JP2008136411A - Correction method in remote sensing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction method using a correction obtained from crop information in one field in remote sensing filming a field, and capable of correcting, based on the correction, crop information obtained from image data of filming a field different from the above field. <P>SOLUTION: This correction method comprises a process of obtaining crop information of a basic field as a base, a process of filming a field near the base field so as to include the partial area of the base field in a filming range, a process of obtaining crop information of the area as basic crop information from the crop information, a process of obtaining crop information of the near field from image data obtained by the filming, a process of obtaining crop information in a range corresponding with the area from the image data, and a process of obtaining difference between the basic crop information and the crop information so as to correct the crop information of the near field by the difference. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for efficiently correcting image data of a plurality of fields in measurement by remote sensing.

  Conventionally, as described in Patent Document 1, remote sensing that obtains crop information of a crop in the field from the image data obtained by taking a picture of the crop in the field while looking down obliquely downward from the side of the field It has been known. In the remote sensing of Patent Document 1, crop information of a part of the crop in the field is obtained by measurement with a portable measuring device, and a correction value or a correction conversion formula (hereinafter referred to as “correction value”) is obtained using this crop information. ) To create.

However, the correction value is used only for the crop information obtained from the image data of the field used to create the correction value, and is used to correct the crop information obtained from the separately captured image data of the different fields. There was a problem that could not be used. For this reason, it is necessary to obtain the correction value for each field to be photographed, and work efficiency is very poor. In order to solve this problem, the correction value obtained by the method described in Patent Document 1 can be used for correction of crop information obtained from image data obtained by photographing another field. It is desired.

JP 2000-350517 A

  In view of the above problems, the present invention uses a correction value obtained from crop information of one field in remote sensing for photographing a plurality of fields while looking down from the ground, and based on this correction value, the field is It is a technical problem to enable correction of crop information obtained from image data obtained by photographing different fields.

  In order to solve the above-mentioned problems, the present invention provides a step of obtaining crop information of a reference field as a reference in remote sensing for measuring crop information in the field, and includes a part of the reference field in the imaging range. A step of photographing a field in the vicinity of the reference field, a step of obtaining crop information of the area as reference crop information from the crop information, and crop information of the nearby field from the image data obtained by the photographing. A step of obtaining crop information in a range corresponding to the area from the image data, and a step of obtaining a difference between the reference crop information and the crop information. The correction method is characterized by correcting the difference. Furthermore, it is possible to newly use a field whose crop information is corrected by the correction method as a reference field.

  According to the invention described in the present application, a field where a crop with corrected crop information grows is set as a reference field, and a field different from the reference field is photographed by remote sensing so that a part of the reference field is included. By doing so, it becomes possible to correct another field based on the correction value obtained in one field. Therefore, it is possible to work efficiently without reducing the measurement accuracy.

  In addition, since the field for which the correction of the crop information has been completed can be newly set as the reference field, it was obtained in one field by repeating imaging of another field so that a part of the field is included. A plurality of fields can be corrected using one correction value.

  The best mode for carrying out the present invention will be described below with reference to the drawings. First, a method for photographing a farm field by remote sensing will be described. Here, the case where the crop grown in the field is paddy rice and the measurement target is the nitrogen content of the paddy rice (rice body) will be described as an example. The present invention is not limited to paddy rice, and can be used in the case of crops such as upland rice and wheat, and the measurement target is not limited to the nitrogen content of the crop, but the nitrogen content of the leaf blades It is also possible to measure the rate and the predicted protein value that the grain contains after harvesting.

