Short Answer:

Photogrammetry in surveying is used to create maps, measure distances, and analyze land features using photographs taken from drones, airplanes, or satellites. It helps surveyors capture accurate data over large areas quickly and efficiently. This method is useful in civil engineering for planning roads, bridges, and infrastructure projects.

Photogrammetry allows engineers to extract 3D information from 2D photos by processing overlapping images. It is widely applied in topographic mapping, land use studies, urban planning, mining, and construction monitoring. It saves time and cost while providing detailed and reliable spatial data for survey-based decisions.

Detailed Explanation:

Applications of photogrammetry in surveying

Photogrammetry is the science of making measurements from photographs. In civil engineering and surveying, it plays an essential role in gathering accurate spatial information without physical contact with the land. By taking images from aerial platforms such as drones, aircraft, or satellites, photogrammetry allows professionals to measure, map, and model the Earth’s surface and structures.

Photogrammetry mainly uses overlapping images of an area taken from different angles. Using special software, these images are processed to generate 2D maps and 3D models of terrain, buildings, or other features. It helps in visualizing the actual shape and elevation of land without visiting every point.

Key Applications in Surveying:

1. Topographic Mapping:
   One of the most common uses of photogrammetry is creating detailed topographic maps. These maps display natural and man-made features such as hills, valleys, rivers, and buildings. Surveyors use these maps for planning construction, road alignment, and land development.
2. Digital Elevation Models (DEMs):
   Photogrammetry helps generate DEMs which show the elevation of land surfaces. DEMs are important in watershed management, flood risk assessment, and slope stability analysis in hilly areas.
3. Land Use and Land Cover Mapping:
   Aerial photos provide a large-scale view of land patterns. Surveyors analyze these images to classify different land types like forests, agricultural land, urban areas, and water bodies. This is useful for city planning and environmental monitoring.
4. Volume Estimation in Construction and Mining:
   Photogrammetry is used to calculate the volume of earthworks, stockpiles, or mining pits. By comparing images taken before and after excavation, engineers can accurately estimate the volume of material moved.
5. Monitoring Infrastructure Projects:
   Large infrastructure projects such as highways, railways, and dams are monitored using aerial photogrammetry. Regular image capturing allows progress tracking, identifying deviations, and ensuring that work is proceeding as per plan.
6. 3D City Modeling:
   In urban development, photogrammetry is used to build realistic 3D models of cities. These models help in designing buildings, understanding sunlight impact, and improving urban aesthetics.
7. Disaster Management and Planning:
   After events like floods, earthquakes, or landslides, photogrammetry helps quickly assess the damage and plan relief actions. It offers a fast way to map affected areas and support rescue operations.
8. Cadastral Surveying:
   Property boundaries and land records are mapped accurately with photogrammetry. It is especially useful in updating land records in remote or large areas where traditional methods are difficult.

Conclusion:

Photogrammetry in surveying is a powerful technique that saves time, increases accuracy, and provides valuable data for civil engineering applications. From topographic mapping to volume calculation and project monitoring, its uses are widespread and highly beneficial in modern surveying practices.