Photogrammetry Course Quiz

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Questions and Answers

Which platform is typically used for capturing large areas?

Terrestrial Cameras

Satellite Imagery

RPAS (Drones)

Manned Aircraft (correct)

Which of the following cameras has the highest resolution?

UltraCam Eagle

Leica CityMapper-2

Phase One PAS 880 (correct)

Leica DMC-4

What type of images are not covered in this course?

Ultra High Resolution Images

Terrestrial Images

Satellite Images (correct)

Drones

Which camera is known for being used in close-range photogrammetry?

DJI The Zenmuse P1 Signup and view all the answers

What is the definition of 'Sensor Field of View'?

The angle corresponding to each side of the frame Signup and view all the answers

What is a significant limitation of photogrammetry addressed in the course?

Dependence on ground control points Signup and view all the answers

What is the primary benefit of using data tiles in large data sets?

They divide data into manageable sections for visualization. Signup and view all the answers

Which compression method cannot be recovered after being compressed?

Lossy compression Signup and view all the answers

Which formats mentioned are noted for using lossless compression?

MrSid and ECW Signup and view all the answers

What mathematical relationship helps correct relief distances on a map?

h_A = H * r_a Signup and view all the answers

How does relief displacement behave with radial distance?

It increases with increasing radial distance. Signup and view all the answers

What does the term 'parallax' refer to in imaging?

The apparent displacement of an object from different viewpoints. Signup and view all the answers

Which of the following describes a common use of lossless compression formats?

For storing high-resolution images without losing detail. Signup and view all the answers

What is the formula for calculating parallax?

Parallax = d1 - d2 Signup and view all the answers

What is the relationship established by the collinearity model?

It establishes a connection between exposure center, image object point, and object point. Signup and view all the answers

How does parallax behave relative to the height of an object?

Parallax increases as the object height increases. Signup and view all the answers

What is the primary purpose of the coplanarity model in photogrammetry?

To relate a set of points in object space to their projection in image space. Signup and view all the answers

What does the parallax formula allow you to calculate?

The object height given flight height, focal length, and base distance. Signup and view all the answers

What is the consequence of two images being required for parallax measurement?

It allows for the calculation of depth information. Signup and view all the answers

Which of the following parameters is NOT part of the exterior orientation parameters (EOP)?

Focal length Signup and view all the answers

What does the exposure center refer to in the context of the collinearity condition?

The location of the camera at the moment of exposure. Signup and view all the answers

How many known ground control points are needed to derive the exterior orientation parameters?

Three Signup and view all the answers

In the context of the collinearity condition, what does the term 'object point' refer to?

The exact location of a point on the object being measured. Signup and view all the answers

Which rotational parameter is associated with rotation around the z-axis?

kappa (κ) Signup and view all the answers

What is a key characteristic of passive sensors?

They detect incoming energy from the environment. Signup and view all the answers

What type of resolution is measured in bits?

Radiometric Resolution Signup and view all the answers

Which of the following describes the nadir point?

The point where the lens center intersects the image plane. Signup and view all the answers

What factor does the spatial resolution depend on?

The altitude at which the sensor operates. Signup and view all the answers

What is the relationship between overlap and the imagery captured by drones?

Drones typically require more overlap compared to aerial imagery. Signup and view all the answers

What distinguishes active sensors from passive sensors?

Active sensors collect reflected energy, while passive do not. Signup and view all the answers

Geometric distortions in images can be minimized by using which method?

Calibration of the sensor. Signup and view all the answers

What does spectral resolution measure?

The ability to detect different spectral bands. Signup and view all the answers

Which resolution concerns the frequency of image acquisition for the same area?

Temporal Resolution Signup and view all the answers

What is the inter-ocular distance typically found in humans?

7 cm Signup and view all the answers

What does the term 'geometric center of the photo' refer to?

Principal Point Signup and view all the answers

Which of the following is NOT a type of geometric distortion?

Color saturation Signup and view all the answers

What does Otto Von-Gruber’s discovery regarding aligning points in a stereo model suggest?

Light rays will intersect if 6 points are aligned. Signup and view all the answers

What is a common use of data pyramids?

To reduce data size and enable generalization. Signup and view all the answers

What is the primary purpose of the Inertial Measurement Unit (IMU) in relation to stereoscopic vision?

To monitor aircraft roll, pitch, and yaw. Signup and view all the answers

A pocket stereoscope primarily requires what for its functionality?

Two aligned photos with anaglyph colors. Signup and view all the answers

Which type of resolution would be most relevant for assessing color levels in an image?

Radiometric Resolution Signup and view all the answers

What does the term 'Earth curvature' pertain to when discussing photo distortions?

Distortion caused by the Earth's round shape. Signup and view all the answers

What technology does the softcopy/digital photogrammetry workstation primarily rely on?

Digital images and computerized systems. Signup and view all the answers

Which of the following is NOT a product created by a stereo workstation?

Live-action video streams Signup and view all the answers

What is the primary function of colored filters in an anaglyph?

To create two distinct images that can be viewed with special glasses. Signup and view all the answers

Which of the following viewing devices is associated with DAT/EM Summit?