  Regarding remote sensing for photographing a farm field from above obliquely with a camera installed on the ground, there is a detailed description in JP-A-2000-350517, JP-A-2001-45867, and JP-A-2001-45868, Only the outline will be described here. FIG. 2 shows an example of photographing the field 2, and the camera 3 is installed at a predetermined position toward the field 2 where the rice is grown. The field 2 is exposed to natural light. Reference numeral 4 denotes a reference plate, and the reference plate 4 may be installed at a position where the camera 3 can receive reflected light from the natural light of the reference plate 4. Further, the entire field 2 is included in the shooting range of the camera 3. The camera 3 is connected to the data processing device 20. The data processing device 20 may be any device as long as it can process image data captured by the camera 3. For example, a general laptop computer can be used. Reference numeral 21 denotes a portable measuring device, which will be described later, necessary for correcting the measurement value obtained by the camera 3. Here, the farm field 2 may be a single farm field divided by “edges” or may be a “farm field group” including a plurality of farm fields.

  FIG. 3 is a simplified block diagram showing functions of the camera 3. The camera 3 includes a CCD 5. A filter wheel 7 having a plurality of narrow band filters 6 is attached to the camera 3. By rotating the filter wheel 7, the narrow band filter 6 can be switched and photographing can be performed with each narrow band filter 6. The light transmitted through the narrow band filter 6 is received by the CCD 5 through the condenser lens 8. The filter wheel 7 is rotated by a stepping motor 10 that is driven and controlled by the control circuit 9. Further, the control circuit 9 sends image data obtained by receiving light by the CCD 5 to the data processing device 20. The narrow band filter 6 may be appropriately selected from the visible light wavelength and the near infrared wavelength corresponding to the measurement target of the crop to be measured. In FIG. 3, four narrowband filters 6 are shown. However, the narrowband filters 6 can be changed at any time according to the purpose, and RGB signals may be captured instead of the narrowband filters 6.

によって求まる。次に、カメラ３で測定した圃場２の稲体の反射光量をＺとすると、

によって、稲体の反射率Ｕが求まる。このように、反射率が既知の基準板４を用いて稲体の反射率を求めることで気象（照度）の影響を除去することができる。なお、この稲体の反射率は、稲体の窒素含有率を求めるために使用する。 In the photographing by the camera 3, the light received by the CCD 5 is reflected light by the natural light of the rice body in the field 2 and the reference plate 4. The amount of light reflected by the natural light of the rice body fluctuates due to the influence of weather (illuminance). Therefore, the amount of reflected light from the rice plant in the field 2 and the reference plate 4 is simultaneously measured, the reflectance of the rice plant is obtained by the ratio of the reflected light amount of the rice plant and the reflected light amount of the reference plate 4, and the reflectance is used. To eliminate the influence of weather (illuminance). Specifically, if the reflectance of the reference plate 4 is constant at 95% and the amount of reflected light of the reference plate 4 is X, the reference reflection amount Y as a reference is

It is obtained by. Next, let Z be the amount of light reflected from the rice field in the field 2 measured by the camera 3.

Thus, the reflectance U of rice is obtained. Thus, the influence of the weather (illuminance) can be removed by obtaining the reflectance of the rice plant using the reference plate 4 having a known reflectance. The reflectance of this rice plant is used to determine the nitrogen content of the rice plant.

  The amount of reflected light from the rice plant and the reference plate 4 is measured as follows. The narrow-band filters 6 are switched and the reflected light from the rice field and the reference plate 4 of the field 2 by natural light transmitted through the narrow-band filters 6 is received by the CCD 5 of the camera 3. The image data obtained by receiving the light is sent to the data processing device 20. In the data processing device 20, the amount of reflected light of the rice body and the reference plate 4 is obtained by calculation from the image data. By applying these reflected light amounts to Equation 1 and Equation 2, the reflectance of rice plants can be obtained. The incident light to the camera 3 is different between the reflected light from the field to the camera 3 and the reflected light from the field near the camera 3 and the reflected light from the field far from the camera 3. Therefore, it is preferable to obtain the reflectance by correcting the difference in the amount of incident light due to the different incident angles.

