Surveying, Mapping, and Geodesy Fundamentals

Surveying, Mapping, and Geodesy

Surveying

Surveying is a set of technical and scientific operations used to determine the spatial position of points to represent a plane land surface and its elements. Common units used in surveying include:

• Length: meter
• Area: square meter or hectare (10,000 m²)
• Angle: Grad

Cartography

Cartography is the science that studies the different methods and systems used to represent part or all of the Earth's surface on a plane.

Geodesy

Geodesy is the science that studies the shape and dimensions of the Earth.

Map Projections

Map projections aim to minimize distortions caused by transforming a three-dimensional surface into a two-dimensional plane. These distortions can be linear, angular, or surface-related. Different types of projections address these distortions:

• Equivalent Projections: Preserve areas and are commonly used in cadastral operations.
• Conformal Projections: Preserve angles and are useful in navigation and surveying.
• Automeca Projections: Preserve distances in a specific direction.

Universal Transverse Mercator (UTM) Projection

In the UTM projection, the Earth is divided into 60 zones, each 6 degrees wide. These zones are numbered 1 to 60 from the antimeridian of Greenwich, going west to east. Each zone is further divided into 20 areas, labeled with capital letters. This results in 1200 zones (60 x 20), each designated by the zone number followed by the area letter. For example, Eastern Andalusia is located in zone 30S, and Granada is in the 100-square-kilometer VG grid square.

Geographical Coordinates and Direction

• Longitude: The angle formed by the plane of the Greenwich meridian and the plane of the meridian of a given location. Longitude is measured east and west of the Greenwich meridian.
• Latitude: The vertical angle between the ellipsoid at a given point and the plane of the Equator. Latitude is measured north and south of the Equator.
• Azimuth: The horizontal angle measured clockwise from north to the direction of an object or fixed point.
• Bearing: Similar to azimuth, but can be measured clockwise or counterclockwise from north.

Route Surveying

Route surveying is a planimetric method used to obtain the X and Y coordinates of points called "stations." These stations serve as the basis for detailed surveying by radiation. There are different types of routes:

• Oriented Itineraries: Reference axes are parallel, and the axis orientation is done with the instrument in the field.
• Confused Itineraries: The previous station is not placed at the opposite azimuth, and only the angle formed by the alignment is recorded.
• Open Route: The start and end points do not match, and their coordinates are unknown. This type of route should be avoided.
• Framed Itinerary: The route starts and ends at different points with known coordinates.
• Closed Route: The route starts and ends at the same point. This is the most common type.