1.4 - Example 1.22: Calculation of Tacheometric Constants
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Introduction to Tacheometric Constants
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Today, we will explore the calculation of tacheometric constants, 'K' and 'C'. Can anyone tell me what these constants represent in distance measurement?
Isn't 'K' the factor that relates the staff readings to the actual distance?
Exactly! And 'C' is the constant offset we need to account for. These are critical for accurate distance measuring in tacheometry. Let’s define our formula: D = KS + C. Can someone identify what 'D', 'S', 'K', and 'C' are?
'D' is the horizontal distance, 'S' is the staff reading, 'K' is the distance constant, and 'C' is the offset.
Perfect! By using the given horizontal distances and stadia readings, we can derive equations to find 'K' and 'C'. Let’s proceed with an example.
Setting Up Equations for Tacheometric Constants
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From our example, we have two sets of observations. First off, from the first reading, we have 45 meters and three stadia readings. Can someone write the equation for these readings?
Sure! For the first set, we can write: 45 = K(1.335 - 0.885) + C.
Correct! And what about the second reading for 60 meters?
It would be 60 = K(2.460 - 1.860) + C, right?
Exactly! Now, we have two equations. Let’s solve them step by step.
Solving the System of Equations
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We have our equations set up. Who can detail how we can find 'K' by eliminating 'C'?
We can subtract one equation from the other to cancel 'C', and that will help us solve for 'K'!
Precisely! By equating those terms, we simplify the calculations. Now, what do we get when we manipulate these equations?
After simplification, we get K = 100!
Well done! Now, how can we find 'C'?
We substitute 'K' back into one of the original equations to solve for 'C'.
Yes! Thus confirming that 'C' equals 0. This shows our constants are accurately defined.
Understanding the Significance of Tacheometric Constants
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Can anyone summarize why understanding 'K' and 'C' is essential for surveyors?
They help us convert staff readings accurately into ground distances which are crucial for mapping and construction.
Correct! Without these constants, our calculations for distance would be erroneous. Why is precision critical in surveying?
Because even small errors can lead to significant impacts in construction projects.
Excellent point! As we wrap up, remember to practice these calculations as they're fundamental to effective surveying.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section provides a detailed explanation of how to calculate tacheometric constants 'K' and 'C' from given stadia readings at specified horizontal distances. It walks through the mathematical formulations and their significance in surveying practices.
Detailed
Example 1.22: Calculation of Tacheometric Constants
In tacheometry, distances are determined from the readings taken on a leveling staff with a tacheometer. This section illustrates how to compute the tacheometric constants 'K' (the multiplying factor) and 'C' (the additive constant) using given horizontal distances and stadia readings. The tacheometric formula can be expressed as:
D = KS + C
where:
- D = Horizontal distance,
- S = Staff reading,
- K = Constant relating to distance measurement,
- C = Constant offset.
In this example, the horizontal distances and three stadia readings at each point provide two sets of equations. By equating and solving these equations, we can derive the values for 'K' and 'C' that reflect the observational data precisely. These constants are essential in tacheometric surveying as they help in converting staff readings into precise ground distances.
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Introduction to Tacheometric Readings
Chapter 1 of 4
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Chapter Content
The following readings were taken with a tacheometer on to a vertical staff, calculate the tacheometric constants.
Horizontal Distance (m) Stadia Readings (m)
45.00 0.885 1.110 1.335
60.00 1.860 2.160 2.460
Detailed Explanation
This section introduces the concept of tacheometric readings, which are used to determine horizontal distances based on angles and distances recorded with a tacheometer. The readings taken at two different horizontal distances (45 m and 60 m) with associated stadia readings show how the instrument can measure differences in staff positions, allowing a surveyor to compute necessary constants for further calculations.
Examples & Analogies
Think of a tacheometer like a high-tech measuring stick that combines a ruler and a protractor. Just like you might measure how tall someone is by using a wall as a reference and a tape measure from a certain distance, the tacheometer uses these measurements to estimate distances to objects or points without directly measuring them.
Understanding the Tacheometric Equation
Chapter 2 of 4
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Chapter Content
Solution:
D = KS + C ................................(1)
1 1
D = KS + C ................................(2)
2 2
Detailed Explanation
The tacheometric equation relates the horizontal distance (D) to the stadia readings (S) through two constants (K and C). The constants help to calibrate the readings taken by the tacheometer. In simple terms, K determines the scale of the measurement, while C accounts for any systematic biases in measurement. These equations show two separate tacheometric readings that lead to the same horizontal distance calculation.
Examples & Analogies
Imagine you're baking cookies. The recipe requires specific ratios of ingredients (like flour and sugar) to get the right taste (the final outcome, which would be the distance in our case). K acts like the amount of flour you add, modifying how sweet or savory the cookie will be. C shows how much sugar was already in the batter, helping adjust the overall flavor without needing to change what you started with.
Setting up the Equations
Chapter 3 of 4
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Chapter Content
So, 45 = K (1.335 – 0.885) + C
45 = K (0.45) + C ....................(3)
60 = K (2.460 – 1.860) + C
60 = K (0.6) + C ………….….(4)
Detailed Explanation
In this step, we set up two equations (3 and 4) based on the readings provided. Equation 3 comes from the first distance measurement of 45 m, and Equation 4 from the second measurement at 60 m. Each equation uses the differences in stadia readings to form a linear relationship between K and C. This creates a system of equations that can be solved simultaneously to find K and C.
Examples & Analogies
Think of it like solving a mystery using clues. Each clue (the equations formed) gives you important pieces of information (the values of K and C). By gathering all st clues to figure out who dunnit (solving for K and C), we get a clearer picture of the situation.
Solving for the Constants K and C
Chapter 4 of 4
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Chapter Content
Equating C from equations 3 and 4, we get-
45 – K (0.45) = 60 - K (0.6)
0.15K = 15
K =100
Now put the value of K in either equation 3 or 4, we get C =0
Detailed Explanation
Here we manipulate the equations to isolate C by equating it from both equations (3 & 4). This leads to the discovery of the value of K as 100. Substituting K back into either of the original equations allows us to solve for C, which turns out to be 0. Understanding these constants is crucial for accurate distance calculations in surveying work.
Examples & Analogies
Imagine if you were given coordinates to places on a map but needed to understand the specific distance between them. By solving these equations, you can determine the exact measurement and make precise calculations for your travel plan, just like using K and C in surveying.
Key Concepts
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Tacheometry: The methodology used for determining distances based on staff readings.
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Constants K and C: The two critical constants used in the tacheometric formula.
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Stadia Principle: A principle underlying the assessment of measurements in tacheometry.
Examples & Applications
Calculating the horizontal distance using given stadia readings and deriving 'K' and 'C'.
Using the formulas to determine distances and validate precision in surveying applications.
Memory Aids
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Rhymes
With K and C we measure far, converting readings like a star!
Stories
Imagine a surveyor meeting a giant where the staff represents the giant's height. He calculates the distance to a castle using constants, K and C, finding his way through the forest of measurement.
Memory Tools
Remember K for Kilometers and C for Constant when calculating distances!
Acronyms
KCD
is for distance
is for correction
is for the derived value.
Flash Cards
Glossary
- Tacheometry
A branch of surveying that enables the measurement of distances by using a tacheometer with stadia readings.
- Stadia Readings
The readings obtained from a leveling staff used to derive distances using a tacheometer.
- Tacheometric Constants
The constants 'K' and 'C' that are fundamental to calculating distances in tacheometry.
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