  The data processing device 20 stores a calibration curve prepared in advance (hereinafter referred to as “first crop relational expression”). This first crop relational expression is for obtaining the nitrogen content of the rice plant from the reflectance of the rice plant. The first crop relational expression is obtained as follows. First, an area of a certain area in the field is photographed by the camera 3, and the reflectance of rice growing in the area of the certain area is obtained by each narrow band filter 6. Next, rice leaves are collected from a plurality of rice plants growing in the area of the predetermined area, and the nitrogen content of the collected rice leaves is directly obtained by chemical analysis. Then, a first crop relational expression is created using multivariate analysis or the like with the reflectance as an explanatory variable and the nitrogen content as an objective variable. Generally, the accuracy of the first crop relational expression can be increased as the number of explanatory variables and objective variables used in multivariate analysis increases. Moreover, the first crop relational expression becomes more accurate by adding sample data and updating it every year.

  Since Formula 1, Formula 2, and the first crop relational expression are stored in the data processing device 20 in advance, the camera 3 takes a picture of the reference plate 4 and the rice plant growing on the field 2 and takes the picture. When the image data obtained in this manner is sent to the data processing device 20, the data processing device 20 uses the formula 1, the formula 2, and the first crop relational expression to determine the nitrogen content of the rice plant (hereinafter referred to as “No. 1 crop information ”). Thus, the first crop information of the rice cultivated in the field is measured. In general, the first crop information is obtained as an average value for each field, and this average value is used as the first crop information for each field.

  By the way, by using a portable leaf component measuring device (hereinafter referred to as “measuring device 21”) as described in JP-A-10-96692, the nitrogen content of rice cultivated in the field 2 (Hereinafter referred to as “second crop information”) can be easily measured. Further, the first crop information can be corrected with the second crop information. Since the measuring device 21 directly measures the rice leaves to determine the nitrogen content of the rice plant, it is not affected by the measurement orientation or planting density. For this reason, in this invention, the 2nd crop information measured with the measuring apparatus 21 is used for correction | amendment of the error difference by the influence of the measurement direction of the 1st crop information, and planting density. For example, the difference between the first crop information and the second crop information is used for correction. Moreover, you may use for a correction | amendment by the method generally known besides a difference.

  For example, the nitrogen content of rice grown in the area of a certain area Y in the field 2 photographed by the camera 3 is 4.0% (first crop information) measured by the camera 3, and measured by the measuring device 21. It is assumed that the measurement is 3.0% (second crop information). In addition, the measured value by the measuring apparatus 21 is an average value obtained by measuring a plurality of rice leaves growing in the area of the constant area Y. Since the first crop information is stored in the RAM in the data processing device 20 and the second crop information is stored in the measurement device 21, the second crop information is stored in the data processing device 20. The data is input and stored in the RAM in the data processing device 20. The input method may be either automatic or manual. The data processing device 20 calculates a difference between the first crop information and the second crop information stored in the RAM, and corrects the first crop information based on the difference. Here, since the first crop information is 4.0% and the second crop information is 3.0%, the first crop information is 1.0% higher than the second crop information. . Therefore, the difference is −1.0%. By adding this difference to the first crop information, the first crop information in the area of the constant area Y in the field 2 is corrected to 3.0%.

  By storing the difference as a correction value in the RAM in the data processing device 20, the first crop information of the entire field 2 obtained by the measurement by the camera 3 can be corrected by -1.0% of the difference. it can. Thereby, the measurement which removed the influence of a measurement direction and planting density becomes realizable with the camera 3 and the data processor 20. FIG. In determining the correction value (difference), it is important that the information source of the first crop information obtained by the camera 3 and the information source of the second crop information obtained by the measuring device 21 are common. It is. That is, it is important that the rice body photographed by the camera 3 and the rice body of the rice leaf measured by the measuring device 21 are the same. Since the measurement value of the measurement device 21 is a value obtained regardless of the measurement orientation and planting density, the first crop information corrected using the measurement value, that is, the measurement value by the camera 3 is Compared to conventional remote sensing, it is less influenced by external factors. In this embodiment, the amount of reflected light from the reference plate is measured. However, when correction is performed using the second crop information, the effect on the corrected first crop information is not required even if this measurement is not performed. Absent.

