《立体上直线的投影》PPT课件

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1、Projectionoflines直线的投影Characteristicsoflineprojection直线的投影特性Exercises练习题ProjectionofLinesforaSolid立体上直线的投影请点击相应标题显示其内容Theresultofprojectionisalineconnectingtheprojectedpointsofthetwoendpointsoftheline.直线的投影由直线上两端点A、B同面投影的连线来确定。Projectionoflines直线的投影请点击鼠标左键显示后面内容b´b"ba´a"ab´a"b"a´

2、VHWabThepartitionofpointonalinemustbeequaltoontheprojectedline.点分线段长度之比等于其投影分线段投影长度之比。Characteristicsoflineprojection直线的投影特性1.Linearity直线性：Theprojectionofalineproducesaline.直线的投影仍然是直线(特殊情况积聚为点)。2.Parallelism平行性：Theparallelismoflinesbeforeandafterprojectiondoesnotchange.平行直线的各同面投影

3、仍然平行。3.Subordinative从属性：Theprojectionofapointonalinemustbeontheprojectedline.若点在线上,则其投影应在线的投影上。a´aa´aa"请点击鼠标左键显示后面内容A4.Proportionality定比性：VHx0YwW-perpendicularline侧垂线Z●efefe(f)XoYHYWαhorizontalβistheobliqueanglesofthecorrespondinglineformedwiththefrontalplane.γprofile与H面的夹角:α

4、；与V面的夹角:β；与W面的夹角:γ。（均为0或90）H-plane,H-perpendicular(铅垂线)IfitisverticaltotheV-plane,itiscalledaV-perpendicularline.(正垂线)W-plane,W-perpendicular(侧垂线)与某投影面垂直的直线称为该面的垂直线．Itsprojectiononitsverticalplaneconvergestoapoint.投影面垂直线在所垂直的投影面上的投影积聚为一点。Itsprojectionsontheothertwoplanesareboth

5、parallelwithanaxisofprojection,andshowsitstruelength.在另外两个投影面上的投影均平行相应的投影轴，且反映实长。Definition定义Obliquity倾角Characteristics投影特性1.Theverticallineofaprojectionplane投影面垂直线请点击鼠标左键显示后面内容H-perpendicularline铅垂线YW●aba(b)abXZoYHABABV-perpendicularline正垂线●c(d)cddcXZoYHYWCDCDEFEF2.Paral

6、lellineofaprojectionplane投影面平行线βαObliquity倾角αhorizontalβistheobliqueanglesofthecorrespondinglineformedwiththefrontalplane.γprofile与H面的夹角:α;与V面的夹角:β;与W面的夹角:γ。(总有一个为0)Definition定义Characteristics投影特性请点击鼠标左键显示后面内容H-plane,horizontal(水平线)IfitisparallelwiththeV-plane,itiscalledafrontal

7、line.(正平线)W-plane,profile(侧平线)与某投影面平行的直线称为该面的平行线．Showsitstruelengthandtheinclinationanglesformedwiththeaxesofprojectionshowtheobliqueformedwiththeothertwoplanesofprojection.在所平行的面上的投影反映实长,且反映其对另外两投影面的倾角。Itsprojectionsontheothertwoprojectionplanesareshorterthanitstruelength,andare

8、allverticaltotheaxisofprojection.在另外两个投影