5.0. Unit Summary

This unit covers various aspects of photogrammetry. Various types of photographs and associated technical term used in photogrammetry are defined.

This section serves as an overview of photogrammetry, a technique used for obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images. The text indicates that it will detail different types of photographs relevant to photogrammetry and define the technical terms associated with these types.

Imagine taking pictures of your garden from different angles to capture its dimensions and layout. Each picture gives you a view that contributes to understanding the entire garden, similar to how various photographs in photogrammetry help create a detailed map of a terrain.

Concept of scale and relief displacement is explained. Relationships have been established to determine the scale of the photograph as well as relief displacement.

The unit explains that 'scale' refers to the relationship between distance on a photograph and the corresponding distance on the ground. 'Relief displacement' is the apparent movement of objects in a photograph due to elevation differences. The relationships derived help users determine the scale variations when photographs are taken from different heights.

Imagine you are looking at a picture of a mountain. The foreground objects appear larger than those in the background, which might be further away and smaller. This is similar to the concept of relief displacement in photographs taken from aerial views.

The principle of stereoscopy and use of stereoscope are covered.

This chunk discusses stereoscopy, which is a technique for creating or enhancing the illusion of depth in an image. A stereoscope allows the viewer to see two images taken from slightly different angles, enabling the brain to perceive depth. This principle is crucial in photogrammetry to interpret terrains accurately.

Think of how your two eyes work together to perceive depth in the world around you. A stereoscope mimics this function, helping you understand terrain relief as if you were actually there observing it.

Aerial triangulation plays an important role for providing horizontal as well as vertical controls from several aerial photographs; and therefore it has been described.

Aerial triangulation is a process used in photogrammetry to establish horizontal and vertical controls, helping to accurately construct three-dimensional models from a series of overlapping photographs taken from an aerial perspective. This ensures that all photographs are aligned and mapped correctly relative to each other.

Consider a puzzle where each piece represents a photograph of the landscape. Aerial triangulation is similar to figuring out how all the pieces fit together to represent the entire image correctly and accurately.

The use of digital aerial photographs which can be employed for large number of applications, including creation of DEM, DSM etc.

The unit highlights the importance of digital aerial photographs in modern applications such as creating Digital Elevation Models (DEM) and Digital Surface Models (DSM). These models are essential for various fields such as urban planning, transportation, environmental monitoring, and geology.

Imagine using Google Earth to explore terrains or cities from above. The digital photographs behind the scenes use similar principles from photogrammetry to create detailed 3D models you can navigate through.

At the end, some photogrammetric software are also given.

The section concludes by mentioning various types of photogrammetric software that assist professionals in analyzing aerial images, processing data, and integrating output for mapping purposes. These tools automate many aspects of photogrammetry, improving speed and accuracy in workflows.

It’s like using different apps on your phone to edit photos: some might enhance clarity, while others stitch images together. Similarly, photogrammetric software helps craft detailed maps and models from aerial imagery.

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