Photogrammetry

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Questions and Answers

What primary factor drove the initial adoption of photogrammetry beyond France?

Increased artistic expression through photography.
Military need for small-scale maps. (correct)
Advancements in goniometer technology.
Demand for high resolution architectural models.

What was the defining characteristic of the phototheodolite that improved photogrammetry?

Integration of a camera with a goniometer. (correct)
Ability to capture color images on glass plates.
Automated image processing capabilities.
Use of balloons to capture high-altitude images.

What advancement directly enabled the creation of the first aerial photograph?

Use of glass plate negatives. (correct)
Development of digital image sensors.
Invention of lightweight drones.
Application of kites and kite trains.

What was the main advantage of using phototheodolites over standard cameras for early photogrammetry?

They facilitated inclined pictures and greater precision. (A) Signup and view all the answers

In what context were balloons initially used for military purposes in the U.S. Army?

For aerial reconnaissance during the American Civil War. (C) Signup and view all the answers

How did the requirements of cartography and architecture influence the development of photogrammetry?

They created a demand for improved accuracy and precision in photogrammetric techniques. (A) Signup and view all the answers

What role did Albrecht Meydenbauer play in the history of photogrammetry?

He is considered the father of architectural photogrammetry. (D) Signup and view all the answers

What key technological advancement enabled Gasper Felix Tournachon (Nadar) to capture the first aerial photo of Paris?

Combining photography with balloon technology. (C) Signup and view all the answers

What is the primary advantage of using digital photogrammetric workstations compared to classical photogrammetry?

Digital workstations incorporate automatic procedures, increasing efficiency, whereas classical photogrammetry requires individual point collimation and identification by an operator. (D) Signup and view all the answers

How does Structure from Motion (SfM) contribute to modern photogrammetry?

SfM automates the creation of point clouds, which can be used to generate meshes (surfaces). (C) Signup and view all the answers

What is the fundamental principle behind anaglyph 3D imaging?

Encoding each eye's image using filters of different colors, typically red and cyan. (C) Signup and view all the answers

What is an anaglyph?

A stereoscopic 3D effect achieved using color filters. (D) Signup and view all the answers

A researcher is studying the structural changes in a historical building using photogrammetry. Which photogrammetry type would be most suitable?

Close-range Photogrammetry (B) Signup and view all the answers

What is the primary way to acquire digital imagery for digital photogrammetry?

Directly acquiring digital images or scanning film-based images to convert them digitally. (C) Signup and view all the answers

An urban planner needs to create a detailed 3D model of a city for urban analysis. Which photogrammetric approach would be the MOST efficient for capturing the required data?

Aerial photogrammetry using drones or aircraft. (B) Signup and view all the answers

What is the purpose of the red/cyan glasses used in conjunction with anaglyph images?

Filter the images to encode each eye's view, creating a 3D effect. (A) Signup and view all the answers

In Structure from Motion (SfM) and Multi-View Stereo (MVS) software, what is the primary goal of the 'Matching' procedure?

To automatically locate corresponding (homologous) points across multiple digital images. (D) Signup and view all the answers

Which factor is LEAST critical when searching for a homologous entity on another image during the matching process in digital photogrammetry?

The stereoscopic setup of the images. (B) Signup and view all the answers

What is a key limitation of the 'Matching' procedure in SfM-MVS workflows?

Not all points in an image may have a corresponding homologous point in other images. (D) Signup and view all the answers

In an SfM-MVS workflow, what is the purpose of evaluating the quality of the matching process?

To quantify the accuracy and reliability of the identified homologous points. (C) Signup and view all the answers

How does Structure from Motion (SfM) differ from traditional stereophotogrammetry regarding image constraints?

SfM does not require a priori constraints on the geometry and nature of the images, unlike stereophotogrammetry. (B) Signup and view all the answers

In analogue photogrammetry, what type of system is primarily used for orientation and plotting?

A precise mechanical-optical system (A) Signup and view all the answers

Which photogrammetry approach uses images on photographic support but performs orientation and plotting via a computer system?

Analytical photogrammetry (D) Signup and view all the answers

What defines digital photogrammetry in terms of image format and processing?

Images are supplied in digital format, with many processes automated. (B) Signup and view all the answers

How does an analogue stereoplotter recreate the situation at the photo acquisition stage?

Using a complex mechanical-optical system (D) Signup and view all the answers

If you needed to create a 3D model of a historical site using photographs and wanted the most automated processing, which method would be most suitable?

