大豆叶片三维重建及形变技术研究

目前,对于大豆叶片形态的静态模拟研究很多,并且技术已经比较成熟,但是对于叶片的三维重建以及形变建模技术研究很少,特别是形变建模技术是叶片模拟领域中的一个难题。为此,在已建立的二维大豆叶片模型的基础上,将其重构为三维模型,并提出了叶片形变建模方法,从而得到了更具有真实感的大豆叶片模型。所提出的大豆叶片形变建模方法,可为静态虚拟植物叶片建模研究提供必要的方法,具有一定的实践价值。     

基于运动恢复结构的无规则植物叶片面积三维测量方法

接触式测量植物叶片面积的方法会对叶片造成一定程度的伤害,为此本文提出一种仅利用智能手机的非接触式多类别无规则叶片面积三维测量方法.首先,采用运动恢复结构方法获取植株的三维重建点云,在HSV颜色特征空间去除叶片三维噪点;然后,利用模糊C均值聚类算法分割单个叶片,重建叶片表面三角网格;最后,通过网格法计算叶片面积.对5种不...     

基于光学相机的植物表型测量系统与时序生长模型研究

为提高形态表型检测速率,满足形态表型测量的标准化需求,以拟南芥为例,提出一种测量植物三维形态特征的方法,并建立植物时序生长方程和可视化模型,构建了一套经济实用、面向拟南芥生长过程的形态表型测量机器视觉系统。通过光学相机采集拟南芥植株的二维图像序列,利用运动中恢复结构算法生成三维点云;设计一种彩色标板,基于彩色标板的坐标系标准化方法,提取拟南芥植株的点云并标准化坐标系。与传统人工接触式测量值相比,该系统交互测量的拟南芥叶片宽度、长度、主茎长度、叶片面积、叶片间夹角的平均相对误差分别为9. 83%、10. 10%、1. 07%、4. 09%和4. 37%。利用该系统采集哥伦比亚野生型拟南芥生命周期内的形态表型信息,拟合其数学生长模型,并使用L-studio软件,将时序生长模型可视化表达。结果表明,植物固定、传感器移动的平台结构解决了传统传感器固定、植物移动方式导致的植物抖动从而影响三维重建效果的问题,可快速、准确、可靠地提取植物表型信息。基于彩色标板的点云坐标系标准化方法在每个单位时间都能够对拟南芥植物对象进行参数提取,与传统的人工接触式测量方法相比,效率高、速度快,可满足拟南芥的形态表型分析需要。     

基于三维点云的苹果树叶片三维重建研究

叶片是果树冠层的重要组成部分,对其进行三维重建研究不仅可以对叶片形态特征进行分析,还能为冠层光照分布计算以及果树整形修剪提供理论基础。三维激光扫描仪以非接触、高效、快速获取数据的优势被大量应用于三维空间信息采集工作中。本文提出一种基于三维点云的苹果树叶片结构形态三维重建方法。首先针对叶片的形态特点选择合适的三维激光扫描仪获取苹果叶片三维点云;基于包围盒法搜索K邻域,计算点云中点与其邻域点的平均距离,并设定距离阈值作为判定中心点是否为离散点的依据,进而确定离散点并去除;利用最小二乘原理实现点云局部曲面拟合以及法向量、曲率的计算,提取叶片边界点;对于非边界点部分,根据中心点法向量与其邻域法向量的关系,对点进行不同程度的精简;最后对处理后的叶片点云完成三维重建。结果表明,构建的叶片模型能够较好的保留叶片的三维形态特征,可以为果树冠层重建和光照分布计算提供基础。     

黄瓜叶片三维重建方法研究与实现

为了真实虚拟黄瓜叶片形态和叶片纹理,实现黄瓜的动态生长三维虚拟,提出了用图像处理提取黄瓜叶片边缘特征点进行叶表面重建,借助粒子系统思想构造叶片纹理并与叶表面合成的叶片三维重建方法,用曲面投影法实现叶片的弯曲变形.结果表明,该方法较好地保持了黄瓜叶片边缘形状,真实地反映了叶片纹理的细节特征以及叶片在空间的弯曲变形.     

基于脉序骨架的小麦叶精细建模研究

为了实现小麦叶形态结构的三维可视化,基于小麦叶的脉序特征,提出了基于脉序骨架的小麦叶片三维几何建模方法。用B样条曲线表示小麦叶片和叶鞘上的叶脉曲线,用球B样条模拟叶片和叶鞘上的叶脉骨架,再连接已生成的叶脉骨架上相应的点生成叶片和叶鞘上叶脉之间的叶肉,建立了具有明显的叶脉分布和厚度的小麦叶几何模型。该方法可用于其它平行叶脉植物叶片的精细建模,具有较好的真实感。     

纹理植物叶片三维可视化系统设计与试验

植物叶片的三维可视化研究已经成为虚拟植物研究热点之一。为实现带纹理植物叶片的三维可视化,本文根据叶片自身特征信息,设计并实现一种基于图像的纹理植物叶片三维可视化系统。首先,根据双目立体视觉原理,结合一种改进的张正友标定算法和数字图像相关技术实现植物叶片的三维坐标测量算法研究;然后,设计植物叶片三维可视化软硬件测量系统,通过C++结合OpenCV编程实现本文算法,Matlab2010绘图实现叶片三维可视化;最后,本系统对网纹草叶片三维可视化测量,结果表明本系统可精确实现带纹理植物叶片的三维可视化,为虚拟植物叶片提供一种方法。     

基于移动机器人平台的玉米植株三维信息采集系统

为了快速、无损、自动获取玉米植株的三维信息,设计了一种基于移动机器人平台的玉米植株三维信息采集系统。首先,通过四轮驱动移动机器人与升降平台配合,精准控制Xtion深度相机多视角采集盆栽玉米植株的三维点云数据;然后,对获取的点云进行配准拼接与滤波,实现玉米植株的三维重建;最后,对重建后的玉米模型进行叶片的分割与参数测量。该系统的移动机器人运动误差可以控制在1 cm之内,玉米植株叶片参数测量误差在1%～5%之间,证明了该系统进行玉米植株三维信息采集的可行性。     

基于多视角图像的植物叶片建模与曲面面积测量

针对现有测量植物叶片面积方法会对叶片造成一定程度的损伤,提出一种直接对自然生长状态下的叶片进行测量的方法.首先,对数码相机进行校正获取相机参数,从多角度拍摄自然生长状态下的叶片;然后,利用PhotoModeler软件对图像进行处理,获得叶片三维点云模型;再利用Matlab编程实现叶片的三维曲面建模并计算曲面面积.将该测量结果与采用扫描仪结合Photoshop测量结果进行了对比,实验结果表明,提出的方法对自然状态下的叶片测量效果良好,精度达99％.     

基于AABB-OBB盒的玉米叶片碰撞检测

在数字植物虚拟仿真场景中,植物三维模型之间容易出现交叉穿透现象,有必要进行快速有效的碰撞检测。选择以玉米叶片为研究对象,针对叶片形态提出了一种基于AABB-OBB混合包围盒的碰撞检测方法。首先通过AABB盒相交测试剔除部分未相交对象;然后根据叶片形态特点,对可能相交对象构造OBB盒二叉树。依据玉米叶片交叉常态,改进了分离轴测试顺序,提出了基于优先权值的节点搜索方式,并优化了特殊情况的图元测试过程。实验结果表明,该方法能够准确快速地检测到玉米叶片的交叉状况。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。