Principal Point (PP): The point where the optical axis of the camera meets the photograph . In a perfectly aligned camera, it is near the geometric centre of the photo. Nadir Point (N): The point directly vertically below the camera lens at the moment the photograph is taken. Isocenter (I): The point located midway between the principal point and nadir point on a tilted aerial photograph. Photo Centre: Generally refers to the centre of the photograph ; it is often treated as the principal point in basic explanations. Fiducial Marks: Small reference marks fixed along the edges/corners of an aerial photograph . Lines joining opposite fiducial marks are used to determine the principal point . Flight Line: The path followed by the aircraft while taking a sequence of aerial photographs. Easy relationship: Camera → Optical axis → Principal Point Camera → Vertical/plumb line → Nadir Point PP ↔ Isocenter ↔ Nadir (Isocenter lies halfway betwee...
Geographical Models A model is a simplified representation of reality used to describe, explain, simulate, and predict geographical phenomena. Types Physical (Iconic) Models – Three-dimensional representations (e.g., globe, relief model). Conceptual Models – Diagrams or frameworks explaining geographical relationships. Mathematical (Quantitative) Models – Equations and statistical models for spatial analysis and prediction. Simulation Models – Computer-based models that simulate geographical processes (e.g., climate, flood, urban growth). Major Geographical Models Model Scholar Year Concept Johann Heinrich von Thünen Agricultural Land Use Model 1826 Land use varies with distance from the market. Walter Christaller Central Place Model 1933 Distribution of settlements and services. Ernest Burgess Concentric Zone M...