Digital photogrammetry, for its automated processing capabilities. (D) Signup and view all the answers

What characteristic of analytical photogrammetry distinguishes it from analogue photogrammetry?

It uses computer systems for orientation and plotting. (B) Signup and view all the answers

In the context of photogrammetry, what is the primary role of a stereoplotter?

To allow the operator to view a stereo model and derive measurements (A) Signup and view all the answers

Why might a surveyor choose analytical photogrammetry over analogue photogrammetry?

To improve accuracy and efficiency using computational methods (D) Signup and view all the answers

What is a key advantage of digital photogrammetry over both analogue and analytical methods?

Enhanced automation and reduced need for manual intervention (B) Signup and view all the answers

Which instrument uses a binocular eyepiece to view left and right images separately, creating a stereoscopic effect?

A stereoplotter (C) Signup and view all the answers

What is the primary role of homologous points in Structure from Motion (SfM)?

To automatically identify matching features across multiple images. (B) Signup and view all the answers

Why is the automatic determination of camera interior and exterior orientation important in SfM?

It enables the software to accurately reconstruct the 3D structure from the images. (C) Signup and view all the answers

In SfM, what does a high degree of probability in the pairing of homologous points between two images indicate?

The two images have a strong geometric relationship and are likely to contribute significantly to the 3D reconstruction. (A) Signup and view all the answers

What is the significance of analyzing a large number of images (e.g., 110) in the SfM process?

It increases the accuracy and robustness of the 3D reconstruction by providing more data and redundancy. (A) Signup and view all the answers

How does the density of homologous points affect the quality of the resulting 3D point model in SfM?

Higher density of homologous points leads to a more detailed and accurate 3D point model. (A) Signup and view all the answers

Which of the following best describes the key difference between an orthophoto and a rectified image?

An orthophoto corrects for perspective distortions using object surface knowledge, while a rectified image assumes a planar surface. (C) Signup and view all the answers

In the context of photogrammetry, what does 'interior orientation' primarily address?

Defining the internal characteristics of the camera, such as focal length and lens distortion. (B) Signup and view all the answers

What is the primary purpose of using Ground Control Points (GCPs) in photogrammetry?

To provide known X, Y, Z coordinates for georeferencing and accurately orienting the 3D model. (D) Signup and view all the answers

What geometric characteristic is preserved in a central projection, as used in photography?

Straight lines remain straight. (A) Signup and view all the answers

In the collinearity equations, what do the parameters X0, Y0, and Z0 represent?

The coordinates of the projection center in the object space. (C) Signup and view all the answers

Which of the following image products would be most suitable for accurately measuring building footprints in an urban area?

An orthophoto-mosaic. (C) Signup and view all the answers

What parameters are typically provided in a camera calibration certificate?

Focal length and lens distortion parameters. (C) Signup and view all the answers

How does flight height (H) relative to the terrain affect the photoscale (s)?

Photoscale decreases as flight height increases, assuming focal length is constant: $s = c/H$. (B) Signup and view all the answers

In the collinearity equations used in photogrammetry, what is the significance of the rotation matrix R (rij)?

It relates image coordinates to object space coordinates by accounting for the camera's orientation. (D) Signup and view all the answers

Why is exterior orientation necessary in photogrammetry?

To determine the position and orientation of the camera at the time of exposure. (C) Signup and view all the answers

Consider a scenario where you have imagery of a perfectly flat agricultural field. Which product would be most appropriate?

A rectified image (photoplane), because it's suitable for planar objects and simpler to produce. (C) Signup and view all the answers

In the equations provided, what does the variable 'c' represent?

The focal length of the camera. (A) Signup and view all the answers

A photogrammetry project requires high accuracy in areas with significant elevation changes. Which processing step is most critical to ensure that the final product meets the project's accuracy requirements?

Precise exterior orientation using a sufficient number of well-distributed Ground Control Points (GCPs). (B) Signup and view all the answers

What key assumption is made when using a rectified image (photoplane)?

The object being imaged is essentially planar. (D) Signup and view all the answers

How do the angles omega (ω), phi (φ), and kappa (κ) relate to the exterior orientation process?

They describe the rotational component of the camera's position in space. (B) Signup and view all the answers

Flashcards

Laussedat Experiments

Experiments starting in 1855 that contributed to photogrammetric studies in Italy.

Projection Analogue Plotting

A method of graphically plotting that uses analogue instruments and projected images to create maps.