1.4. Types of Surveying

The two broad types of land survey used are plane surveying and geodetic surveying, depending upon whether the spherical shape of the Earth is taken into account or not (Punmia et al., 2016).

In surveying, there are two main categories based on how they view the Earth’s shape. 'Plane surveying' treats the Earth as flat, while 'geodetic surveying' takes its curvature into account. This distinction is crucial because it affects measurement techniques and the applicability of survey results. Understanding which type to use is essential for the scale and scope of the surveying project.

Think of it like using a flat map compared to a globe. If you’re only looking at a small area, like a city, a flat map (plane surveying) is good enough. But if you’re trying to understand how continents fit together, you need a globe (geodetic surveying) to see the actual curvature of the Earth.

In plane surveying, the Earth surface is considered as a plane surface, and its spheroidal shape is neglected. For small projects covering area less than 250 sq.km, Earth curvature is not accounted for distance measurements. The line joining any two stations is considered to be straight, and three points will make a plain triangle. Surveys for engineering projects fall under this category. Plane surveying uses normal instruments, like measuring tape, theodolite, level, etc., and the survey accuracy is low.

Plane surveying simplifies the Earth’s surface to a flat plane for practical purposes. It's suitable for smaller projects, such as building sites or roads, usually covering areas up to 250 square kilometers. Within this scope, all lines are treated as straight, and triangles formed by measurements help to define the surveyed space. The instruments used are fairly standard and may lead to lower accuracy, which is often acceptable for smaller tasks.

Imagine a carpenter measuring a piece of plywood. He treats the surface as flat because it helps him cut it accurately without worrying about any curvature. Similarly, engineers use plane surveying for straightforward projects where high precision isn’t critical.

This type of surveying takes into account the true shape of the Earth. Earth curvature correction is applied to the observations. The triangle formed by any three points is considered as spherical. Geodetic surveys are carried out for areas greater than 250 sq.km. For large areas, degree of accuracy of measurements is high, and therefore geodetic survey requires sophisticated and high precision equipment, like the GPS, Total Station. Geodetic survey is used to provide control points to which small surveys can be connected.

Geodetic surveying acknowledges the Earth as a sphere, which is important for larger projects. For areas exceeding 250 square kilometers, understanding and correcting for the Earth's curvature is vital to ensure accuracy in measurements. This method employs advanced tools such as GPS and Total Stations, which can provide high precision results, making them essential for large-scale surveying where reliability is critical.

Think of a large sports field compared to a small backyard garden. If you’re marking out a soccer field, you’d want to consider the curvature of the Earth to ensure the goalposts are truly straight and aligned over a large distance. So, you’d use geodetic surveying techniques and tools that provide that high level of accuracy, just like stadium planners do to make sure everything fits perfectly.

Surveys can be further classified into several categories depending on the purpose, instruments, techniques used, etc.

Surveys can be categorized based on various criteria such as their intended purpose, the instruments used, and the techniques applied. This classification helps professionals choose the right method for their specific needs, ensuring efficient and accurate data collection. Understanding these categories is vital for anyone involved in surveying as it directly impacts the planning and execution of surveying projects.

Consider a chef preparing different dishes; each recipe requires different ingredients and methods. Similarly, surveying needs different categories based on what it needs to achieve, whether it's establishing land boundaries (cadastral surveying) or measuring water depths (hydrographic surveying). Each type serves a unique purpose, just as each dish has its own recipe.

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