Vegetation growth condition analysis method, recording medium on which program is recorded, and vegetation growth condition analyzer

A non-transitory computer readable recording medium recording thereon a computer program that when executed by a computer causes the computer to function as:

• an acquiring means acquiring a plurality of radar images of a ground surface of a same target area taken at multiple times of a year by a radar device mounted on a flying body;
• a storing means storing the plurality of radar images acquired by the acquiring means in a map database;
• an aligning means aligning, while using as a criterion image a radar image of the plurality of radar images stored in the map database, taken at a predetermined time in the multiple times of a year, other radar images than the criterion image of the plurality of radar images, taken at other times than the predetermined time in the multiple times of a year, with the criterion image, respectively;
• an extracting means extracting backscatter coefficients in specified areas of the plurality of radar images;
• a calibrating means calibrating backscatter coefficients of other radar images than the criterion image of the plurality of radar images stored in the map database based on a backscatter coefficient of a specified area in the criterion image of the plurality of radar images;
• and
• a calculating means calculating growth values of vegetation shown in other radar images than the criterion image of the plurality of radar images, whose backscatter coefficients have been calibrated by the calibrating means, from the backscatter coefficients thereof calibrated by the calibrating means, based on a correlation between backscatter coefficients of radar images and growth values of vegetation shown in the radar images,
• wherein the calibrating means further:
• calculates, based on a backscatter coefficient of a specified area in the criterion image of the plurality of radar images stored in the map database and backscatter coefficients of specified areas of other radar images than the criterion image of the plurality of radar images, the specified areas of other radar images of the plurality of radar images each corresponding to the specified area in the criterion image, calibration lines for calibrating backscatter coefficients of other radar images than the criterion image of the plurality of radar images, and
• calibrates, based on the calculated calibration lines, backscatter coefficients of other radar images than the criterion image of the plurality of radar images.

A vegetation growth condition analyzer comprising:

• an acquisition hardware unit configured to acquire a plurality of radar images of a ground surface of a same target area taken at multiple times of a year by a radar device mounted on a flying body;
• a storage hardware unit configured to store the plurality of radar images acquired by the acquisition hardware unit in a map database;
• and
• at least one hardware unit implementing
• an alignment hardware unit configured to align, while using as a criterion image a radar image of the plurality of radar images stored in the map database, taken at a predetermined time in the multiple times of a year, other radar images than the criterion image of the plurality of radar images, taken at other times than the predetermined time in the multiple times of a year, with the criterion image, respectively,
• an extraction hardware unit configured to extract backscatter coefficients of specified areas in the plurality of radar images,
• a calibration hardware unit configured to calibrate backscatter coefficients of other radar images than the criterion image of the plurality of radar images stored in the map database based on a backscatter coefficient of a specified area in the criterion image of the plurality of radar images, and
• a calculation hardware unit configured to calculate growth values of vegetation shown in other radar images than the criterion image of the plurality of radar images, whose backscatter coefficients have been calibrated by the calibration hardware unit, from the backscatter coefficients thereof calibrated by the calibration hardware unit, based on a correlation between backscatter coefficients of radar images and growth values of vegetation shown in the radar images,
• wherein the calibration hardware unit is further configured to:
• calculate, based on a backscatter coefficient of a specified area in the criterion image of the plurality of radar images stored in the map database and backscatter coefficients of specified areas of other radar images than the criterion image of the plurality of radar images, the specified areas of other radar images of the plurality of radar images each corresponding to the specified area in the criterion image, calibration lines for calibrating backscatter coefficients of other radar images than the criterion image of the plurality of radar images, and
• calibrate, based on the calculated calibration lines, backscatter coefficients of other radar images than the criterion image of the plurality of radar images.