Line Features In Image Research Articles

Prominent expression method for line features in multiview reconstruction

In multi-view reconstruction, mesh models are one of the most important data carriers. However, existing reconstruction methods have not adequately considered the existence of real-world edge features, resulting in insufficient utilization of geometric feature information from images. This leads to issues such as surface distortion and a lack of prominent edge features in the reconstructed mesh models. To address these challenges, this paper proposes a method of line features prominent expression during the multi-view reconstruction process. This algorithm integrates image line features and the mesh model to enhance geometric features. Specifically, in this paper, the line features on the image are first extracted, and the 2D line features are sampled and fitted to synthesize 3D line features by depth map. Then, it clusters the 3D line features and establishes minimum bounding boxes. Finally, the mesh line features are determined based on graph cut methods and are prominently expressed in the mesh model. Experimental validation demonstrates that in terms of the accuracy of line feature expression, the average reprojection pass rate for line features in five datasets reaches 93.7 %. This proves that this method significantly mitigates the issue of unclear edge features on the model surface, greatly improving the visual quality of mesh models while maintaining a high accuracy.

Edge-Preserving Stereo Matching Using LiDAR Points and Image Line Features

This letter proposes a LiDAR and image line-guided stereo matching method (L2GSM), which combines sparse but high-accuracy LiDAR points and sharp object edges of images to generate accurate and fine-structure point clouds. After extracting depth discontinuity lines on the image by using LiDAR depth information, we propose a trilateral update of cost volume and depth discontinuity lines-aware semi-global matching (SGM) strategies to integrate LiDAR data and depth discontinuity lines into the dense matching algorithm. The experimental results for the indoor and aerial datasets show that our method significantly improves the results of the original SGM and outperforms two state-of-the-art LiDAR constraints’ SGM methods, especially in recovering the 3-D structure of low-textured and depth discontinuity regions. In addition, the 3-D point clouds generated by our proposed method outperform the LiDAR data and dense matching point clouds generated by Metashape and SURE aerial in terms of completeness and edge accuracy.

ORIENTATION MODELING FOR AMATEUR CAMERAS BY MATCHING IMAGE LINE FEATURES AND BUILDING VECTOR DATA

Abstract. With the popularity of geospatial applications, database updating is getting important due to the environmental changes over time. Imagery provides a lower cost and efficient way to update the database. Three dimensional objects can be measured by space intersection using conjugate image points and orientation parameters of cameras. However, precise orientation parameters of light amateur cameras are not always available due to their costliness and heaviness of precision GPS and IMU. To automatize data updating, the correspondence of object vector data and image may be built to improve the accuracy of direct georeferencing. This study contains four major parts, (1) back-projection of object vector data, (2) extraction of image feature lines, (3) object-image feature line matching, and (4) line-based orientation modeling. In order to construct the correspondence of features between an image and a building model, the building vector features were back-projected onto the image using the initial camera orientation from GPS and IMU. Image line features were extracted from the imagery. Afterwards, the matching procedure was done by assessing the similarity between the extracted image features and the back-projected ones. Then, the fourth part utilized line features in orientation modeling. The line-based orientation modeling was performed by the integration of line parametric equations into collinearity condition equations. The experiment data included images with 0.06 m resolution acquired by Canon EOS Mark 5D II camera on a Microdrones MD4-1000 UAV. Experimental results indicate that 2.1 pixel accuracy may be reached, which is equivalent to 0.12 m in the object space.

ORIENTATION MODELING FOR AMATEUR CAMERAS BY MATCHING IMAGE LINE FEATURES AND BUILDING VECTOR DATA

With the popularity of geospatial applications, database updating is getting important due to the environmental changes over time. Imagery provides a lower cost and efficient way to update the database. Three dimensional objects can be measured by space intersection using conjugate image points and orientation parameters of cameras. However, precise orientation parameters of light amateur cameras are not always available due to their costliness and heaviness of precision GPS and IMU. To automatize data updating, the correspondence of object vector data and image may be built to improve the accuracy of direct georeferencing. This study contains four major parts, (1) back-projection of object vector data, (2) extraction of image feature lines, (3) object-image feature line matching, and (4) line-based orientation modeling. In order to construct the correspondence of features between an image and a building model, the building vector features were back-projected onto the image using the initial camera orientation from GPS and IMU. Image line features were extracted from the imagery. Afterwards, the matching procedure was done by assessing the similarity between the extracted image features and the back-projected ones. Then, the fourth part utilized line features in orientation modeling. The line-based orientation modeling was performed by the integration of line parametric equations into collinearity condition equations. The experiment data included images with 0.06 m resolution acquired by Canon EOS Mark 5D II camera on a Microdrones MD4-1000 UAV. Experimental results indicate that 2.1 pixel accuracy may be reached, which is equivalent to 0.12 m in the object space.

Rigid motion and structure from several sets of parallel lines in a monocular image sequence

An image line is a very reliable feature in the feature-based structure-from-motion (SFM) problem. It has at least three advantages: (1) it is not easily affected by occlusion. (2) It can achieve subpixel accuracy. (3) The correspondence problem is easier and less ambiguous. Although some generalized SFM algorithms using image line features have been recently developed, they usually suffer from high error sensitivity and large matrix size. Besides, in order to make their estimations more robust, many line correspondences (much more than the least requirement in theory) are usually needed. These shortages are not beneficial for practical use. Because many sets of parallel lines are frequently encountered in an artificial 3D environment and can be easily identified, we try to utilize these identified parallel lines to simplify the generalized SFM problem and improve the performance of parameter estimation. A fast and reliable algorithm is proposed in our paper. Both computer-generated and real-world images are tested and several satisfactory results have been obtained. In addition, its error sensitivity and data degeneracy will be discussed.