1.19.1. Instruments used

The main instruments used in tacheometry are a tacheometer, and a levelling rod.

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.

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.

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.

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.

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.

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.

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.

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 used is similar to as used in levelling work.

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.

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.

To make the value of additive constant zero, an additional convex lens, known as anallatic lens, is provided in the telescope.

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.

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.

By having K=100 and C=0, the calculation work is considerably reduced.

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.

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!

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