Glue point three-dimensional reconstruction method based on uncalibrated photometric stereoscopic vision

Abstract

The invention discloses a glue point three-dimensional reconstruction method based on uncalibrated photometric stereoscopic vision. Aiming at the three-dimensional reconstruction problem of the glue point, an uncalibrated photometric stereoscopic vision solving method is provided, and a general bas-relief (GBR) parameter is solved by combining a diffuse reflection-based method and a mirror reflection-based method. The glue point three-dimensional reconstruction method comprises the following steps: carrying out picture shooting on a glue point under multiple light sources, carrying out diffuse reflection image and mirror reflection image separation on an image of the glue point, finding a Lambert reflection maximum value of the diffuse reflection image, considering half-vector symmetry in mirror reflection by using a bidirectional reflection distribution function (BRDF), finally solving a parameter value of GBR by combining the two images, and recovering a surface normal and reconstructing a three-dimensional surface through integration. According to the method, the three-dimensional reconstruction problem of the glue points is solved by adopting an integral method, so that the reconstruction result has higher accuracy. The method is suitable for a precision assembly system which has high requirements on the gluing process and strict precision requirements on the assembly performance.

Description

technical field [0001] The invention belongs to the field of three-dimensional measurement, in particular to a method for three-dimensional reconstruction of glue dots based on uncalibrated photometric stereo vision. Background technique [0002] Glue dispensing technology is a very important technology in the advanced electronics manufacturing industry, and it is widely used in the field of micro-assembly technology and integrated circuit equipment. In the dispensing process, the amount of glue dispensed and the three-dimensional shape of the glue point have an important impact on the assembly performance of the parts to be bonded. Accurate measurement of glue points is of great significance to micro-assembly technology. Existing methods for measuring the amount of glue dispensed can be divided into weighing methods and two-dimensional visual online measurement methods. For the weighing method, if the weight is directly weighed, it will be submerged because the mass of th...

AI Technical Summary

Problems solved by technology

For the weighing method, if the weight is directly weighed, it will be submerged because the mass of the glue dot is much smaller than the mass of the substrate. In fact, it can only be measured indirectly by spotting the colloid on a microslide, which is very inefficient and it is not easy to see the specific shape of the glue dot.

The two-dimensional visual measurement method is to evaluate the consistency of the glue distribution through the online measurement of the glue point area. Although its efficiency is high, this method is based on the assumption that the glue point height is consistent or the glue point is not deformed.

However, in the actual application process, the calibration of the light source is more complicated and has certain restrictions on the environment, so the uncalibrated photometric stereo technology appears, that is, to reconstruct the surface of the object in the case of an unknown light source.

There are many existing methods to solve uncalibrated photometric stereo technology, but they all assume that the object is a Lambertian body, or directly remove the image highlights for research.

Not suitable for 3D reconstruction of glue dots

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