involves taking multiple angle and distance measurements between a set of points, ensuring complete coverage of the area.
• 😀 After all measurements are recorded, the instrument is packed up carefully to prevent damage, and the data is transferred to a digital format for further analysis, such as creating contour maps.

Q & A

What is the first step in setting up for a closed polygon measurement using a theodolite?

The first step is to mark the key points on the ground (called 'patok') that will define the vertices of the polygon. These points are the locations where you will take your measurements.

Why is it important to set the theodolite to 'zero' at the northern reference point?

Setting the theodolite to 'zero' at the northern reference point helps establish a consistent baseline for all measurements. This ensures that angles are measured relative to a standard direction, which is crucial for creating an accurate polygon.

What should be done before taking any measurements with the theodolite?

Before taking measurements, ensure that the theodolite is securely positioned over the first point, levelled, and locked into place. The instrument should also be aligned using a plumb bob to ensure it is correctly positioned over the survey point.

What is the difference between 'normal' and 'abnormal' angles when using the theodolite?

Normal angles are the typical vertical and horizontal angle measurements taken during the survey. Abnormal angles, also known as 'outer' angles, occur when the theodolite is rotated 180° to measure angles in the opposite direction.

How is the data from the theodolite recorded during the survey?

Data is recorded by reading the vertical and horizontal angles on the theodolite’s display, including the measurements of the height and distance between the theodolite and the target points. These values are then noted for further analysis.

Why is it necessary to measure the height of the instrument during the survey?

Measuring the height of the theodolite from the ground level is important for calculating the elevation differences between the instrument and the target points. This ensures accurate readings, especially when creating contour maps.

What should you do if the angle readings appear inconsistent during the survey?

If angle readings are inconsistent, repeat the measurements to verify accuracy. It’s important to ensure the theodolite is correctly aligned and locked in place before each reading to minimize errors.

How does rotating the theodolite 180° affect the measurements?

Rotating the theodolite 180° switches the direction of measurement, allowing the surveyor to record the 'outer' or reverse angles. This is crucial for ensuring the closure of the polygon and for accurate data collection.

What is the purpose of recording horizontal and vertical angles during a polygon measurement?

Recording both horizontal and vertical angles allows the surveyor to define the precise location of each vertex in the polygon. These angles help in calculating the exact shape and size of the surveyed area.

What should be done after completing the polygon measurements?

After completing the polygon measurements, the surveyor should carefully record all the data, including angles and distances. The data is then used to generate detailed maps or to check the closure of the polygon to ensure the measurements are accurate.