Lecture 4 Flashcards
(54 cards)
What is the wavelength range of visible light used in true color images?
400-700 nanometers (nm)
What are the three bands used in true-color images?
Red (620-750 nm), Green (495-570 nm), Blue (450-495 nm)
What does a false color image represent?
Non-visible wavelengths (e.g., NIR) are shown using visible color assignments.
What wavelengths are commonly used in false color images?
Near-infrared (700-1000 nm), Red, Green (visible and near-visible bands)
Why are false color images used?
To highlight features like vegetation health, water stress, or heat not visible in true color
How does healthy vegetation appear in a common false-color image (e.g., CIR)?
Bright red due to high NIR reflectance
What is an orthophoto?
A geometrically corrected aerial image with a uniform scale
What is a Digital Elevation Model (DEM)?
A 3D raster representation of ground surface elevation
What type of data does an orthophoto provide?
Photographic/visual information
What type of data does a DEM provide?
Elevation/topographic data
Can an orthophoto be used for measurement?
Yes, because it is orthorectified and free of distortion
Is a DEM a photo or a numerical dataset?
A numerical dataset
Why is photogrammetry used after a natural disaster?
To assess damage quickly in inaccessible or unsafe areas
How is photogrammetry used in archaeology?
For 3D documentation without damaging fragile sites
Why is photogrammetry preferred for tall structure inspections?
It avoids physical danger by using drones to collect data
How does photogrammetry assist in forensic investigations?
It reconstructs accident/crime scenes accurately and quickly
Why use photogrammetry in environmental monitoring?
To track terrain changes like erosion or deforestation over time
Question
Answer
What is the wavelength range of visible light used in true color images?
400-700 nanometers (nm)
What are the three bands used in true-color images?
Red (620-750 nm), Green (495-570 nm), Blue (450-495 nm)
What does a false color image represent?
Non-visible wavelengths (e.g., NIR) are shown using visible color assignments.
What wavelengths are commonly used in false color images?
Near-infrared (700-1000 nm), Red, Green (visible and near-visible bands)
Why are false color images used?
To highlight features like vegetation health, water stress, or heat not visible in true color
