Method for measuring and modeling bidirectional reflection distribution function of inner surface of hole

Abstract

A hole inner surface bidirectional reflectance distribution function measuring and modeling method comprises the specific steps of 1, obtaining image brightness information of a hole with a known inner surface three-dimensional shape through an endoscope, 2, measuring a hole inner surface BRDF value according to the radiation irradiance of each point of the hole inner surface and the reflection radiance reflected into the lens direction, and 3, calculating the BRDF value of the hole inner surface according to the BRDF value of the hole inner surface. 3, according to the relation between the hole inner surface BRDF and the three-dimensional morphology of the hole inner surface BRDF, establishing a hole inner surface two-way reflectance distribution function inBRDF model, 4, performing experimental measurement on the inner surface BRDF value of a specific material hole, and determining the optimal parameter of the inBRDF model of the specific material by adopting a genetic algorithm; the invention discloses a hole inner surface BRDF (Bidirectional Reflection Distribution Function) measurement method based on endoscopic image brightness and normal distribution of a hole inner surface, which comprises the following steps of: improving a Phong model, establishing a hole inner surface inBRDF statistical model, and establishing a relationship between the hole inner surface BRDF and a three-dimensional shape; the method provided by the invention can effectively measure the bidirectional reflection distribution function of the inner surface of the hole, hole and cavity structure, the efficiency is high, the equipment universality is strong, the established inBRDF model can quickly and accurately obtain the BRDF value of the continuous angle of the inner surface of the hole, and the method can be applied to the quality detection of the inner surface of the hole based on machine vision.

Description

technical field [0001] The invention relates to the technical field of machining, in particular to a method for measuring and modeling a bidirectional reflection distribution function of a hole inner surface. Background technique [0002] Hole parts are the most common form of parts in machining and manufacturing. For a long time, the quality of hole parts, especially the quality of the inner surface of the hole, has been a difficult problem for enterprises. The reflection characteristic refers to the distribution law of the light energy mirror and diffuse reflection on the surface of the object after receiving light irradiation. Usually, the ratio of the incident irradiance of the point light source to the reflected radiance in the observation direction is the bidirectional reflection distribution function ( BRDF) to describe. The method of obtaining the reflection image of the surface of the object under specific lighting conditions and using the reflection characteristic...

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Problems solved by technology

Patent application CN103699810A discloses a modeling method of bidirectional reflectance distribution function in the microwave section of rough surface. According to the relationship between the rough surface scattering coefficient and the bidirectional reflectance distribution function, the bidirectional reflectance distribution function of the rough surface is obtained, which belongs to the typical BRDF indirect measurement , but only the BRDF measurement in the microwave band cannot realize the BRDF measurement at the frequency of visible light, and it is also impossible to realize the BRDF measurement and modeling of the inner surface of the hole, hole and cavity structure

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