Phase Sampling Profilometry

Structured light 3D surface imaging is a school of techniques in which structured light patterns are used for measuring the depth map of the object. Among all the designed structured light patterns, phase pattern has become most popular because of its high resolution and high accuracy. Accordingly, phase measuring profolimetry (PMP) has become the mainstream of structured light technology. In this letter, we introduce the concept of phase sampling profilometry (PSP) that calculates the phase unambiguously in the spatial-frequency domain with only one pattern image. Therefore, PSP is capable of measuring the 3D shapes of the moving objects robustly with single-shot.

Active stereo vision three-dimensional reconstruction by RGB dot pattern projection and ray intersection

Active stereo vision is important in reconstructing objects without obvious textures. However, it is still very challenging to extract and match the projected patterns from two camera views automatically and robustly. In this paper, we propose a new pattern extraction method and a new stereo vision matching method based on our novel structured light pattern. Instead of using the widely used 2D disparity to calculate the depths of the objects, we use the ray intersection to compute the 3D shapes directly. Experimental results showed that the proposed approach could reconstruct the 3D shape of the object significantly more robustly than state of the art methods that include the widely used disparity based active stereo vision method, the time of flight method and the structured light method. In addition, experimental results also showed that the proposed approach could reconstruct the 3D motions of the dynamic shapes robustly.

Slope Difference Distribution and Its Computer Vision Applications

Slope difference distribution (SDD) is computed from the one-dimensional curve and makes it possible to find derivatives that do not exist in the original curve. It is not only robust to calculate the threshold point to separate the curve logically, but also robust to calculate the center of each part of the separated curve. SDD has been used in image segmentation and it outperforms all classical and state of the art image segmentation methods. SDD is also very useful in calculating the features for pattern recognition and object detection. For the gesture recognition, SDD achieved 100% accuracy for two public datasets: the NUS dataset and the near-infrared dataset. For the object recognition, SDD achieved 100% accuracy for the Kimia 99 dataset. In this memorandum, I will demonstrate the effectiveness of SDD with some typical examples.

A New Clustering Method Based on Morphological Operations

With the booming development of data science, many clustering methods have been proposed. All clustering methods have inherent merits and deficiencies. Therefore, they are only capable of clustering some specific types of data robustly. In addition, the accuracies of the clustering methods rely heavily on the characteristics of the data. In this paper, we propose a new clustering method based on the morphological operations. The morphological dilation is used to connect the data points based on their adjacency and form different connected domains. The iteration of the morphological dilation process stops when the number of connected domains equals the number of the clusters or when the maximum number of iteration is reached. The morphological dilation is then used to label the connected domains. The Euclidean distance between each data point and the points in each labeled connected domain is calculated. For each data point, there is a labeled connected domain that contains a point that yields the smallest Euclidean distance. The data point is assigned with the same labeling number as the labeled connected domain. We evaluate and compare the proposed method with state of the art clustering methods with different types of data. Experimental results show that the proposed method is more robust and generic for clustering two-dimensional or three-dimensional data.

Is deep learning a good choice for image segmentation?

Deep learning works as a discrete non-linear mapping function and has achieved great success as a powerful classification tool. However, it has been overhyped in many fields. This comment takes image segmentation as a typical filed to prove this point of view. Firstly, deep learning is not omnipotent. It only generates a prediction map and relies on other segmentation methods to complete the segmentation task. Secondly, the performance of deep learning is inversely proportional to the number of outputs. Consequently, deep learning is not a good choice for image segmentation unless the resolution of the image is extremely small.