Jawaharlal Nehru Technological University Hyderabad B.Tech III GEOINFORMATICS Previous Question Paper (November/December - 2020 - R16)

Terrestrial photography involves taking photographs from ground-based stations, typically using phototheodolites. Its main advantages include:

• Cost-effectiveness: It eliminates the need for expensive aircraft or satellite platforms for data acquisition.
• High Resolution: Since the camera is closer to the object, it captures fine details that may be lost in aerial imagery.
• Flexibility: Operations can be conducted under various weather conditions that might prevent aerial missions, and the setup is easily portable.
• Precision: It is highly effective for large-scale mapping of vertical structures like building facades or cliffs.

The primary disadvantages are:

• Limited Coverage: The field of view is restricted by ground-level obstructions, making it unsuitable for large-area mapping.
• Occlusion: Objects are frequently hidden behind foreground features, leading to significant blind spots.
• Geometric Constraints: The perspective is oblique, which complicates the process of orthorectification and planimetric mapping compared to nadir aerial views.

Small format aerial photography (SFAP) refers to the use of non-metric, small-format cameras (typically 35mm or digital SLR cameras) mounted on light aircraft, UAVs, or kites to capture aerial imagery. Unlike professional metric cameras, these systems are lightweight and highly accessible.

Key characteristics and applications include:

• Equipment: It utilizes consumer-grade cameras with smaller sensor sizes, which are significantly cheaper and easier to operate than large-format photogrammetric cameras.
• Low Altitude: SFAP is typically conducted at low altitudes, providing extremely high spatial resolution, often at the centimeter level.
• Rapid Deployment: Due to the portability of the equipment, it is ideal for emergency response, localized environmental monitoring, and small-scale site surveys where rapid data acquisition is required.
• Limitations: Because the cameras are non-metric, they lack internal calibration data (such as precise focal length and lens distortion parameters), requiring advanced software-based self-calibration techniques to process the imagery into accurate maps.
• Applications: It is widely used in precision agriculture, monitoring soil erosion, archaeological site documentation, and small-scale infrastructure inspections.