Stereo viewer Signup and view all the answers

What is the primary function of the Stereo Workstation?

To visualize the stereo model and compute geometry Signup and view all the answers

Which feature is NOT a function of the DAT/EM Keypad?

Performing 3D digitizing directly Signup and view all the answers

What differentiates Large Scale Compilation from Medium Scale Compilation?

Large Scale includes detailed elements like curbs and individual trees, while Medium Scale covers broader areas like bus routes. Signup and view all the answers

Which lens characteristic is recommended for terrestrial photogrammetry?

Wide angle lens Signup and view all the answers

To achieve accurate terrestrial photogrammetry, how many control points are recommended per side?

At least four control points Signup and view all the answers

What is the recommended base-to-distance ratio for architectural photogrammetry?

1:4 to 1:15 Signup and view all the answers

What is a key characteristic of Building Information Modeling (BIM)?

It serves as a collaborative design process visualizing both physical and functional aspects. Signup and view all the answers

What does a Digital Twin encompass beyond individual buildings?

Community-wide factors such as weather and occupancy Signup and view all the answers

Which factors do NOT affect optimum flying height in flight planning?

The weather conditions of the area Signup and view all the answers

During orthorectification, by what factor does the pixel size increase due to resampling processes?

1.2 Signup and view all the answers

Study Notes

Course Review Modules

Module 1: Introduction to Photogrammetry & Platforms
Module 2: Models, Orientation & Stereoscopic Vision
Module 3: Planimetric Capture & 3D Digitizing
Module 4: Terrestrial Photogrammetry & 3D Models
Module 5: Flight Planning
Module 6: Photo Acquisition, Processing and ABGPS
Module 7: Orthophotos
Module 8: Data Visualization and Mapping
Module 9: Image Interpretation and Analysis
Module 10: Digital Elevation Model(s)
Module 11: Photogrammetry Applications, Limitations & Review
Module 12: RPAS Applications - Guest lecture Dec 3

