Satellite remote sensing imagery is a 2-dimensional (2D)
describing an object from view. Satellite remote sensing imagery depicts part
of the Earth's surface that look of a room.
1 Digital
and Analog image
The image can take the form of analog or
digital. For example, aerial image of analog in the form of a film with a
chemical process to get imagery, satellite imagery was obtained from sensors
and electronic diporses digitally.
Satellite imagery is printed or hardcopy form may also be referred to as
image/analog data.
Remote Sensing Data are not merely as an
image, but the image data is stored in a regular grid format commonly referred
to as raster data that consists of a line (row) and column (column). One of the
smallest element (Figure 7) is named as a pixel (picture element). For each
pixel has information coordinates (row and column) and spectral values are
converted in the form of numbers, commonly referred to as DN (Digital Number).
1 Pixel
Each pixel represents the area of the surface of the Earth with the
intensity and location of addresses in the form of 2-dimensional. Intensity
values describing the size of the physical quantity which is the reflection of
solar radiation emission or from an object with a specific wavelength that is
received by the sensor. As mentioned earlier, the intensity of the pixel values
are stored as digital (DN (Digital Number)). DN is stored in bits by a
specified amount.
| Figure 7. Satellite imagery Data with spectral value assets |
Remote
sensing data quality on the main system characteristics are determined by the
sensor platform.
Image:
Landsat satellite image Data with spectral TM5 owns.
|
Characteristics
of the system are usually indicated on sensor platforms:
1. Spectral radiometric resolution or
This resolution is based on each part
of the electromagnetic spectrum that is measured and the difference in energy
is observed. As an example: Landsat 7 ETM + has 9 channels/band, band 5 and
SPOT5 using IKONOS II using 5 band.
2. Spatial Resolution
Spatial resolution is based on the
smallest unit a measured object, indicating a minimum size of objects. For
example the size of the per pixel to 5 m x 5 m Panchromatic SPOT5 and 2.5 m x
2.5; Multispektral 10 m x 10 m and Landsat 7 ETM Panchromatic + 15 m x 15 m; 30
m x 30 m Multispektral Thermal A and B 60 m x60m; as well as Panchromatic
IKONOS II 1 m x 1 m, 4 m x 4 m Multispektral.
Image: comparison of spatial
resolution satellite images Landsat MSS, Landsat 5 m 30 m 20 m TM5, SPOT4 and
SPOT4 Pan 10 m. Landsat satellite image Data with spectral TM5 owns.
3. Temporal
Resolution (Repetition Of The Recording)
Temporal
resolution (Revisit time) is the time loop recording data retrieval or on
positions of the same object. Landsat 7 ETM + data retrieval or recording done
in the position of an object on the same day, IKONOS setiap16 II for 4 days to
an upright position and each day can do the recording for its ability to
perekeman in obliq position (sideways).
|