Shape from focus using gradient of focus measure curve

Fu, Boya; He, Renzhi; Yuan, Ye; Jia, Wenchao; Yang, Sui; Liu, Fei

doi:10.1016/j.optlaseng.2022.107320

Cited by 14 publications

(4 citation statements)

References 31 publications

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“…The focus measure (FM) function is used to extract depth information from the multi-focused image sequence. The 3D morphology of the tested sample surface is reconstructed according to the height information [ 35 , 36 ]. The schematic of the 3D reconstruction based on the SFF algorithm using the ETL is shown in Figure 7 .…”

Section: Principle Of the Colorful 3d Reconstructionmentioning

confidence: 99%

Colorful 3D Reconstruction and an Extended Depth of Field for a Monocular Biological Microscope Using an Electrically Tunable Lens

Cheng,

Liu,

et al. 2024

Biomimetics

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This paper presents a monocular biological microscope with colorful 3D reconstruction and an extended depth of field using an electrically tunable lens. It is based on a 4f optical system with an electrically tunable lens at the confocal plane. Rapid and extensive depth scanning while maintaining consistent magnification without mechanical movement is achieved. We propose an improved Laplacian operator that considers pixels in diagonal directions to provide enhanced fusion effects and obtain more details of the object. Accurate 3D reconstruction is achieved using the shape-from-focus method by tuning the focal power of the electrically tunable lens. We validate the proposed method by performing experiments on biological samples. The 3D reconstructed images obtained from the biological samples match the actual shrimp larvae and bee antenna samples. Two standard gauge blocks are used to evaluate the 3D reconstruction performance of the proposed method. The experimental results show that the extended depth of fields are 120 µm, 240 µm, and 1440 µm for shrimp larvae, bee tentacle samples, and gauge blocks, respectively. The maximum absolute errors are −39.9 μm and −30.6 μm for the first and second gauge blocks, which indicates 3D reconstruction deviations are 0.78% and 1.52%, respectively. Since the procedure does not require any custom hardware, it can be used to transform a biological microscope into one that effectively extends the depth of field and achieves highly accurate 3D reconstruction results, as long as the requirements are met. Such a microscope presents a broad range of applications, such as biological detection and microbiological diagnosis, where colorful 3D reconstruction and an extended depth of field are critical.

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Section: Principle Of the Colorful 3d Reconstructionmentioning

confidence: 99%

Colorful 3D Reconstruction and an Extended Depth of Field for a Monocular Biological Microscope Using an Electrically Tunable Lens

Cheng,

Liu,

et al. 2024

Biomimetics

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“…The shape from focus algorithm is used to extract the three-dimensional depth point cloud data of the fuel nozzle. Different sharpness evaluation operators and window sizes of focus evaluation will directly affect the quality of focus evaluation, so it is very important to find the best focus evaluation operator and window size [ 20 ]. A small window size can preserve depth discontinuities but increase the sensitivity to noise.…”

Section: 3d Point Cloud Extraction Principle Of the Fuel Nozzlementioning

confidence: 99%

Fractal Analysis of Fuel Nozzle Surface Morphology Based on the 3D-Sandbox Method

Hou

Chen

2023

Micromachines

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The dual oil circuit centrifugal fuel nozzle is made of martensitic stainless steel, which has complex morphological characteristics. The surface roughness characteristics of the fuel nozzle directly affect the degree of fuel atomization and the spray cone angle. The surface characterization of the fuel nozzle is investigated by the fractal analysis method. A sequence of images of an unheated treatment fuel nozzle and a heated treatment fuel nozzle are captured by the super-depth digital camera. The 3-D point cloud of the fuel nozzle is acquired by the shape from focus technique, and its three-dimensional (3-D) fractal dimensions are calculated and analyzed by the 3-D sandbox counting method. The proposed method can characterize the surface morphology well, including the standard metal processing surface and the fuel nozzle surface, and the experiments show that the 3-D surface fractal dimension is positively correlated with the surface roughness parameter. The 3-D surface fractal dimensions of the unheated treatment fuel nozzle were 2.6281, 2.8697, and 2.7620, compared with the heated treatment fuel nozzles dimensions of 2.3021, 2.5322, and 2.3327. Thus, the 3-D surface fractal dimension value of the unheated treatment is larger than that of the heated treatment and is sensitive to surface defects. This study indicates that the 3-D sandbox counting fractal dimension method is an effective method to evaluate the fuel nozzle surface and other metal processing surfaces.

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“…The stacks contained between 25 and 51 images. A study of operators in the field of focus evaluation was also carried out by Fu [18]. The authors simulated surface shapes in the form of a plane surface, a cone, and a sine wave.…”

Section: Introductionmentioning

confidence: 99%

Focus Estimation Methods for Use in Industrial SFF Imaging Systems

Sioma,

Lenty

2024

Applied Sciences

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A Shape-From-Focus (SFF) is a three-dimensional imaging method based on focus information. It is not yet widely used for in-line industrial inspection or measurement tasks. The main reasons are the time it takes to capture a 3D image of the inspected product and the presence of interference affecting image quality. This paper compares operators for estimating focus in source images in the scope of their use in constructing an industrial 3D scanner. Interferences were introduced by using additional illuminators and changing the acquisition parameters. The use of industrial-grade cameras, industrial-grade illuminators, and electrically controlled optics are discussed. A novel approach in the research is using an electrically tunable lens to move the position of the image plane during 3D image acquisition. The research was conducted on various surfaces found on typical industrial products. The research showed which focus estimation operators can be applied to SFF imaging within the range of interference considered. It was also confirmed that using the centre of gravity method for scene reconstruction allows for an increase in resolution compared to the maximum method.

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Shape from focus using gradient of focus measure curve

Cited by 14 publications

References 31 publications

Colorful 3D Reconstruction and an Extended Depth of Field for a Monocular Biological Microscope Using an Electrically Tunable Lens

Colorful 3D Reconstruction and an Extended Depth of Field for a Monocular Biological Microscope Using an Electrically Tunable Lens

Fractal Analysis of Fuel Nozzle Surface Morphology Based on the 3D-Sandbox Method

Focus Estimation Methods for Use in Industrial SFF Imaging Systems

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