  By the way, the correction value can be used effectively and accurately for correcting the first crop information of the crop growing in the field taken by the camera 3 in order to obtain the correction value. However, when the field other than the field is photographed by the camera 3 and the first crop information of the crop growing in the field is obtained from the photographed image data, the correction value can be used effectively. Is not limited. This is because the remote sensing of the present invention uses sunlight. Sunlight changes in altitude and spectral intensity every moment, but the correction value does not correspond to this change. Therefore, it is necessary to obtain the correction value by measuring the second crop information for each image data obtained by photographing the farm field. When there are many farm fields to be photographed, work efficiency is lowered. For this reason, in the correction method of the present invention, the correction value can be used even with other image data different from the image data used to create the correction value.

  The correction method of the present invention will be described with reference to FIGS. First, the field group A including the fields A1 to A4 where the crop is grown is photographed by the method described above to obtain image data A. Then, the first crop information of each of the fields A1 to A4 is obtained from the image data A. Next, the second crop information of the crop growing in the area of a certain area in the field group A is measured by the measuring device 21, and the first crop information of the crop growing in the area is obtained from the image data A. . The area is not particularly limited as long as it is within the field group A. Then, a difference between the first crop information and the second crop information is calculated, and this difference is used as a correction value, and the first crop information of each of the fields A1 to A4 is corrected by the correction value. Here, the field group A in which the crop whose first crop information is corrected by the correction value grows is defined as a reference field.

  Next, a field group B (fields B1 to B4) different from the field group A (reference field) is photographed. At this time, the image data B is obtained by photographing so that one of the fields in the field group A is included, in other words, overlapping. Here, as shown in FIG. 3, the image data B is photographed so that the field A4 which is a part of the field group A is included in the image data B as the field B1. In addition, it is preferable to provide the said area measured with the measuring apparatus 21 in the agricultural field which overlaps and image | photographs, and it is preferable to provide in the agricultural field A4 here.

  Here, the average values of the first crop information of the crops grown in the fields (A1 to A4) of the field group A obtained by the analysis of the image data A are values as shown in Table 1, respectively. Assuming that the correction value obtained using the crop information 2 is −1.0%, the corrected first crop information of the fields A1 to A4 corrected by the correction value is as shown in Table 2. Become. Here, the corrected first crop information of the field A4 photographed in duplicate with the image data A and B is set as reference crop information.

  The average value of the first crop information of each field (B1 to B4) of the field group B before correction obtained by the analysis of the image data B is a value as shown in Table 3. As shown in FIG. 3, the field A4 and the field B1 are the same field, and the corrected first field information of the field A4 as the reference crop information is 4.4%. The first crop information can be 4.4%. Since the first crop information before correction of the field B1 is 5.6%, -1.2% which is a difference between 4.4% and 5.6% is the field group B (fields B1 to B4). Is a common correction value. Therefore, the first crop information of each of the fields B1 to B4 can be corrected as shown in Table 4 by the correction value of -1.2%.

  Further, in the field group C located in the vicinity of the field group B in the same manner as when the field group B for which the first crop information has been corrected is newly set as the reference field and the field group A is set as the reference field. A method for correcting the first crop information of the growing crop will be described. First, the field group C (fields C1 to C4) is photographed so as to include a part of the fields of the field group B, and image data C is obtained. As shown in FIG. 3, the field B4 of the field group B is photographed so as to be included in the image data C as the field C1. Then, it is assumed that the average value of the first crop information of each field (C1 to C4) of the field group C before correction obtained by the analysis of the image data C is a value as shown in Table 5. Since the field B4 and the field C1 are the same field, and the corrected first crop information of the field B4 serving as the reference crop information is 5.2%, the first crop information of the field C1 is 5. It can be 2%. Since the first crop information before correction of the field C1 is 4.3%, 0.9% which is a difference between 5.2% and 4.3% is the field group C (fields C1 to C4). This is a common correction value. Therefore, the first crop information of the fields C1 to C4 can be corrected as shown in Table 6 by the correction value 0.9%.

