《立体上直线的投影》PPT课件.ppt

Projection of lines 直线的投影 Characteristics of line projection 直线的投影特性 Exercises 练习题,Projection of Lines for a Solid 立体上直线的投影,请点击相应标题显示其内容,The result of projection is a line connecting the projected points of the two end points of the line. 直线的投影由直线上两端点A、B同面投影的连线来确定。,Projection of lines 直线的投影,请点击鼠标左键显示后面内容,b,a“,b“,a,a,b,The partition of point on a line must be equal to on the projected line. 点分线段长度之比等于其投影分线段投影长度之比。,Characteristics of line projection 直线的投影特性,1. Linearity 直线性：,The projection of a line produces a line. 直线的投影仍然是直线(特殊情况积聚为点)。,2. Parallelism 平行性：,The parallelism of lines before and after projection does not change. 平行直线的各同面投影仍然平行。,3. Subordinative 从属性：,The projection of a point on a line must be on the projected line. 若点在线上,则其投影应在线的投影上。,a,a,a,a,a“,请点击鼠标左键显示后面内容,A,4. Proportionality 定比性：,x 0 Yw, horizontal is the oblique angles of the corresponding line formed with the frontal plane. profile 与H面的夹角:；与V 面的夹角:；与W面的夹角:。（均为0 或90 ）,H-plane, H-perpendicular (铅垂线) If it is vertical to the V-plane, it is called a V-perpendicular line. (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,Its projection on its vertical plane converges to a point. 投影面垂直线在所垂直的投影面上的投影积聚为一点。 Its projections on the other two planes are both parallel with an axis of projection, and shows its true length. 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. The vertical line of a projection plane 投影面垂直线,请 点 击 鼠 标 左 键 显 示 后 面 内 容,2.Parallel line of a projection plane 投影面平行线,Obliquity 倾 角, horizontal is the oblique angles of the corresponding line formed with the frontal plane. profile 与H面的夹角:;与V 面的夹角:;与W面的夹角:。 (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) If it is parallel with the V-plane, it is called a frontal 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,Shows its true length and the inclination angles formed with the axes of projection show the oblique formed with the other two planes of projection.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。 Its projections on the other two projection planes are shorter than its true length, and are all vertical to the axis of projection. 在另外两个投影面上的投影长度比实长短,且垂直于相应的投影轴。,3. A line in general position 一般位置直线,Definition 定 义,Obliquity 倾 角,Characteristics 投影特性,请点击鼠标左键显示后面内容,The line being projected is oblique with the three planes of projection. 与三个投影面都倾斜的直线称为一般位置直线。, horizontal is the oblique angles of the corresponding line formed with the frontal plane. profile 与H面的夹角:;与V 面的夹角:;与W面的夹角:。 The angle always 0or 0或 90 ),Three projections on the projection planes are shorter than its true length, and all oblique angles are not true. 三投影均小于实长，其倾角均不反映真实大小。,1. Given positions of line AB & CD, label its projection in view and fill the vacancy. 已知立体上直线AB、CD 的空间位置, 在投影图中标注其投影位置,并填空。,请点击题目显示其内容,Exercises 练习题,2. Given two projections of line AB & CD, draw the third projection and fill the vacancy. 已知直线AB、AC 的二投影,求二直线 的第三投影,并填空。,本 小 节 结 束,谢谢您的认真学习！,退出,前一页,1.Given positions of line AB & CD, label its projection in view and fill in the blank. 已知立体上直线AB、CD的空间位置,在投影图中标注其投影位置,并填空。,请 点 击 解 答 显 示 其 内 容,H-perpendicular 铅垂线,a line in general position 一般位置直线,a,a,a“,b,b,b“,c,d,c,(d),c“,d“,请 点 击 解 答 显 示 其 内 容,2. Given two projections