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Aiming at the problem that the detection of small planes with unobvious texture is easy to be missed in augmented reality scene, a 3D scene information enhancement method to grab the planes for augmented reality scene is proposed based on a series of images of a real scene taken by a monocular camera. Firstly, we extract the feature points from the images. Secondly, we match the feature points from different images, and build the three-dimensional sparse point cloud data of the scene based on the feature points and the camera internal parameters. Thirdly, we estimate the position and size of the planes based on the sparse point cloud. The planes can be used to provide extra structural information for augmented reality. In this paper, an optimized feature points extraction and matching algorithm based on Scale Invariant Feature Transform (SIFT) is proposed, and a fast spatial planes recognition method based on a RANdom SAmple Consensus (RANSAC) is established. Experiments show that the method can achieve higher accuracy compared to the Oriented Fast and Rotated Brief (ORB), Binary Robust Invariant Scalable Keypoints (BRISK) and Super Point. The proposed method can effectively solve the problem of missing detection of faces in ARCore, and improve the integration effect between virtual objects and real scenes.

Ni47Ti44Nb9 shape memory alloys (SMA) were applied to bridge pier column to resist earthquake loads by the force of recovery stress over the past decades. However, the application of hot-drawn SMA on pier column reinforcement is hardly researched despite the advantages of cost savings and simplifying service process compared to annealed SMA. Aiming at exploring the usability of hot-drawn SMA on the reinforcement, this paper focused on certain behaviors about pre-strain, thermal activation and partial recovery of recoverable strain that influence the capacity of constraint SMA to gain recovery stress, and then researched recovery stress stability and tensile properties of constraint SMA under cyclic loads both at room temperature and low temperature. Test pieces adopted in this study were 2 mm diameter hot-drawn NiTiNb SMA wires. All setups involved in the tests were self-developed. The states of recovery stress and its stability were mainly evaluated by three tests: uniaxial tensile test, thermal activation test and cyclic loading test. The results marked that hot-drawn SMA could obtain sufficient recovery stress when deformed at room temperature. Moreover, the stability of recovery stress under cyclic loading and low temperature could satisfy the demands of pier column reinforcement for practical use.

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