Thiết kế flash - Multiview projections 1

Multiview Projections 1Glass Box TheorySome CharacteristicsParallel projectorsProjectors normal to projection planeObject positioned with one face parallel to projection planePEBProjectorsPPOnly one face visible  need more than one view to describe object Glass Box Theory - 1Mutually perpendicular projection planes (sides of glass box)Position object inside glass box. PEB orthogonal to sides of glass boxSix principal views (front/back, top/bottom, left/right)Frontal (F), Horizontal (H), Profile (P) projection planesObject dimensions (width, height, depth)Hinges – fold lines (H/F, F/P)Glass Box Theory - 2Images projected onto the projection planes Glass Box Theory - 3Sides of glass box hinged (H/F, F/P) so that when opened Glass Box Theory - 4the views are aligned as shown here:Glass Box Theory - 5View Alignment/View PlacementArrangement of ViewsTop and Front are vertically aligned, share width dimensionFront and Right are horizontally in line, share height dimensionTop and right are not aligned, share depth dimensionTransfer of DepthEvery point or feature in one view must be aligned on a parallel projector in an adjacent / related view Line ConventionsVisible lines – used to represent visible edges on an partCenter Lines – used to identify centers of circles and axes of cylinders (holes). Also used to identify symmetry and to show path of motionAlphabet of linesMultiview Drawing of a CylinderCenterlines only cross in circular viewExtend center lines about 5mm past object edgeNOTE: Limiting elements refer to the extents of a curved surface. In engineering graphics lines are use to represent limiting elements, just as they are used to represent edges.edgelimiting elementHidden LinesHoles – locate limiting elementsSurfaces – locate edge view of a surfaceChange of planes – locate position of a change of plane or a corner Hidden lines are used to show hidden features (e.g., edges, limiting elements, etc.) on an objectMultiview Projections 1This is the end!