1.19.1 - Instruments used
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Tacheometry Instruments
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Welcome class! Today we are diving into the instruments used in tacheometry. Can anyone tell me what a tacheometer is?
Isn't it a special type of theodolite?
Exactly! A tacheometer is a type of transit theodolite with unique features that help us measure distances accurately. What do you think is special about its construction?
It has stadia hairs, right?
Correct! The stadia hairs consist of three horizontal lines that aid in measuring the distance. Remember the acronym **SHD** for Stadia Hairs Diaphragm. Can anyone tell me why we use anallactic lenses in a tacheometer?
They help keep the additive constant zero?
Right! By using an anallactic lens, we simplify our calculations, making fieldwork much more efficient. Great job, everyone!
Function of Levelling Rod
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Let's discuss the levelling rod now. Why do you think it’s essential in tacheometry?
To measure vertical distances?
Yes! It helps us determine vertical distances, especially in combination with the tacheometer. What do we typically use the levelling rod for?
To reference a base point when taking measurements?
Exactly! It acts as a reference for measuring distances and elevations. Remember, in tough terrains, tacheometry simplifies these readings compared to chaining or taping. Any questions?
Advantages of Tacheometry
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today let's explore why tacheometry is preferred for surveying in challenging layouts. What advantages do you think it holds?
It is faster than traditional methods?
Yes, very good! It is much quicker and more efficient in rough terrains. How does it compare to chaining?
It's more accurate in difficult areas, right?
Correct! In rough or swampy areas, tacheometry reduces the chances of error. Let’s remember the terms **FAST** for Faster, Accurate, Simplified, and Terrain-friendly. Keep these attributes in mind!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section describes the instruments used in tacheometry, primarily the tacheometer, which incorporates specialized elements like stadia hairs and an anallactic lens, enhancing measurement accuracy. Additionally, it covers the role of the leveling rod in determining distances in varied terrains.
Detailed
Instruments Used in Tacheometry
In tacheometry, the accuracy of distance measurement is significantly enhanced using specific instruments. The primary tools are the tacheometer and the levelling rod. A tacheometer is a specialized type of transit theodolite fitted with a stadia diaphragm, which incorporates three horizontal hairs (known as stadia hairs) to facilitate precise distance measurements over horizontal and vertical terrains. The effective use of anallactic lenses within these instruments ensures that the multiplying constant (K) is maintained at 100, while the additive constant (C) is set to zero, allowing for simplified calculations in the field.
The levelling rod, utilized similarly to those in simple levelling work, aids in distance measurement. These instruments are particularly advantageous in challenging terrains like steep, undulating grounds or swampy areas where traditional chaining or taping is less effective. Tacheometry is thus a preferred method for field observations requiring rapid and accurate distance determinations.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Tacheometer Overview
Chapter 1 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
The main instruments used in tacheometry are a tacheometer, and a levelling rod.
Detailed Explanation
The primary instruments for conducting tacheometry are the tacheometer and the levelling rod. The tacheometer is an advanced form of a transit theodolite equipped with special features that aid in precise distance measurement. The levelling rod, on the other hand, is a stick marked with measurements that helps in determining vertical distances.
Examples & Analogies
Think of the tacheometer like a high-tech camera that not only captures pictures but also measures how far away things are. The levelling rod is like a measuring tape used to check how high something is when you take a picture.
Basic Structure of a Tacheometer
Chapter 2 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
A tacheometer is a transit theodolite where the telescope is fitted with a special diaphragm, called stadia hairs, i.e., a diaphragm fitted with three horizontal hairs; one at the top, another in the middle and third at the bottom of diaphragm.
Detailed Explanation
A tacheometer includes a telescope equipped with stadia hairs, which are three horizontal lines spaced evenly. These hairs help in ensuring accurate readings when using triangulation methods to measure distances. The way these hairs are positioned aids in quickly calculating distances by measuring the differences in sightline with the levelling rod.
