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Sensor Resolution in Remote Sensing

What is Remote Sensing Resolution?

Resolution is a broad term commonly used in Remote Sensing.

The Resolution is several pixels display on a display device, or area on the ground that a pixel represents in an image file.

4 distinct types of resolution must be considered:

  1. Spectral—specific wavelength intervals that a sensor can record
  2. Spatial—area on the ground represented by each pixel
  3. Radiometric—number of possible data file values in each band
  4. Temporal—how often a sensor obtains imagery of a particular area

Comparison of Landsat Sensors

ResolutionsThematic Mapper (TM) Landsat 4 and 5Enhanced Thematic Mapper Plus (ETM+) Landsat 7Multispectral Scanner (MSS) Landsat 1-5
Spectral Resolution (μm)1. 0.45-0.52 (B)
2. 0.52-0.60 (G)
3. 0.63-0.69 (R)
4. 0.76-0.90 (NIR)
5. 1.55-1.75 (MIR)
6. 2.08-2.35 (MIR) 7. 10.4-12.5 (TIR)
1. 0.45-0.52
2. 0.53-0.61
3. 0.63-0.69
4. 0.78-0.90
5. 1.55-1.75
6. 2.09-2.35
7. 10.4-12.5
8. 0.52-0.90 (Pan)
0.5-0.6 (green)
0.6-0.7 (red)
0.7-0.8 (NIR)
0.8-1.1 (IR)
Spatial Resolution (meter)30 x 30 120 x 120 (TIR)15 x 15 (Pan) 30 x 30 60 x 60 (TIR)79 x 79
Spatial coverage (km)185 x 185183 x 170185 x 185
Temporal Resolution (days) 161618
Altitude (km)705705915 (Landsat 1,2,3)

Types of Resolution in Remote Sensing

Spectral Resolution in Remote Sensing

Spectral resolution refers to the specific wavelength intervals in the Electromagnetic spectrum that a sensor can record (Simonett et al., 1983). For example, band 1 of the Landsat TM sensor records energy between 0.45 and 0.52 μm in the visible part of the spectrum.

Wide intervals in the electromagnetic spectrum are referred to as coarse spectral resolution, and narrow intervals are referred to as fine spectral resolution. For example, the SPOT panchromatic sensor is considered to have coarse spectral resolution because it records EMR between 0.51 and 0.73 μm.

On the other hand, band 3 of the Landsat TM sensor has a fine spectral resolution because it records EMR between 0.63 and 0.69 μm (Jensen, 1996).

Spatial Resolution in Remote Sensing

Spatial resolution is a measure of the smallest object that can be resolved by the sensor, or the area on the ground represented by each pixel (Simonett et al, 1983). The finer the resolution, the lower the number. For instance, a spatial resolution of 79 meters is coarser than a spatial resolution of 10 meters.

Seale

Large-scale in remote sensing refers to imagery in which each pixel represents a small area on the ground, such as SPOT data, with a spatial resolution of 10m or 20 m. Small scale refers to imagery in which each pixel represents a large area on the ground, such as Advanced Very High Resolution Radiometer (AVHRR) data, with a spatial resolution of 1.1 km.

IFOV

Spatial resolution is also described as the Instantaneous Field of View (IFOV) of the sensor, although the IFOV is not always they same as the are represented by each pixel. The IFOV is a measure of the area viewed by a single detector in a given instant in time (Star and Estes, 1990).

For example, Landsat MSS data have an IFOV of 79 × 79 meters, but there is an overlap of
11.5 meters in each pass of the scanner, so the actual area represented by each pixel is 56.5 × 79 meters.

Radiometric Resolution in Remote Sensing

Radiometric resolution refers to the dynamic range, or number of possible data file values in each band. This is referred to by the number of bits into which the recorded energy is divided.

In 8-bit data, the data file values range from 0 to 255 for each pixel, but in 7-bit data, the data file values for each pixel range from 0 to 128.

The sensor measures the EMR in its range. The total intensity of the energy from 0 to the maximum amount of the sensor measures is broken down into 256 brightness values for 8-bit data, and 128 brightness values for 7-bit data.

