Natural land cover information is important for analysing and understanding of the current terrestrial situation, especially in the study area that is facing the environmental deteriorating increasingly. The study combined the remote sensing Aster data and ground truth to improve 2001 land cover map of Guadalteba area in Spain, and increased the accuracy from 47% to 70%. The general land cover map produced about the Guadalteba study area outlines the distribution of the vegetation type and the current natural land cover in the area. Based on this improved general land cover map, the natural cover map gave an indication of the present location of nature and agriculture areas. The shrub land degradation map identified location of various shrub/matorral areas and different levels of degradation. The further analysis and discussion were done. The output maps indicated that much of the natural cover mostly dominated by formations of shrubs has been changed to agriculture and other land uses. It is observed that shrubland covers a small percentage, approximately 9% of the study area, due to land degradation in most parts caused by human interfere. Keywords Accuracy assessment - Aster - Land cover map - Matorral degradation map - Remote Sensing CLC number S757.3 Document code A Foundation item: This paper was partly sponsored by NFP (Netherlands Feliowship Program) and National Strategic Project “Environmentally Sound Forest Management Techniques and Models in Natural Forest in Northeast China” (2001BA510B0702) respectively.Biography: XING Yan-qiu (1970-), female, Lecturer, in College of Engi neering and technology Northeast Forestry University. Harbin 150040. P. R. ChinaResponsible editor: Song Funan
激光惯导融合的同步地图定位与建图(simultaneous localization and mapping,SLAM)算法可以实现林下三维点云地图构建。鉴于现有激光惯导融合SLAM算法建图的单木定位精度存在较大误差,导致建图效果难以满足林业应用要求,提出了一种局部直线拟合滤除地面点的林下SLAM算法,利用局部的直线拟合来判断地面点并滤除,提高树木特征比重,在激光惯导融合SLAM的前端匹配部分对点云数据进行建图,减小由地面点造成的树木匹配误差。在真实样地中对改进前后两种算法进行实验对比和综合量化评价。实验证明,算法改进后建图所得单木位置的平均绝对误差和均方根误差分别减少了61%和50%,说明该算法可以在林下得到更佳建图效果,可为森林资源调查提供技术支撑。
