US-12618789-B2 - Infrared thermal image analysis device, infrared thermal image analysis method, and program

US12618789B2US 12618789 B2US12618789 B2US 12618789B2US-12618789-B2

Abstract

Provided are an infrared image analysis device, an infrared image analysis method, and a program capable of correctly reducing a temperature gradient. An infrared thermal image analysis device ( 10 ) includes a processor. The processor acquires a first infrared thermal image of a structure surface, which is obtained by capturing a structure ( 36 ) to be inspected, acquires region information ( 105 ) that distinguishes a region of the structure surface corresponding to the first infrared thermal image for at least one region, estimates a temperature gradient in the at least one region based on the region information ( 105 ) and a second infrared thermal image, and reduces an influence of the temperature gradient from the first infrared thermal image.

Inventors

Kimito Katsuyama

Assignees

FUJIFILM CORPORATION

Dates

Publication Date: 20260505
Application Date: 20230428
Priority Date: 20201030

Claims (20)

1 . An infrared thermal image analysis device comprising a processor configured to: acquire a first infrared thermal image of a structure surface, which is obtained by capturing a structure to be inspected; consider regions with different inclinations and/or discontinuities as different regions, or consider regions differing in at least one of color, roughness, unevenness, or presence/absence of solar radiation as different regions, on the structure surface where the first infrared thermal image has been captured; acquire region information that distinguishes each of the regions, for at least one region; acquire a second infrared thermal image of the structure surface, the second infrared thermal image captured so as to include the at least one region within an imaging range; estimate a temperature gradient in the at least one region based on the region information for the at least one region and the second infrared thermal image; and reduce an influence of the temperature gradient from the first infrared thermal image.
2 . The infrared thermal image analysis device according to claim 1 , wherein the processor acquires the region information based on information related to the structure including a visible image obtained by capturing the structure.
3 . The infrared thermal image analysis device according to claim 1 , wherein the processor acquires the region information based on information related to the structure including at least one of the first infrared thermal image or the second infrared thermal image obtained by capturing the structure.
4 . The infrared thermal image analysis device according to claim 1 , wherein the processor acquires the region information based on information related to the structure including data obtained by measuring a distance to the structure.
5 . The infrared thermal image analysis device according to claim 1 , wherein the processor acquires the region information based on information related to the structure including drawing data of the structure.
6 . The infrared thermal image analysis device according to claim 1 , wherein the processor preferentially applies the second infrared thermal image in the region to the second infrared thermal image in another region to estimate the temperature gradient in the region.
7 . The infrared thermal image analysis device according to claim 6 , wherein the processor performs, in the preferential application, smoothing processing on the second infrared thermal image with different weights for the region and the other region.
8 . The infrared thermal image analysis device according to claim 6 , wherein the processor performs, in the preferential application, smoothing processing on the second infrared thermal image with extension along a boundary of the region in a range not including the other region.
9 . The infrared thermal image analysis device according to claim 1 , wherein the processor preferentially applies the second infrared thermal image in a peripheral region of the region to estimate the temperature gradient in the region.
10 . The infrared thermal image analysis device according to claim 9 , wherein the peripheral region is in a case where a smallest distance among distances from pixels in the region to each pixel on a boundary of the region is defined as a distance from each of the pixels to the boundary and a distance at a pixel having a largest distance to the boundary is defined as a distance from a center to the boundary, a region including at least a pixel whose distance to the boundary is ½ or less of the distance from the center to the boundary.
11 . The infrared thermal image analysis device according to claim 1 , wherein the processor estimates the temperature gradient in the region by thermal simulation.
12 . The infrared thermal image analysis device according to claim 1 , wherein the processor subtracts the temperature gradient from the first infrared thermal image or divides the first infrared thermal image by the temperature gradient in a case where the influence of the temperature gradient is reduced.
13 . The infrared thermal image analysis device according to claim 1 , wherein at least one of the first infrared thermal image, the second infrared thermal image, or information related to the structure on which the region information is based is acquired at a different timing.
14 . The infrared thermal image analysis device according to claim 1 , wherein at least one of the first infrared thermal image, the second infrared thermal image, or information related to the structure on which the region information is based is an image or information obtained by integrating a plurality of images or pieces of information.
15 . The infrared thermal image analysis device according to claim 1 , wherein the processor acquires the first infrared thermal image and the second infrared thermal image at a timing of solar radiation.
16 . The infrared thermal image analysis device according to claim 1 , wherein the structure surface includes at least one of a plurality of surfaces having different inclinations or discontinuous surfaces.
17 . The infrared thermal image analysis device according to claim 1 , wherein the processor displays a temperature gradient reduction image in which the influence of the temperature gradient is reduced from the first infrared thermal image on a display device.