Key Concepts Learned

Platforms: Manned Aircraft (large areas), RPAS (Drones) (small areas), Terrestrial (close range). Satellite images are not covered in this course.
Sensors/Frames: Large/medium format cameras (e.g., UltraCam Eagle, Leica DMC-4, Leica CityMapper) and close-range cameras (e.g., Phase One P5, DJI The Zenmuse P1, DJI ZENMUSE L2, Sony RX1R ii). Sensor field of view vs instantaneous field of view—sensor FOV is the angle corresponding to each side of the frame, and instantaneous FOV is the angle corresponding to a single pixel. Each sensor/camera frame is usually rectangular.
Sensors/Frames - Nadir and Oblique Images: Nadir is a vertical/nadir image where the camera's optical axis is pointing straight down. Oblique image is where the camera's optical axis is at an angle.
Sensors/Frames - Waves and Surfaces Interaction: Transmission, reflection, refraction, diffraction, absorption, and scattering related to how light waves interact with surfaces. A spectral reflectance curve is included, showing reflectance percentages (%) against wavelength (micrometers), with examples of dry soil, healthy vegetation and clear water.
Passive vs Active Sensors: Passive sensors (covered in course) don't emit energy (e.g., optical/infrared). Active sensors (not covered) emit energy (e.g., LiDAR/RADAR).
Geometric Distortions: Lens distortion, terrain/relief displacement, camera optical axis/tip and tilt, atmosphere refraction, and earth curvature. Correcting for these requires calibration or models. Image motion is another distortion.
Resolutions: Spectral (ability to detect different spectral bands: black and white (panchromatic), RGB, multispectral/RGB/NIR, hyperspectral), radiometric (ability to detect small differences in energy), and spatial (ability to detect small ground details, from 2cm and up).
Stereo Pairs, Overlap and Geometry: Showing side lap, front lap, and overlap of aerial photos and drones (60/30 and 80/80, etc.).
Photo Scale: The relation between flying height above ground (AGL), focal length of the camera, and ground pixel size. Includes calculations for average scale. Ground pixel size can vary based on topography, meaning it varies across an image.
Photo Frame and Scale: including terms like principal point, fiducial mark, fiducial center, nadir point, principal point from the photo, etc.
Data types & Presentations (Data Pyramids & Tiles): Primarily for raster data, designed to manage very large datasets in a way that helps with displaying different resolutions in a hierarchical way.
Compression Effect: Lossy (compressed beyond recovery), Lossless (compressed but recoverable).
Mathematical Models: Includes the collinearity model and the coplanarity model for relationships between object space and image space. Rotation around photo x, y, and z axes are also included.
Relief Displacement: Importance of knowing object height to correct distances from relief distance.
Parallax: Apparent displacement of an object as seen from two different points (different points on the principal point).
Interior, relative, and absolute orientations: Interior orientation (relationship between sensor and image coordinate systems, x,y of PP, focal length), relative orientation (aligns one photo to another), and absolute orientation (oriente photo to a ground coordinate system). Common methods, like RTK, PPK, and PPP, are included.
Stereoscopic Vision: Overview of basic concepts including interocular distance, stereo pairs, misalignment and aligned stereo models and von Gruber points. Includes pocket stereoscopes and anaglyphs, and examples of software workstations used.
Photogrammetry and Mapping Applications: Large and medium scale compilation of different types of maps (roads, neighborhoods, trees etc.) are included here.
Cameras, Properties: Includes fixed focal length, fixed distance for photogrammetry, high-quality lens, large sensor, and precise tolerances.
Controls for Terrestrial Photogrammetry: Control points, scale bars, etc.
Base-to-Distance Ratio: Ratio between the base and distance relevant to stereo vision (1:4 to 1:15).
BIM & Digital Twin: Overview of BIM (collaborative design & build process that visualizes physical and functional aspects of a building) and digital twin (a virtual replica of physical entities).
Flight Planning: Design of flight path & height, speed, covering area of interest, meeting specifications, and cost-effectiveness.
Optimum Flying Height: Factors including map/orthophoto scale, contour factor and interval, GSD, pixel size, image resolution, topography, air traffic restrictions, and accuracy.
Pixel Size - Orthorectification Factor: Importance of the resampling process in orthorectification that increases the pixel size by a factor of 1.2.
OFH - Contour Factor and Interval: Values typically ranging from 1800 to 2400 (dimensionless) and used to determine the flying height.
OFH - GSD: Finding the Ground Sampling Distance, relationship to flying height and spatial resolution, and the meaning of a given GSD. Also, relative accuracy, relationship and formula.
OFH - Image Resolution: What's the smallest object that needs to be clearly visible? Is a single pixel sufficient? How many pixels are required to positively detect an object?
Seasonal Considerations: Springtime (few leaves) is ideal for maximum land exposure, while summer (in full bloom) provides minimum land exposure. Other weather factors like temperature, precipitation and wind.
Sun Angle Considerations: Low sun angle creates shadows. High sun angle can lead to overexposure. Important range of sun angles.
Execution: Where Can I Fly?: Regulations for operation within different airspace types.
Execution: Safety: Safety equipment and procedures (pad, anemometer, safety cones, etc.) for RPAS operations, and that flying drones can be dangerous.
Metric Cameras: Designed for photogrammetry, fixed lens focused on infinity, no zoom, high-quality lens, little or no distortion.
Non-Metric Cameras: Not designed for photogrammetry, use zoom lenses, variable focus, unknown interior orientation parameters (focal length and principal point), lens distortion, and measurement errors.
Camera Settings: Aperture, shutter speed, and ISO, all related to exposure and brightness.
Motion Blur: Understanding motion blur, how it's related to flying speed, flying height and shutter speed, and what is the GSD.
Processing: Differential GPS vs PPP: Differential GPS: needs a base station within 25-50 km of the rover. PPP does not need one. Both are accurate, but PPP is becoming more common as it matures.
Overview: Standard orthos use DEMs/DTMs which only corrects ground elevations, true orthos correct elevated features like buildings and trees, DSM is available from LiDAR technology.
GCP Processing (AT/BBA): GCPs (Ground Control Points) are used for processing and their importance and properties regarding sizes and types.
Orthorectification: Transformation from radial view to an orthogonal view, new pixel positions (re-projection), which considers control points, polynomial rectification, and differential rectification.
Quality Control: Checks before delivery including geographic extent, projection and coordinate system, format, naming convention, tiling, and metadata.
Image Enhancement: Covers histogram, linear stretch, percentage stretch, histogram matching, spatial filtering, noise reduction, deblurring, Wiener and wavelet filters, and reflectance calibration.
Band Combinations: Useful relationships between reflectance and features like leaf pigments, leaf structure, water content, leaf biochemicals, senescence, and soil. Wavelength ranges are covered.
Thermal Imaging and Forest Fire: Unique aspects of thermal bands, emitted heat, and example (Town of Lytton).
Raster 2d, 2.5d, and 3d: Covers overview of data types.
Tiles and Pyramids: Efficient way to manage and visualize large raster datasets based on hierarchical tiling schemes for resolutions, size and data.
Manual/Visual vs Digital Interpretation: Comparison of methods; manual methods require no special equipment, but digital methods require specialized software and computers.
Visual Interpretation: How visual elements like tone, shape, size, etc. can make interpretation more difficult.
Computer Based Analysis & Interpretation: Computer-based methods like pixel based and object based classification (including supervised vs unsupervised).
Digital Terrain Models (DTMs): Representations of the Earth's surface, giving elevation data, types (DSM, DEM). Including different modeling methods (grid, TIN).
Interpolation Techniques: The methods used to estimate unknown points based on sample data points.
DTM/DEM Data Sources: Various methods for creating DTMs/DEMs such as land surveys, existing contours, photogrammetry, satellite imagery (including stereo), radar (active-sensor), and LiDAR.
Summary: All the concepts studied in the previous sections are summarized in a concise manner. Includes important applications, limitations and overall review.

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Test your knowledge on the concepts covered in Module 6 of the photogrammetry course. This quiz addresses topics such as sensor fields of view, digital elevation models, and various types of image compression. Challenge yourself to recall key definitions and applications within photogrammetry!

Photogrammetry Course Quiz - Module 6

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