  As described above, the field corrected using the second crop information is used as a reference field, and a different field is captured by remote sensing so that a part of the reference field is included. The value can be used to correct different fields. Although the correction up to the field group C has been described here, the field in the field group C with the first crop information corrected is set as the reference field, and the field group near the field group C includes a part of the reference field. By photographing in this way, the photographed field group can be corrected. That is, by repeating the imaging so that a part of the field in which the first crop information is corrected is included, a plurality of fields can be corrected using one correction value obtained in one field. That is, it is not necessary to obtain the correction value using the second crop information for each image data of the photographed field, and the work efficiency can be improved.

  In addition to photographing from the ground, it is also possible to photograph the field by mounting the camera 3 on a balloon, a radio-controlled flying device (airplane, helicopter), a manned airplane, an artificial satellite, or the like. The photographing from the ground means photographing with a camera so that the field is looked down from a height of 1 m to 30 m from the ground, and it is desirable to use a telephoto lens when photographing far away. By using a telephoto lens, it is possible to capture a wide range of farmland images without moving the camera.

  The correction method of the present invention can be used even when a picture is taken as shown in FIG. FIG. 4 shows an area that is a part of the field D4 of the field group D in the imaging range when the field group D composed of the fields D1 to D4 is photographed and then the field group E composed of the fields E1 to E3 is photographed. The case where it image | photographed so that D4 'might be included is shown. In addition, the area E0 in FIG. 4 has shown the range applicable to the area D4 'at the time of imaging | photography of the agricultural field group E, and the area D4' and the area E0 are the same areas. The case where it image | photographs like this is demonstrated.

  First, a field group D is imaged as a reference field, and first crop information of each of the crops growing in the fields D1 to D4 is obtained from the image data D obtained by the imaging, and the first crop information is The correction value obtained using the crop information of 2 is used for correction. Next, the first crop information of the fields E1 to E3 of the field group E and the area E0 is obtained from the image data E obtained by photographing the field group E. Then, from the corrected first crop information of the field D4, first crop information in a range limited to the section D4 'is obtained as reference crop information. Here, if the reference crop information is 4.7% and the first crop information in the area E0 before correction is 4.5%, the reference crop information and the first crop information in the area E0 before correction are set. The difference from the crop information is 0.2%, and 0.2% is a common correction value for the field group E (fields E1 to E3). Therefore, the first crop information of the fields E1 to E3 can be corrected with the correction value of 0.2%. Naturally, the fields E1 to E3 of the field group in which the first crop information is corrected can be newly used as the reference field.

It is explanatory drawing which showed the imaging | photography state. It is a schematic block diagram of the camera used for imaging | photography of a farm field. It is the figure which showed the imaging | photography range of the farm field group. It is the figure which showed the imaging | photography range of the farm field group.

Explanation of symbols

2 Farm 3 Camera 4 Reference plate 5 CCD
6 Filter 7 Filter wheel 8 Lens 9 Control circuit 10 Stepping motor 20 Data processing device 21 Measuring device

Claims (2)

In remote sensing to measure crop information in the field,
Obtaining crop information of a reference field as a reference;
Photographing a field near the reference field so that a part of the reference field is included in the photographing range;
Obtaining the crop information of the area as reference crop information from the crop information;
Obtaining crop information of the nearby field from the image data obtained by the photographing;
Obtaining crop information in a range corresponding to the area from the image data;
Obtaining a difference between the reference crop information and the crop information,
A correction method in remote sensing, wherein crop information of the nearby field is corrected by the difference. The correction method according to claim 1, wherein a field in which crop information is corrected by the correction method is set as a reference field.

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