# ISO 5456-4-1996

Disclosure to Promote the Right To InationWhereas the Parliament of India has set out to provide a practical regime of right to ination for citizens to secure access to ination under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this ination in an accurate manner to the public. “ -”Satyanarayan Gangaram Pitroda“Invent a New India Using Knowledge”“01 5 ”Jawaharlal Nehru“Step Out From the Old to the New”“1 , 1 ”Mazdoor Kisan Shakti Sangathan“The Right to Ination, The Right to Live”“ 0 B ”BharthariNtiatakam“Knowledge is such a treasure which cannot be stolen”IS 15021-4 2001 Technical Drawings - Projection s,Part 4 General Projection PGD 24 DrawingsIS 15021 Part 4 2001ISO 5456-41996Indian StandardTECHNICAL DRAWINGS PROJECTION SPART 4 CENTRAL PROJECTIONIcs 01.100.01 BIS 2001BUREAU OF IN DI AN STAN DARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARGNEW DELHI 110002December 2001 Price Group 11Drawings Sectional Committee, BP 24NATIONAL FOREWORDThis Indian Standard Part 4 which is identical with ISO 5456-4 1996 Technical drawings Projection s Part 4 Central projection issued by the International Organization forStandardization ISO was adopted by the Bureau of Indian Standards on the recommendation ofDrawings Sectional Committee and approval of the Basic and Production Engineering DivisionCouncil.This standard Part 4 specifies basic rules for the development and application of central projection intechnical drawings. Other parts of this series are given as followsIS 15021 Part 1 2001 Technical drawings Projection s Part 1 SynopsisIS 15021 Part 2 2001 Technical drawings Projection s Part 2 OrthographicrepresentationsIS 15021 Part 3 2001 Technical drawings Projection s Part 3 AxonometricrepresentationsThe text of ISO Standard has been approved as suitable for publication as Indian Standard withoutdeviations. In the adopted standard certain terminology and conventions are not identical to thoseused in Indian Standards. Attention is particularly drawn to the followinga Wherever the words International Standard appear referring to this standard, they should beread as Indian Standard.b Comma , has been used as a decimal marker, while in Indian Standards, the currentpractice is to use a full point . as the decimal marker.In this adopted standard, reference appears to the following International Standard for which IndianStandard also exists. The corresponding Indian Standard which is to be substituted in its place islisted below along with its degree of equivalence for the edition indicated International Corresponding Degree ofStandard Indian Standard EquivalenceISO 10209-21993 IS 8930 Part 2 2001 Technical product Identicaldocumentation Vocabulary Part 2Terms relating to projection sThis adopted standard also gives Bibliography in Annex B which is inative. The correspondingIndian Standard against the ISO Standard is given below along with their degree of equivalence forthe editions indicated/nternationa/ Corresponding Degree ofStandard Indian Standard EquivalenceISO 5456-11996 IS 15021 Part 1 2001 Technical Identicaldrawings Projection s Part 1SynopsisISO 5456-21996 IS 15021 Part 2 2001 Technical dodrawings Projection s Part 2Orthographic representationsISO 5456-31996 IS 15021 Part 3 2001 Technical dodrawings Projection s Part 3Axonometric representationsISO 10209-11992 IS 8930 Part 1 1995 Technical product dodocumentation Vocabulary Part 1Terms relating to technical drawingsGeneral and types of drawings firstrevisionIS 15021 Part 4 2001ISO 5456-41996Indian StandardTECHNICAL DRAWINGS PROJECTION SPART4 CENTRAL PROJECTION1 ScopeThis part of 1S05456 specifies basic rules for thedevelopment and application of central projection intechnical drawings.2 Normative referenceThe following standard contains provisions which,through reference in this text, constitute provisions ofthis part of ISO 5456, At the time of publication, theedition indicated was valid. All standards are subjectto revision, and parties to agreements based on thispart of ISO 5456 are encouraged to investigate thepossibility of applying the most recent edition of thestandard indicated below. Members of IEC and ISOmaintain registers of currently valid internationalStandards.ISO 10209-21993, Technical product documentation Vocabulary Part 2 Terms relating to projections.3 DefinitionsFor the purposes of this part of ISO 5456, the defi-nitions given in ISO 10209-2 and the foHowing defi-nitions apply.3.1 alignment line Line parallel to a given linepassing through the projection centre. Its intersectionwith the projection plane gives the vanishing point ofall lines parallel