Method and system of calibrating a multispectral camera on an aerial vehicle
A method and system of calibrating multispectral images from a camera on an aerial vehicle, the method including: capturing multispectral images of an area at a plurality of intervals with a multispectral imaging camera; simultaneously or at an arbitrary time capturing sunlight radiance data for each of the captured images; correlating the images with the sunlight radiance data; and calibrating the multispectral images based on the sunlight radiance data to normalize the multispectral images to one or more previous images of the area.
1. A method of calibrating multispectral images from a camera on an unmanned aerial vehicle, the method comprising:
capturing multispectral images of an area of land at a plurality of intervals with a multispectral imaging camera;
simultaneously capturing sunlight radiance data for each of the captured images with a solar radiance sensor mounted on an upper portion of the unmanned aerial vehicle and monitoring an area above the unmanned aerial vehicle;
correlating the images with the sunlight radiance data;
calibrating the multispectral images based on the sunlight radiance data to normalize the multispectral images to one or more previous images of the area;
monitoring an intensity level of the sunlight radiance data for detection of one or more clouds; and
changing the direction of flight of the unmanned aerial vehicle to reduce an impact of shadows from the one or more clouds.
2. The method of claim 1 , comprising:
georeferencing each of the captured images using a positioning system.
3. The method of claim 1 , comprising:
storing the multispectral images in bands, each band representing a wavelength of light.
4. The method of claim 1 , comprising:
adjusting the multispectral images using a calibration curve based on the sunlight radiance data.
5. The method of claim 4 , wherein the calibration curve is a linear curve.
6. The method of claim 4 , wherein the calibration curve is a non-linear curve.
7. The method of claim 1 , comprising:
implementing a time delay calibration value, wherein the time delay calibration comprises:
obtaining first solar radiation data at a first point;
flying the unmanned aerial vehicle into a direction of the sun and obtaining second solar radiation data at a second point; and
calibrating the multispectral imaging camera based on the first and second solar radiation data and an estimated sun position based on the first solar radiation data.
8. A system for calibrating multispectral images from a camera on an unmanned aerial vehicle, the system comprising:
the unmanned aerial vehicle configured to:
capture multispectral images of an area of land at a plurality of intervals with a multispectral imaging camera;
simultaneously capture sunlight radiance data for each of the captured images with a solar radiance sensor mounted on an upper portion of the unmanned aerial vehicle and monitoring an area above the unmanned aerial vehicle; and
a computer configured to:
correlate the images with the sunlight radiance data;
calibrate the multispectral images based on the sunlight radiance data to normalize the multispectral images to one or more previous images of the area;
monitor an intensity level of the sunlight radiance data for detection of one or more clouds; and
change the direction of flight of the unmanned aerial vehicle to reduce an impact of shadows from the one or more clouds.
9. The system of claim 8 , wherein the unmanned aerial vehicle georeferences each of the captured images using a positioning system.
10. The method of claim 8 , wherein the unmanned aerial vehicle is configured to store the multispectral images in bands, each band representing a wavelength of light.
11. The system of claim 8 , wherein the computer is configured to:
adjust the multispectral images using a calibration curve based on the sunlight radiance data.
12. The system of claim 11 , wherein the calibration curve is a linear curve.
13. The system of claim 11 , wherein the calibration curve is a non-linear curve.
14. The system of claim 8 , wherein the unmanned aerial vehicle is configured to:
detect the one or more clouds by monitoring an intensity level of the sunlight radiance data; and
implement a time delay calibration value, wherein the time delay calibration comprises:
obtaining first solar radiation data at a first point;
flying the unmanned aerial vehicle into a direction of the sun and obtaining second solar radiation data at a second point; and
calibrating the multispectral imaging camera based on the first and second solar radiation data and an estimated sun position based on the first solar radiation data.