第3章平面立体的投影

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2SummaryofPolyhedralSolids平面立体概述Prisms棱柱Intersectionlinesofedgeplanesarecallededgelines.Intersectionlinesofedgeplanesandbasesarecalledbaseedgelines.Whendrawingprojectionsofpolyhedralsolids,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:Thesolidsthataresurroundedbyplanesarecalledpolyhedralsolids.平面立体:完全由平面围成的立体称为平面立体。3Classbythebasesofprisms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。请点击鼠标左键显示后面内容五棱柱的投影演示1.Projectionofaprism棱柱的投影……4Example3.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,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.Drawthetriangularprismandgetpointsonthesurface.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5Classbythebasesofapyramid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.Drawsymmetrylinesandthebaseofthepyramid.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……62.Gettingpointsonthesurfaceofapyramid棱锥表面取点AKCBPEFDrawanauxiliarylineorplanegoingthroughthepointonthepyramid.在棱面上过锥顶作一条包含该点的辅助线或辅助平面。Distinguish判别: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Example4.Drawaregulartriangularpyramidandgetpointsonthesurface.画正三棱锥及表面上各点的三视图。Example5.Drawaregularpentagonalpyramidandgetpointsonthesurface.画正五棱锥及表面上各点的三视图。Pyramid棱锥Theprojectionofpointisalsovisiblewhenitonvisibleedgeorplane.凡在可见表面及棱线上的点,其投影为可见；Theprojectionofpointisnotvisiblewhenitoninvisibleedgeorplane.凡在不可见表面及棱线上的点,其投影则为不可见。Method方法:7aExercise.Completeeachdrawingbyaddingthemissingdetail.补全平面立体及其表面上各点的三投影。（1）Drawaprismandgetpointsonthesurface.画三棱柱及各点的三投影。c'a'(b')aab(c)cb（2）Drawapyramidandgetpointsonthesurface.画五棱锥及各点的三投影。abca'b'c请点击解答显示其内容(c')(b)本小节结束谢谢您的认真学习！退出前一页9ABExample1.Drawthetriangularprismandgetpointsonthesurface.画三棱柱及表面上各点的三视图。(b)aSDrawviewoftheendfaces.先画反映端面形状的视图;Completethreeviews.再按三等规律画全三视图;Drawallviewsofpoints.求各点的三投影。请点击鼠标左键显示后面内容Steps作图步骤：aa'(b')b10dcdCDSExample2.Drawthesquareprismandgetpointsonthesurface.画四棱柱及表面上各点的三视图。请点击鼠标左键显示后面内容Drawviewoftheendfaces.先画反映端面形状的视图;Completethreeviews.再按三等规律画全三视图;Drawallviewsofpoints.求各点的三投影。Steps作图步骤：cd'（c)11FESExample3.Drawthepentagonalprismandgetpointsonthesurface.画五棱柱及表面上各点的三视图。Steps作图步骤：（1）Drawtheaccumulationtopview.先画有积聚性的俯视图;（2）Drawthelimitelements.再画主视图各棱线的投影;（3）Drawallviewsofprism.根据投影规律求第三投影;（4）Drawallviewsofpoints.求各点的三投影。请点击鼠标左键显示后面内容e'e（f)f'fe12KCABEDa'b'c'Steps作图步骤：acbk1＇1SExample4.Drawaregulartriangularpyramidandgetpointsonthesurface.画正三棱锥及表面上各点的三视图。（1）Drawthetopview.先画俯视图;（2）Drawthelimitelements.再画主视图各棱线的投影;（3）Drawallviewsofpyramid.根据投影规律求第三投影;（4）DrawallviewsofpointD.用辅助素线法求D点的三投影;（5）DrawallviewsofpointE.用辅助平面法求E点的三投影。P请点击鼠标左键显示后面内容a(c)bd'（d)e'eedkk'p'p13DEABCKFGExample5.Drawaregularpentagonalpyramidandgetpointsonthesurface.画正五棱锥及表面上各点的三视图。bkdaecSfSteps作图步骤：1）Drawthetopview.先画俯视图;2）Drawthelimitelements.再画主视图各棱线的投影。3）Drawallviewsofpyramid.根据投影规律求第三投影;4）DrawallviewsofpointG.求G点的三投影(用棱线法)。5）DrawallviewsofpointF.求F点的三投影(用辅助平面法)。请点击鼠标左键显示后面内容g'g（f)f'gb'(a')c'(e')d'a(e)b(d)ckk'p'p1415在图片上点击鼠标左键可以“暂停”或再次“播放”16在图片上点击鼠标左键可以“暂停”或再次“播放”17在图片上点击鼠标左键可以“暂停”或再次“播放”