广州市城市三维景观地图网站的建设与开发

基于GIS、三维建模、虚拟仿真等相关技术,建立了广州市城市三维景观地图数据库,开发了三维景观地图网站,并应用于第16届广州亚运会地图网站,本文对网站数据内容及模型标准（包括数据范围和内容、三维模型数据精度、三维场景效果）、三维景观地图制作流程（包括数据源获取、地物CAD建模、场景渲染及拼接）、网站功能（三维景观地图的查...     

一种基于频域相关技术的柱面全景图生成方法

在虚拟全景空间的构建中,360°柱面全景图象拼接是一项关键技术。该文通过对拍摄的实景图象做快速傅立叶变换,利用图象互功率谱的相位信息来实现全景图象的拼接,实验表明该方法大大提高了拼接速度,并且能够有效地克服图象间光照变化对拼接的影响,是一种快速实用的全景图拼接方法。     

Visual odometry and image mosaicing for NDE

Miniature robotic vehicles are receiving increasing attention for use in non-destructive testing (NDT) due to their attractiveness in terms of cost, safety and their accessibility to areas where manual inspection is not practical. Cameras can play several roles in a robotic system as a result of the information rich nature of the 2D image signal including object/shape recognition, motion estimation and ranging. This paper considers a robot configured with a single camera that monitors the surface of the structure under the robot as it moves. Visual odometry is demonstrated that can reliably track the robot's position. An image mosaicing approach is presented that calculates the robot's path using the complete image set, taking account of overlapping images that were not consecutive in the image stream. It is shown that this significantly reduced the absolute error of the positional estimate. The system was found to work well on surfaces that were not highly reflecting including steel which is common in industrial plant.     

Layered Representation of a Video Shot with Mosaicing

: This paper presents a motion segmentation method useful for representing efficiently a video shot as a static mosaic of the background plus sequences of the objects moving in the foreground. This generates an MPEG-4 compliant, layered representation useful for video coding, editing and indexing. First, a mosaic of the static background is computed by estimating the dominant motion of the scene. This is achieved by tracking features over the video sequence and using a robust technique that discards features attached to the moving objects. The moving objects get removed in the final mosaic by computing the median of the grey levels. Then, segmentation is obtained by taking the pixelwise difference between each frame of the original sequence and the mosaic of the background. To discriminate between the moving object and noise, temporal coherence is exploited by tracking the object in the binarised difference image sequence. The automatic computation of the mosaic and the segmentation procedure are illustrated with real sequences experiments. Examples of coding and content-based manipulation are also shown. Received: 31 August 2000, Received in revised form: 18 April 2001, Accepted: 20 July 2001     

一种多尺度PHOG特征和最优缝合线的运动场景图像拼接算法

针对运动物体对图像拼接易造成配准误差和合成鬼影的问题,提出一种多尺度PHOG特征和最优缝合线的运动场景图像拼接算法。首先,在多尺度空间角点检测的基础上,引入分层梯度方向直方图(PHOG)描述方法,生成多尺度PHOG特征,进行稳定配准,避免运动物体的局部影响。然后,通过构建能量函数,采用图割算法搜索几何、灰度差异最小的缝合线,去除运动鬼影。实验结果表明,该方法对存在运动物体的场景拼接具有较高的拼接精度,拼接效果良好。     

基于傅里叶变换的红外热波图像拼接*

红外热波无损检测中,红外热波空间序列图像间的变化主要是位移和小幅度旋转。针对该特点,在可能的旋转角度范围内,利用傅里叶变换的相位相关技术判定旋转的角度和平移量,实现图像的配准,然后实现图像的拼接。实验结果表明,该方法能够对重叠面积较小的图像序列实现快速拼接。     

Local object-based super-resolution mosaicing from low-resolution video

Many efficient super-resolution methods have been presented in the past for improving resolution of images degraded by global blurs. Unfortunately, in video, more complex situations can be observed where local blurs appear in each frame which are mainly caused by object motions. To address this problem, we propose in this article a local super-resolution method which allows the restoration of such local blurs. Moreover, the motion of objects in video sequences may be very complex and particularly in very low-resolution sequences it is difficult to estimate their motion exactly enough to superimpose them for super-resolution. To this end, we present a generic method: An interpolation method is proposed to improve the resolution of moving objects and we derive from this a super-resolution method for the scene background.     

Super-resolution mosaicing from MPEG compressed video

In this paper we address the problem of mosaic construction from MPEG 1/2 compressed video for the purpose of video browsing. State-of-the-art mosaicing methods work on raw video, but most video content is available in compressed form such as MPEG 1/2. Applying these methods to compressed video requires full decoding which is very costly. The resulting mosaic is in general too large to display on the screen and is thus inappropriate for the purpose of video browsing. Therefore, we directly extract very low-resolution frames from MPEG 1/2 compressed video for the mosaic construction and then apply a super-resolution (SR) method based on iterative backprojections in order to increase the mosaic resolution and its visual quality. Global motion to be used in the SR method for aligning and warping the frames is estimated from motion information contained in the compressed stream. We also use the estimated global motion in the blur estimation and in the choice of the degradation model used for the restoration in the SR algorithm. The method for the SR mosaic construction from MPEG 1/2 compressed video that we present in this paper is less costly than mosaic construction from full decoded video. Furthermore, the resulting mosaic size is more appropriate for the purpose of video browsing.