to the given line.3.2 height of projection Vertical distance of theprojection centre from the basid plane.3.3 horizontal distanca Distance between theprojection centre and the projection plane.3.4 projection angle Angle ed by the projec-tion plane and the horizon plane.3.5 scale point Vanishing point of the horizontaldirection orthogonal to that bisecting the angle edby the horizon line and the alignment line of the givenhorizontal line, and allowing the true length of theprojection of the given line to be determined.3.6 station of observation Orthogonal projectionof the projection centre onto the basic plane.1.4IS 15021 Part 4 2001ISO 5456-419964 SymbolsLetter symbols for terms used in central projectionare given in table 1 and illustrated in figures 1 and 2,as well as in the figures mentioned in table 1.Table 1 LattarsymbolsNo. Term Letter symbol Figura1 Projection plane T 11 Basic plane G 11 Basic line x 13.4 Projection angle P 51 Horizon plane HT 11 Horizon line h 13.1 Alignment line VI 41 Main point c 11 Vanishing point v 41 Main projector pL 11 Projection centre o 13.2 Height of projection H 13.3 Horizontal distance d 11 Vision cone K 21 Circle of vision Ks 31 Vision angle a 21 Projector PI 31 Distance point DP 133.5 Scale point MP 143.6 Station of observation Sp 11 Terms already defined in ISO 10209-2.5 CentralprojectionsThe mode of the central projection depends on theposition of the object to be represented with respectto the projection plane.For possible positions and applicable projections, see 5.1 to 5.4.5.1 One-pointA one-point projection is a central projectionof an object having its principal face parallel to theprojection plane special position. All parallel outlinesand edges of the object which are parallel to theprojection plane retain their direction in this represen-b.,. f.tation horizontal lines remain horizontal and vertical ,;90”, 3tha vanishing point for vertical lines is situated belowthe horizon line see figure 5 and 7.5.1 and 7.5.2.5.4 CoordinateRepresentation by the coordinate is based onsimple proportions.The coordinates, related to the main projector of allrelevant points of the object to be represented, aretaken by the graphic from the basic plane andelevation. From these point coordinates, the imagecoordinates are obtained by a calculation andentered to scale. The image points are connected toeach other to provide a clear representation of theobject see figure 6.6 Principle6.1 LocationandpositionoftheprojectionplaneThe image size of an object can be varied by parallelshifting of the projection plane. If the object is placedin front of the projection plane, the representation willbe enlarged. The object behind the projection planewill result in a smaller image. Figure 7 shows thechange in image size depending on the position of theobject with respect to the projection plane.Figure 8 shows the change in image size dependingon the of representation with vertical orinclined projection planes. /3 is the included anglebetween the projection plane and the basic plane nearthe projection centre.2IS 15021 Part 4 2001ISO 545641996Figure1 Projectionmodal of the centralprojectionIS 15021 Part4 2001ISO 5456-41996xFigure2 Wion coneand viaionanglein the projectionmodal of the centralprojectionIJc900Figure7 Locationof projectionplanes Figure8 Positionof projectionplanesIS 15021 Part 4 2001ISO 5456-4 19966.2 Circle of vision and vision cone instructive since length, width and height do notmatch the objects inherent proportions see figure 9.To obtain a fully instructive image of an object withoutperipheral distortions on the projection plane, the An object can be depicted nearly undistorted if theobject must be positioned within a vision cone having projectors result in a bundle of rays inclined not morean aperture angle not greater than 60. than 30 with respect to the main projector. At thisHeavy peripheral distortions occur on images outside aperture angle the vision cone provides only a smallthe circle of vision; the image does not appear fully distortion on the projection plane./4To Tfuiho. “b “ ““””,,paim J C I“-“-lW ,1 ““RI ISpFigure9 Object, framed in a cube,within and outsidethe circleof vision8The main projector should hit the object to be de-picted in a part which is visually important, so that theobject is contained within the minimum vision cone.6.3 DistanceDifferent relative distances influence the image size andits appearance. When the distance between the objectand the projection plane is fixed and the projection centreand the object lie on opposite sides of the projectionplane, increasing the distance d between the