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A short class with Sarah and her students. The other ways are under More.
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Today, we'll look at a practical problem involving Electronic Distance Measurement, or EDM. Who can tell me the basic principle of how EDM operates?
EDM measures the distance by calculating the time it takes for a signal to travel to a target and back.
Exactly! And we also need to consider the instrument's height. Why do you think height matters?
Because it can affect the true distance if we don't correct for it!
Right! The height of the EDM and the reflector above the ground must be accounted for in our calculations. Can anyone share how we find the horizontal distance?
We need to use trigonometry based on the vertical angle!
Correct! Remember to keep your triangle definitions in mind, particularly how they relate to the angle of elevation. Let's summarize: When measuring, always adjust for equipment height and apply trigonometric principles for accuracy.
Now, let's dive into the actual problem. We have a total measured distance of 714.652 m. Who remembers how to apply height corrections here?
We need to deduct the heights of the EDM and the reflector because we want the horizontal length.
Exactly! Good job! Now, we also need to deal with the vertical angle of +4°25′15″. How does this fit into our calculations?
We'll use the tangent function because we need to find the opposite side in relation to our angle.
You're on the right track! By calculating the horizontal distance using the cosine of the angle, we can effectively find the length. So, to summarize, we first adjust our measured distance, then apply our angle to get the horizontal measurement.
To find the length that's straight, cosine helps us relate.
Imagine hiking up a slope, you measure and hope. But first, correct for height, then find your way with trigonometric might.
H.A.T. stands for Height, Angle, and Trigonometry - the key to finding true distance!
H.E.A.D. - Height, EDM, Angle, Distance - Remember these four for sonic precision!
Term
What is the primary function of EDM?
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Term
How is horizontal distance calculated?
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An electronic device used to measure distances by transmitting a signal to a target and back.
A surveying instrument for measuring horizontal and vertical angles.
The angle measured with respect to a horizontal plane, indicating the height of an object.
The distance measured along a slope which requires correction to obtain horizontal distance.
The straight line distance on a horizontal plane, typically found using trigonometric calculations.
This section presents a practical numerical problem related to measuring distances using EDM and theodolite.
An unsolved numerical question involves calculating the horizontal length of a line measured with an EDM along a slope and corrected for various factors using a theodolite for vertical angle measurement. The exercise tests knowledge of geometric relationships and measurement corrections.
In this section, we are presented with a numerical problem that requires understanding of distance measurement techniques. The example outlines a scenario where a distance is measured along a slope using an Electronic Distance Measurement (EDM) instrument. The measured distance must be corrected for the height of the instrument and the reflector above ground, as well as the vertical angle measured to the target. The key approach to solve this problem involves applying trigonometric principles and geometric relations to derive the horizontal length of the line in question. Understanding how to incorporate corrections for atmospheric conditions and equipment constants is critical in achieving accurate results. This section emphasizes the practical application of surveying principles to real-world measurement situations.