18 . The infrared thermal image analysis device according to claim 17 , wherein the processor displays the temperature gradient reduction image subjected to image processing on the display device.
19 . The infrared thermal image analysis device according to claim 1 , wherein the first infrared thermal image and the second infrared thermal image are the same infrared thermal image.
20 . An infrared thermal image analysis method comprising: acquiring a first infrared thermal image of a structure surface, which is obtained by capturing a structure to be inspected; considering regions with different inclinations and/or discontinuities as different regions, or consider regions differing in at least one of color, roughness, unevenness, or presence/absence of solar radiation as different regions, on the structure surface where the first infrared thermal image has been captured; acquiring region information that distinguishes each of the regions, for at least one region; acquiring a second infrared thermal image of the structure surface, the second infrared thermal image captured so as to include the at least one region within an imaging range; estimating a temperature gradient in the at least one region based on the region information for the at least one region and the second infrared thermal image; and reducing an influence of the temperature gradient from the first infrared thermal image.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a Continuation of PCT International Application No. PCT/JP2021/036558 filed on Oct. 4, 2021 claiming priorities under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2020-182464 filed on Oct. 30, 2020 and Japanese Patent Application No. 2021-004181 filed on Jan. 14, 2021. Each of the above applications is hereby expressly incorporated by reference, in its entirety, into the present application. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared thermal image analysis device, an infrared thermal image analysis method, and a program. 2. Description of the Related Art There is known a technique of discriminating, by using an infrared thermal image acquired in a case where a structure such as concrete is imaged with an infrared camera, between a damaged part, such as a floating or a crack, included in the structure and a sound part. In a case where the structure has the damaged part, a temperature difference occurs between a surface temperature of the damaged part and a surface temperature of the sound part. Therefore, in a case where a portion having a temperature different from that of the surroundings is locally present in the infrared thermal image, the damaged part is discriminated to be present inside the portion. On the other hand, an amount of heat received or an amount of heat dissipated on a structure surface is partially different depending on a structure shape, an environment around the structure, or the like, and thus a temperature gradient may be generated on the structure surface. In a case where such a temperature gradient is present on the structure surface, it becomes difficult to discriminate between the sound part and the damaged part. The partial difference in the amount of heat received or the amount of heat dissipated on the structure surface may also occur due to partial differences in color or roughness, unevenness, and thermal conductivity or emissivity of the structure surface, in addition to the structure shape or the environment around the structure. To solve this problem, JP5140892B discloses that an average temperature distribution image obtained by moving and averaging an infrared thermal image with a predetermined number of pixels is created, a temperature difference between the same pixel of the infrared thermal image and the average temperature distribution image is calculated to create a temperature difference image, and the temperature difference image is displayed. SUMMARY OF THE INVENTION By the way, in a case where a structure has a plurality of surfaces having different inclinations, an average temperature and an orientation and inclination of a temperature gradient on each surface are different due to the influence of solar radiation or the like on the surface of the structure. In a case where the infrared thermal image is smoothed and the difference is taken without distinguishing between the surfaces having different average temperatures and temperature gradients in this manner, a boundary between the different surfaces is erroneously detected as the damaged part. Further, another surface is included in a pixel range used for the smoothing, and thus there is a problem that the temperature gradient cannot be reduced correctly. The present invention has been made in view of such circumstances, and an object of the present invention is to provide an infrared thermal image analysis device, an infrared thermal image analysis method, and a program capable of correctly reducing a temperature gradient. An infrared thermal image analysis device according to a first aspect of the present invention is an infrared thermal image analysis device comprising a processor. The processor acquires a first infrared thermal image of a structure surface, which is obtained by capturing a structure to be inspected, acquires region information that distinguishes a region of the structure surface corresponding to the first infrared thermal image for at least one region, estimates a temperature gradient in the at least one region based on the region information and a second infrared thermal image, and reduces an influence of the temperature gradient from the first infrared thermal image. In the infrared thermal image analysis device according to a second aspect, the processor acquires the region information based on information related to the structure including a visible image obtained by capturing the structure. In the infrared thermal image analysis device according to a third aspect, the processor acquires the region information based on information related to the structure including at least one of the first infrared thermal image or the second infrared thermal image obtained by capturing the structure. In the infrared thermal image analysis device according to a fourth aspect, the processor acquires the region information based on information related to the structure inc