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4. Relief Displacement of a Vertical Photograph

The chapter discusses relief displacement and stereoscopy, emphasizing their significance in aerial photography and photogrammetry. It explains how relief displacement affects the accuracy of measurements on vertical photographs due to varying heights of objects, and the importance of stereoscopic modeling in providing depth perception through stereo-pairs. Lastly, it covers the essentials of aerial triangulation, highlighting its applications in mapping and surveying.

Sections

Relief Displacement of a Vertical Photograph

Relief displacement in vertical photographs alters the perceived position of objects based on their height, leading to inaccuracies in measurements.

4.10 Section Overview

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Stereoscopy

Stereoscopy is a technique for creating a 3D perception using stereo-pairs of images.

4.11 Section Overview

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4.11.1 Stereoscopic model

A stereoscopic model is created using a pair of stereo images to visualize depth perception, enabling the differentiation between objects in their spatial context.

4.11.2 Requirements of a stereoscopic vision

This section outlines the essential conditions needed to achieve stereoscopic vision for creating 3D models from stereo-pairs of photographs.

4.11.3 Stereoscopes

Stereoscopes are optical devices used to view stereo-pairs of images, enabling depth perception by presenting separate images to each eye, thereby creating a 3D model of a landscape or object.

4.11.3.1 Lens stereoscopes

Lens stereoscopes are optical devices used for 3D viewing of stereo-pairs of photographs, essential for photogrammetry.

4.11.3.2 Lens and mirror stereoscopes

This section explores lens and mirror stereoscopes, their construction, functionality, and applications in creating three-dimensional views of aerial photographs.

Determination of Height from Vertical Aerial Photographs

This section discusses the technique of determining the height of various objects from vertical aerial photographs using stereo-photographs and parallax measurements.

4.12 Section Overview

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4.12.1 Orienting a stereo-pair of photographs

This section discusses the process of orienting a stereo-pair of photographs to create a 3D model using stereoscopy.

4.12.2 Measurements by Parallax Bar

This section discusses the concept of parallax in aerial photography, explaining how relief displacement of objects affects their measurement in stereo-pairs.

4.12.3 Measurement of absolute parallax

The section details the concept of absolute parallax in aerial photography, emphasizing its computation as the difference in distances from principal points.

4.12.4 Height determination

This section discusses methods for determining the height of objects using vertical aerial photographs, emphasizing the relationship between parallax measurements and elevation calculations.

Tilted Photographs

Tilted photographs are taken with the camera at an angle greater than 30 degrees from vertical, resulting in distortions that prohibit their direct use for mapping and measurement.

4.13 Section Overview

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4.13.1 Scale of a tilted photograph

The scale of a tilted photograph varies depending on the tilt angle and elevation of objects, influencing measurement accuracy.

4.13.2 Tilt displacement

Tilt displacement refers to the variation in images captured on tilted aerial photographs, affecting their apparent position and measurements.

Aerial Triangulation

Aerial triangulation is a method in photogrammetry used to determine 3D coordinates from stereo-photographs, minimizing field work.

4.14 Section Overview

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4.14.1 Types of aerial triangulation

This section outlines the two main types of aerial triangulation - radial triangulation and block triangulation, explaining their methodologies and applications in photogrammetry.

4.14.1.1 Radial Triangulation

Radial triangulation is a method used to determine 3D coordinates from aerial photographs while minimizing fieldwork.

Learning Objectives

  • Relief displacement occurs on vertical photographs due to height variations of objects, affecting their true plan positions.

  • Stereoscopy allows the creation of three-dimensional models from two-dimensional photographs, enhancing depth perception.

  • Aerial triangulation helps determine 3D coordinates from stereo-photographs, reducing the need for extensive fieldwork.

Key Concepts

Relief Displacement

The horizontal displacement of objects in a vertical aerial photograph from their true geographic positions due to varying heights.

Stereoscopy

A technique that creates a 3D model from two images by utilizing depth perception and parallax principles.

Aerial Triangulation

A method used to determine the 3D coordinates of points by analyzing a series of stereo-photographs.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting

1 more question available

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