projectioncentre and the projection plane gives enlarged andflattened representations. When the distance d is fixedand the object and the projection centre lie on oppositesides of the projection plane, increasing the distanceIS 15021 Part 4 2001 --qISO 5456-41996i,,t1between the object and the projection plane gives rcduced and flattened representations.,7 Principlesand s of depiction17.1 Piercing f,,,Using the piercing , the piercing points ofprojectors with the projection plane are shown bybasic plane and elevation, and may be determinedeither by drawing or by calculation see figure 10.The piercing allows even complex objectsround shapes, helicoids, etc. to be easily repre-sented in central projection.h. .Figure10 projectionmodalturned intothe drawingsurfacewith sideview9IS 15021 Part 4 2001ISO 5456-419967.2 Trace point vanishing point sWith the trace point vanishing point s, theoutlines and edges of the object to be depicted areimaged from basic plane and elevation.7.2.1 Tracepoint vanishingpoint Aspecial position of the objectIn A, one vertical face of the object is parallelto the vertical projection plane special position of theobject with respect to the projection plane, so thatthe vanishing point for those edges parallel to theprojection plane is situated at infinity and the vanish-ing point for those edges perpendicular to the projec-tion plane is the main point see figure 11.7.2.2 Tracepoint vanishingpoint Bparticular position of the objectIn B, horizontal faces of the object are per-pendicular to the vertical projection plane particularposition of the object with respect to the projectionplane so that the lines are represented by their traceon the projection plane and by their vanishing pointsee figure 12.I ---.1c Mz ,,a/ /1;G ,x ; ,--“” 1T.-_ ____ _ _,--_ f_--f_;--./.f_;m1P1 u/2Sp,Figure11 Object,framed in a cubeindicatedby a double-dashedline,in specialpositionwith respectto the projectionplaneaccordingto A10IS 15021 Part 4 2001ISO 5456-41996IjZ,, 90 to be depicted moves below the horizon line frominfinite to finite, so that tilting projected vertical linesDue to the inclination away from the projection cen- provide an optical distortion suggesting a taperingtre, the vanishing point for vertical lines of the object see figure 16.P-1v v, JSp3c“--------//./l-h v 0//,-/.”v2//Figure16 Object,framed in a cube indicatedby a double-dashedline,in front of a projectionplaneinclinedaway from the projectioncentre15IS 15021 Part4 2001ISO 5456-419967.6 Coordinate piercing The coordinate piercing is based on simpleproportions, in which each piercing point of the pro-jectors in the projection plane is not established bydrawing, but by calculation. This is based ondividing the space in four quadrants by two referenceplanes, one horizontal and one vertical, each perpen-dicular to the projection plane, their common linebeing the main projector. The common lines of thehorizontal and vertical reference planes and the pro-jection plane are the X and Y axes of a rectangularCartesian coordinate system situated in the projectionplane, the origin of which is the main point. Theprojector is positive negativewhen Al is above below the main projector.8 Developmentof a centralprojectionBy turning the basic plane into the projection planesee figure 1, it is possible to present the represen-tation of the basic plane on the drawing surface andsubsequently to create the complete representationof the dimensions taken from the elevation.There are two different ways to turn the basic plane.“.Figure17 Coordinatepiercing16IS 15021 Part4 2001ISO 5456-419968.1 Turning the basic plane downwards 8.2 Turning the projection plane downwardsThe station of observation, Sp, is placed at thedistance d from C, below the basic line X. The The basic line becomes the axis of symmetry. Thisfrequently-used arrangement saves space on therepresentation is above, and the basic plane is below drawing surface and is called economy arrangementthe basic line; they do not cover each other. This see figure 19.arrangement is caled regular arrangement and givesthe best survey, but requires considerable space onthe drawing surface see figure 18.,,L-,xi“1__txlPLP1 6i”Ks,_ ------ _________ ____lIiIiiiia -ch -,1J- -- ------ ---------- __ -;---- - 1Y/z-.-l-eQ/2SpFigure18 Regulararrangementthe representation is placed above the basic line X-Figure19 Economyarrangementthe perspective representation is placed below the basic line X17aIS 15021 Part 4 2001ISO 5456-4 1996Annex AinativeExamples for comparison of different depiction sThe following figures A.1 to A.17 illustrate some of the different depiction meth