540
16 Scientific Instrument Technology of Lunar Lander
Table 16.9 Calibration and special tests of morphology camera
Tests
Purpose
Flat fielding calibration
Camera dark current detection and relative radiation
calibration
Absolute radiation calibration
To establish the quantitative relationship between the
camera output signal and the radiance of the target
Interior orientation elements calibration To measuring the focal length and main point location
Image test
Still imaging test: to evaluate still image quality at
different distance
Sampling video test: to evaluate the sample image
quality of video at different distance
Open window video test: to evaluate the open window
image quality of video at different distance
Automatic exposure test
To evaluate the function of automatic exposure image
under different light intensity
Image compression test
To evaluate image quality difference and data rate
before and after compression
Lunar dust occlusion test
To evaluate the imaging quality under different lunar
dust condition
Color calibration
To obtain white balance correction matrix and color
correction matrix
1) Principle and method of flat field calibration
The flat field calibration method of morphology camera was the same of the descent
camera. When the dark current was subtracted from the images under different radial
brightness, R (red), G (green) and B (blue) channel image data would be obtained
respectively, and then the calibration coefficients of each channel would be obtained
by the least squares fitting method.
2) Principle and method of absolute radiation calibration
The absolute radiation calibration method of morphology camera was the same of
descent camera. But the light should be monochromatic light source, R, G, B channel
image data should be adopted in different exposure time and under different radial
brightness respectively, after the flat field calibration, the R, G, B channel absolute
calibration coefficient would be obtained.
3) Principle and method of interior orientation elements calibration
The calibration method of the interior orientation elements of morphology camera
was the same of descent camera.
4) Principle and method of video test
The video tests of morphology camera included: still imaging, sampling video and
open window video.
The video test method of morphology camera was the same of descent camera, as
shown in Fig. 16.3. The video test could be conducted under the natural atmosphere.
16 Scientific Instrument Technology of Lunar Lander
Table 16.9 Calibration and special tests of morphology camera
Tests
Purpose
Flat fielding calibration
Camera dark current detection and relative radiation
calibration
Absolute radiation calibration
To establish the quantitative relationship between the
camera output signal and the radiance of the target
Interior orientation elements calibration To measuring the focal length and main point location
Image test
Still imaging test: to evaluate still image quality at
different distance
Sampling video test: to evaluate the sample image
quality of video at different distance
Open window video test: to evaluate the open window
image quality of video at different distance
Automatic exposure test
To evaluate the function of automatic exposure image
under different light intensity
Image compression test
To evaluate image quality difference and data rate
before and after compression
Lunar dust occlusion test
To evaluate the imaging quality under different lunar
dust condition
Color calibration
To obtain white balance correction matrix and color
correction matrix
1) Principle and method of flat field calibration
The flat field calibration method of morphology camera was the same of the descent
camera. When the dark current was subtracted from the images under different radial
brightness, R (red), G (green) and B (blue) channel image data would be obtained
respectively, and then the calibration coefficients of each channel would be obtained
by the least squares fitting method.
2) Principle and method of absolute radiation calibration
The absolute radiation calibration method of morphology camera was the same of
descent camera. But the light should be monochromatic light source, R, G, B channel
image data should be adopted in different exposure time and under different radial
brightness respectively, after the flat field calibration, the R, G, B channel absolute
calibration coefficient would be obtained.
3) Principle and method of interior orientation elements calibration
The calibration method of the interior orientation elements of morphology camera
was the same of descent camera.
4) Principle and method of video test
The video tests of morphology camera included: still imaging, sampling video and
open window video.
The video test method of morphology camera was the same of descent camera, as
shown in Fig. 16.3. The video test could be conducted under the natural atmosphere.