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Questions and Answers
What term describes the area of terrain covered by a single detector's field of view?
What term describes the area of terrain covered by a single detector's field of view?
What type of resolution is measured in bits and determines the brightness levels in an image?
What type of resolution is measured in bits and determines the brightness levels in an image?
How many spectral bands are used by the Landsat 7 ETM+ satellite?
How many spectral bands are used by the Landsat 7 ETM+ satellite?
Which resolution is primarily concerned with the discrimination of features and depends on sensor specifications?
Which resolution is primarily concerned with the discrimination of features and depends on sensor specifications?
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What is the effect of increasing the radiometric resolution on an image?
What is the effect of increasing the radiometric resolution on an image?
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Which of the following wavelengths corresponds to the NIR band of the Landsat 7 ETM+?
Which of the following wavelengths corresponds to the NIR band of the Landsat 7 ETM+?
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Which band from the Landsat 8-9 OLI has the highest spatial resolution?
Which band from the Landsat 8-9 OLI has the highest spatial resolution?
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In terms of image quality, what does the Ground Sample Distance (GSD) refer to?
In terms of image quality, what does the Ground Sample Distance (GSD) refer to?
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Study Notes
Spectrum Reflectance Curve/Signature
- Reflectance curves show how much light different surfaces reflect at different wavelengths.
- Different materials reflect light differently.
- Vegetation reflects more light in the near infrared wavelengths.
- Dry soil reflects more light in the visible and near infrared wavelengths.
- Water reflects less light overall, and more in the near infrared and shortwave infrared.
Image Resolution
- Image resolution determines image quality & applications.
- Three types of resolution exist: spatial, spectral, and radiometric.
Spatial Resolution
- Spatial resolution is the sensor's ability to distinguish features.
- Ground Sample Distance (GSD) and Field of View (FOV) describes spatial resolution.
- GSD is the distance on the ground represented by a pixel.
- FOV is the area on the ground encompassed by a detector's view.
- Pixel size is a synonym for IFOV.
Spectral Resolution
- Spectral resolution is the width of the wavelength bands a sensor can detect.
- Sensors detect light over a range of wavelengths (or bands)
- Different sensors have various bands with their own resolutions.
Radiometric Resolution
- Radiometric resolution refers to the sensor's sensitivity to variations in light intensity.
- Measured in bits
- 8-bit images have 256 brightness levels or gray levels.
- Higher radiometric resolution results in better detail and contrast.
Multispectral Images
- Multispectral images are collected at several wavelength bands (a spectrum).
- The number of bands depends on the sensor type.
- Landsat 7 ETM+ has 8 bands/spectra
- Landsat 8 and 9 OLI & TIRS have 10 bands/spectra
Landsat Bands (Specifics)
- Information about wavelengths, ranges, and resolution for various Landsat sensor bands is provided in a table format.
Image Processing
- Image processing methods improve remote sensing image usability.
- Images are often initially in a "digital number" (DN) format.
- DN images often contain atmospheric scattering & sensor errors.
- DN values are converted to reflectance to accurately represent the subject.
- Image calibration converts DN to radiance & reflectance.
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Description
Explore the principles of reflectance curves and image resolution in remote sensing. Learn how different surfaces reflect light and the importance of spatial, spectral, and radiometric resolution for image quality. This quiz covers essential concepts in understanding remote sensing data.