Temporal Resolution in Remote Sensing

Temporal resolution refers to how often a sensor obtains imagery of a particular area. For example, the Landsat satellite can view the same area of the globe once every 16 days. On the other hand, SPOT can revisit the same area every three days.

Resolution of various satellites

Sl.No.SatelliteSensorTemporal resolutionSpectral resolutionSpatial resolution
1.NOAA-17 National Oceanic and Atmospheric AdministrationAVHRR-3
Advanced Very High Resolution Radiometer
2-14 times per day0.58-0.68(1), 0.73-1.00(2),
1.58-1.64
(3A day)
3.55 -3.93
(3B night)
10.3-11.3(4)
11.5-12.5(5)
1 Km X 1Km (at nadir)
6 Km X 2Km
(at limb)
2.LandsatMSS
Multispectral scanner
18 days0.5-0.6
0.6-0.7
0.7-0.8
0.8-1.1
79/82m
79/82m
79/82m
79/82m
79/82m
TM
The Thematic Mapper
18 days0.45-0.52(1)
0.52-0.60(2)
0.63-0.69(3)
0.76-0.90(4)
1.55-1.75(5)
10.4-12.5(6)
2.08-2.35(7)
30m
30m
30m
30m
30m
120m
30m
ETM+
Enhanced Thematic Mapper
16 daysAll TM bands + 0.50-0.90 (PAN)15m(PAN)
30m (band 1-5,7)
60m (band 6)
3.TerraASTER Advanced Spaceborne Thermal Emission and Reflectance Radiometer5 days (VNIR)VIS (BANDS 1-2), 0.56, 0.66,
NIR 0.81,
SWIR (4-9),
1.65, 2.17, 2.21, 2.26, 2.33, 2.40, TIR (bands 10-14) 8.3, 8.65, 9.10, 10.6, 11.3
15m(VNIR)
30m (SWIR)
90m(TIR)        
4.SPOT-5
Systeme Pour I ‘Observation de la Terre
2 X HRG (High resolution Geometric ) and HRS High Resolution Streoscopic2-3 days0.50-0.59
0.61-0.68
0.78-0.89 (NIR)
1.58-1.75 (SWIR)
0.48-0.70 (PAN)
10m, 5m (PAN)
5.Resourcesat 1LISS 4
Linear Imaging Self Scanning
5-24 days0.56,  0.65, 0.806m
6.IkonosOptical Sensor Assembly(OSA)1-3 days0.45-0.52(1),
0.52-0.60(2),
0.63-0.69(3),
0.76-0.90(4),
0.45-0.90 (PAN)
1m (PAN)
4m (bands 1-4)
7.EO-1 Earth ObservingCHRIS (Compact  High Resolution Image Spectrometer)Less than 1 week typically 2-3 days19 or 63 bands
410 nm-1050 nm
18m (full spatial resolution)
36(full spectral resolution)
8.EO-1Hyperion16 days220 bands30 m
9.Envisat-1ASAR35 daysC-band, 5.331 GHz30m-150m (depending on mode)
MERIS3 days1.25 nm to 25 nm
15m bands
300m (land)
1200m(ocean)
10.IRS (Indian Remote Sensing)-1A, 1B, 1C, 1D, P6LISS-III, LISS-IV24 days0.52-0.59µm
0.62-0.68 µm
0.77-0.86µm
1.55-1.70µm
0.5-0.75 µm
(Panchromatic)
23 m resolution (70m in mid IR)(LISS III ), 5.8 m(LISS-IV)
Panchromatic5 days5.8m
Wide Field Sensor (WiFS)3 days188m
11.Quick BirdPanchromatic Multispectral1-5 daysBlue
(450-520 nm)
Green
(520-600 nm)
Red
(630-690 nm)
Near IR
(760-900nm)
60-70cm (panchromatic sensor)
2.4m-2.8m (Multispectral)
12.   Cartosat I,IIPanchromatic4-5 days0.50-0.85µm2.5m, less than 1 meter

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