1.6. Maps

One of the basic objectives of surveying is to finally prepare various types of maps useful for engineering works (Survey Manual, 2014). Maps are graphical representation of Earth surface features to some scale.

Maps serve a fundamental purpose in surveying by providing a graphical representation of features on the Earth's surface, effectively allowing for various engineering works. They depict geographical information in a visual and scaled manner, making it easier for engineers and planners to analyze and utilize the data accurately. Essentially, maps translate the complex real-world into a format that can be understood and manipulated for planning and construction.

Think of a map like a recipe for cooking. Just as a recipe gives you the ingredients and steps needed to create a dish, a map provides the essential 'ingredients' (landmarks, natural features, etc.) necessary for planning construction projects and understanding geographical contexts.

Two broad types of maps; planimetric and topographic, are prepared as a result of surveys. The former, called plan map, depicts the natural and cultural features in their plan (x-y) views only, while the latter includes planimetric features, and the elevation (z) of ground surface.

There are two main types of maps used in surveying: planimetric and topographic. A planimetric map focuses only on the x-y view, representing features such as roads and buildings without showing changes in elevation. In contrast, topographic maps integrate both horizontal and vertical information, meaning they display the terrain's elevation and contours, giving a three-dimensional perspective of the landscape. This distinction is crucial for engineers and planners who need to understand both the layout (where things are) and the topography (how high or low they are) of the land they are working on.

Imagine you're going hiking. A planimetric map would show you only the paths and locations of campsites, while a topographic map would not only show those paths but also the hills and valleys you would encounter. This information is vital when planning your route to ensure you don’t encounter unexpected steep climbs or difficult terrains.

Maps depict the locations as well a relief of natural and cultural features on the Earth's surface (Garg, 2021). Natural features normally shown on maps include forests, vegetation, rivers, lakes, snow, oceans, etc., while cultural features are the man-made features and include roads, rails, buildings, bridges, tower, canal etc.

Maps are designed to convey both natural and cultural features of an area. Natural features encompass elements like forests, rivers, lakes, and oceans, showcasing the geographical and environmental context. Cultural features, on the other hand, represent human-made structures such as roads, buildings, and bridges. This combination provides an invaluable resource for those needing to understand the interplay between natural landscapes and human development, which is critical for effective planning and decision-making.

Consider a city map. It shows you where the parks (natural features) are along with the roads and buildings (cultural features). If you want to plan a park day with friends, you need to know where the park is—and how to get there amidst all the buildings and streets!

Traditionally, engineering maps have been prepared using manual drafting methods and plane table survey. With the availability of digital data from total station, GPS, laser scanners and digital images form photogrammetry and remote sensing, now the majority of maps are produced using computers, computer-aided drafting (CAD), and GIS software.

Traditionally, maps were created through manual drafting techniques, which involve a significant amount of time and human effort. The introduction of digital tools has transformed this process. Today, technologies such as GPS, laser scanning, and remote sensing enable rapid and highly accurate data collection. This data is then processed using specialized software like CAD and GIS to produce detailed maps efficiently. This shift not only enhances accuracy but also reduces the time needed for map production, allowing more rapid responses in engineering and planning.

Think of it as going from cooking a meal by hand to using a microwave. Initially, cooking required you to chop, simmer, and taste each ingredient manually. Now, with microwaves and pre-prepped ingredients, you can whip up a meal much faster without sacrificing taste, similar to how digital methods expedite map creation without losing detail and quality.

The natural and cultural features on the maps are depicted graphically by points, lines and polygons, with different symbols and colours. For example, the relief of the Earth includes its hills, valleys, plains, slopes and other surface irregularities, which are represented in the form of contour lines.

Maps utilize graphical representations to visually convey information about the Earth’s features. Points, lines, and polygons represent various features such as mountains, rivers, and buildings. Colors and specific symbols provide additional context; for example, blue usually indicates water, while green represents forests. Contour lines illustrate variations in elevation, showing how steep or flat areas are. This visual representation allows users to quickly interpret the landscape and make informed decisions about land use or construction.

Imagine a visually appealing infographic. Just as it uses colors, shapes, and symbols to convey information quickly and attractively, maps provide an instant understanding of geographical layouts. If a tourist is looking at a map of a national park, they can easily see where the hiking trails (lines) are compared to the high mountains (contours) and lakes (points) just by looking at the colors and symbols used.

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