《平面立体的投影》ppt课件

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1、SummaryofPolyhedralSolids平面立体概述Prism棱柱Pyramid棱锥Exercise练习题ProjectionofPolyhedralSolids平面立体的投影请点击相应标题显示其内容SummaryofPolyhedralSolids平面立体概述Prisms棱柱Intersectionlinesofedgeplanesarecallededgelines.Intersectionlinesofedgeplanesandbasesarecalledbaseedgelines.Whendrawingprojectionsofpolyhedralsolids

2、,weareactuallydrawingtheprojectionsofalledgelinesandbaseedgelinesfollowedbyavisibilitytestoftheprojectededgelinesandbaseedgelines.各棱面的交线称为棱线,棱面与底面的交线称为底边,画平面立体的投影图,实质是画出所有棱线和底边的投影,并判别其可见性。Pyramids棱锥Polyhedralsolids平面立体请点击鼠标左键显示后面内容Polyhedralsolids:Thesolidsthataresurroundedbyplanesarecalledp

3、olyhedralsolids.平面立体:完全由平面围成的立体称为平面立体。Classbythebasesofprisms根据棱柱底面形状可分为:Triangularprism三棱柱Prism棱柱Squareprism四棱柱Pentagonalprism五棱柱Hexagonalprism六棱柱Drawsteps画图步骤：Drawcenterlinesanddatumlines.先画中心线和基准线;Addlinesfortheupperandlower(end)faces.再画反映顶部或底部(端面)形状的视图;Completethreeviews.按三等规律画全三视图。请点击鼠标

4、左键显示后面内容五棱柱的投影演示1.Projectionofaprism棱柱的投影……Example3.Drawthepentagonalprismandgetpointsonthesurface.画五棱柱及表面上各点的三视图。Theprojectionofpointisnotvisiblewhenitisoninvisibleedgeorplane.凡在不可见表面及棱线上的点,其投影则为不可见。Identification判别:Theprojectionofpointisalsovisiblewhenitisonvisibleedgeorplane.凡在可见表面及棱线上的点,

5、其投影为可见;Method方法:Gettingpointsonsurfacesofaprismcanbebasedontheaccumulationcharacteristicsofedgelinesorplaneprojection.棱柱表面上的点可利用棱线或棱面的积聚性投影求之。2.Gettingpointsonthesurfaceofaprism棱柱表面上取点Labeling标注:Allinvisiblepointsarewritteninbrackets.对不可见的点加括号以示区别。请点击鼠标左键显示后面内容Example1.Drawthetriangularprism

6、andgetpointsonthesurface.画三棱柱及表面上各点的三视图。Example2.Drawthesquareprismandgetpointsonthesurface.画四棱柱及表面上各点的三视图。Prism棱柱Classbythebasesofapyramid根据棱锥底面形状可分为:Triangularpyramid三棱锥1.Projectionofpyramid棱锥的投影Squarepyramid四棱锥Pentagonalpyramid五棱锥Hexagonalpyramid六棱锥Drawsteps画图步骤：1.Drawsymmetrylinesandtheb

7、aseofthepyramid.先画锥底面形状的投影;2.Addthevertexofthepyramid.再画锥顶点的投影;3.Completethreeviewsafteraddinglinesforthesidefaces.最后画各棱线的投影。请点击鼠标左键显示后面内容Pyramid棱锥……2.Gettingpointsonthesurfaceofapyramid棱锥表面取点AKEFDrawanauxiliarylineorplanegoingthroughthepointonthep