Image stitching for construction of seabed mosaics

Решается задача сшивки фотографических изображений при построении карт морского дна на основе известных положений и ориентаций камеры автономного необитаемого подводного аппарата и расположения характерных (особых) точек на дне. Рассматриваются два алгоритма: простая сшивка, когда участок дна, видимый на каждом изображении, аппроксимируется плоскостью, и сшивка на основе трехмерной модели дна. Purpose. Seabed mosaics are built of tens of thousands of images obtained by the AUV at a small distance from the bottom. The height of the survey is limited by the power of the AUV lighting equipment and the transparency of the water and is often comparable with the differences in the heights of the bottom. This leads to strong distortions caused by parallax, which makes standard stitching methods inapplicable to the construction of photographic maps of the bottom with a complex relief. Methodology. The article proposes to consider the problem of constructing seabed mosaics as a problem of 3D reconstruction. Two approaches to stitching images are described: simple stitching and based on a 3D bottom model. With simple stitching, the relief represented by each image is approximated by a plane that is then projected onto the common plane of the seabed mosaic. When stitching based on a 3D model, the bottom section model is first constructed using the Delaunay triangulation, and then each triangle of the model is projected onto the plane of the map using a graphic accelerator GPU. To mix colors, a simple method of weighting the pixels of images is used, depending on their distance from the edges of the image. Findings. Stitching algorithms proposed in the paper were tested on images obtained by both real AUV and synthetic images. This allowed us to verify efficiency of stitching algorithms for conditions of a highly complex relief. In combination with simple color blending techniques, proposed algorithms have shown their practical efficiency. The stitching algorithm, based on the 3D model demonstrated its robustness to distortions caused by parallax. Originality/value. The main advantage of described approach is an absence of necessity to use computationally consuming, nontrivial color blending techniques while constructing seabed mosaics in the case of complex bottom relief.

Research and Design of Superscalar Pipeline Processor Based on CPLD Technology

Superscalar pipelining is to improve instruction-level parallelism and advanced technology, and is widely used in the computer's central processor and graphic accelerator. In this paper, we made use of advantage of CPLD devicesinherent flexibility, usability, predictability and so on, to achieve superscalar pipelining, designed and constructed a processor model superscalar pipeline machine based on RISC instruction set. Using EDA technology with top-down design methods, and gave the processor model hardware verification and performance test results, and had explored the use of EDA technology processor design ideas and methods.