Summary of How to Find Height of Inaccessible Point Using Theodolite | Unknown Height | Civil Surveying.

Summary of "How to Find Height of Inaccessible Point Using Theodolite | Unknown Height | Civil Surveying"

This video explains the process of measuring the height of an inaccessible point, such as a Minaret or Tower, using a Theodolite and related surveying instruments. The key concepts and methodology covered include instrument setup, angle measurement, distance measurement, and height calculation by combining these data points.

Main Ideas and Concepts

Purpose: To measure the height of an inaccessible point (e.g., Minaret, Tower) using surveying instruments without physically accessing the point.
Instruments Used:
- Theodolite (referred to as "retail" or "leave light" in subtitles)
- Measuring tape (for distance measurement)
- Ranging rods or markers
Setup:
- Position the Theodolite at a known point on the ground, at a measurable distance from the object.
- Ensure the instrument is leveled and properly aligned.
Measurement Process:
- Sight the top of the inaccessible point through the Theodolite telescope.
- Measure the vertical angle (angle of elevation) to the top of the object.
- Measure the horizontal distance from the instrument setup point to the base of the object using a tape.
Calculations:
- Use the angle of elevation and the horizontal distance to calculate the height difference between the instrument and the top of the object using Trigonometry (height = distance × tan(angle)).
- Add the height of the instrument above ground level to this calculated height to get the total height of the object.
Adjustments for Ground Level Differences:
- If the instrument is set up on uneven ground or the base of the object is not at the same level, measure the reduced level (RL) difference.
- Add or subtract this RL difference to the calculated height to get the true height above a reference level.
Recording and Accuracy:
- Carefully record the angle measurements (degrees and minutes).
- Ensure accurate distance measurement.
- Double-check calculations to ensure correct height estimation.

Detailed Methodology / Step-by-Step Instructions

Instrument Setup:
- Set up the Theodolite at a convenient point from where the inaccessible point (e.g., Minaret) is visible.
- Level the instrument properly.
- Note the height of the instrument from the ground (height of the instrument).
Distance Measurement:
- Measure the horizontal distance (D) from the instrument setup point to the base of the inaccessible object using a tape or Ranging rods.
Angle Measurement:
- Using the Theodolite telescope, sight the top of the object.
- Record the vertical angle of elevation (θ) in degrees and minutes.
Height Calculation:
- Calculate the height difference (h) using the formula:
  h = D × tan(θ)
- Add the height of the instrument (hi) to this height difference:
  Total height (H) = h + hi
Adjust for Ground Level Differences:
- If the ground level at the instrument setup point and the base of the object are different, measure the reduced level (RL) difference (ΔRL).
- Adjust the total height accordingly:
  Corrected height = H ± ΔRL
Final Result:
- The corrected height is the height of the inaccessible point above the reference ground level.

Speakers / Sources Featured

Instructor / Speaker: A Civil Surveying instructor or demonstrator explaining the procedure to students or trainees.
Students / Assistants: Briefly mentioned as participants helping with measurements or observing the demonstration.

Additional Notes

The video emphasizes practical surveying in the field, using common instruments.
It highlights the importance of accurate angle and distance measurements.
The approach is suitable for civil engineering, construction, and surveying tasks where direct measurement is not possible.
The explanation includes some references to taking readings in degrees and minutes and converting them for calculations.
The method relies on basic trigonometric principles applied in surveying.

This summary captures the core instructional content of the video despite some transcription errors in the subtitles.