Examples & Analogies
Imagine a string of three lights spaced apart on a fishing line. When you look through the telescope at the levelling rod, you can see how much of the rod spans between those lights, which helps you figure out how far away it is, just like gauging the distance with points of reference.
Tacheometer Specifications
Chapter 3 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
The term tacheometer is restricted to a transit theodolite which is provided with an anallactic lens in the telescope. The essential characteristics of a tacheometer are that the value of the multiplying constant (K= f / I) should be 100 and additive constant (C= f + d) should be zero.
Detailed Explanation
The tacheometer is specifically designed with an anallactic lens that corrects measurements, ensuring both precision and simplicity. It operates using two essential constants - a multiplying constant (K), which is typically set to 100, and an additive constant (C), which should be zero. These constants help in simplifying calculations, reducing the chances of error.
Examples & Analogies
Think of the tacheometer like a specialized calculator that not only adds numbers but also scales them perfectly. It’s like a recipe card that tells you a fixed amount of each ingredient needed to make sure your dish turns out just right, ensuring accuracy in cooking.
Levelling Rod in Tacheometry
Chapter 4 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Levelling rod used is similar to as used in levelling work.
Detailed Explanation
The levelling rod used in tacheometry shares characteristics with those used in traditional levelling work. It helps provide precise height readings when conducting measurements related to vertical distances.
Examples & Analogies
Consider the levelling rod like a yardstick at a school. Just as a yardstick is used to measure how tall children are during roll call, the levelling rod measures the height difference which is crucial in ensuring accurate tacheometric readings.
Use of anallatic Lens
Chapter 5 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
To make the value of additive constant zero, an additional convex lens, known as anallatic lens, is provided in the telescope.
Detailed Explanation
In order to assure that the additive constant equals zero, a specific lens called an anallatic lens is included within the telescope setup. This adjustment is critical for improving the accuracy of measurements during tacheometric operations.
Examples & Analogies
Picture a pair of glasses that not only helps you see better but adjusts how you view distances as well. This lens makes sure that your view doesn’t distort the sizes or distances of objects, allowing you to focus purely on what’s being measured.
Benefits of K=100 and C=0
Chapter 6 of 6
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
By having K=100 and C=0, the calculation work is considerably reduced.
Detailed Explanation
With the constants set to K=100 and C=0, the calculations for determining distances during tacheometric measurements are made more straightforward. This greatly reduces the complexity of mathematical operations needed to derive distances, enhancing efficiency in surveying.
Examples & Analogies
Think of this as using a shortcut in a complex board game. Instead of following a long path filled with obstacles, you find a direct route that allows you to win more quickly. It's all about simplifying what should otherwise be complicated!
Key Concepts
-
Tacheometer: A specialized instrument for distance measurement in tacheometry.
-
Stadia Hairs: Three horizontal hairs in the instrument used for accurate spacing measurements.
-
Anallactic Lens: A lens that negates the additive constant in the measurement process.
-
Levelling Rod: Instrument assisting in vertical distance measurement.
Examples & Applications
Using a tacheometer with stadia hairs to measure the distance to a tree in hilly terrain.
A surveyor employing a levelling rod in a swamp to take vertical measurements.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
For heights that we'd scale, we use the tacheometer scale!
Stories
Once upon a time in the hilly terrain, a surveying crew used a tacheometer with stadia hairs and a levelling rod to guide their way through difficult landscapes, measuring distances with ease and accuracy!
Memory Tools
Remember the acronym TAL for Tacheometer, Anallactic lens, Levelling rod to recall the main instruments!
Acronyms
Use the word **SHD** for Stadia Hairs Diaphragm to remember the role of the tacheometer.
Flash Cards
Glossary
- Tacheometer
A specialized transit theodolite used for measuring distances with enhanced accuracy.
- Stadia Hairs
Three horizontal lines in the tacheometer's diaphragm used for measuring distance.
- Anallactic Lens
A lens used in a tacheometer to ensure the additive constant is zero for simplified measurements.
- Levelling Rod
A rod used to measure vertical distances in conjunction with surveying instruments.
Reference links
Supplementary resources to enhance your learning experience.