ASME Y14.3-2012 pdf download.Orthographic and Pictorial Views Engineering Drawin.
4 PICTORIAL VIEW CREATION This Section provides requirements for pictorial views used in a drawing graphic sheet when those views are constructed or generated from the models or design mod- els defned by ASME Y14.41. Alternatively, pictorial view requirements are explained in terms related to drawing (view construction) practices such as projection lines and viewing planes. Unless otherwise specifed, the resulting view requirements apply equally to constructed views and views generated from models and design models.
4.1 Pictorial Views A pictorial view is the fgure outlined upon the view- ing plane by lines of projection extending from an object when that object may be at angles other than parallel to the viewing plane. The projection lines may be per- pendicular to the viewing plane, or may, as in the case of perspective views, emanate from a viewing point. Constructed pictorial views generally do not show the true shape of all features. A pictorial view is created using one of the projection systems specifcally delineated in this Standard. This includes the selection of the method of projection and the appropriate specifcation of parameters to link to an associated CAD model to enable reproduction of the view when requested. Pictorial view requirements contained in this Standard apply equally to constructed views and saved views in drawing graphic sheets unless exception is stated. See para. 4.2.4. In general, constructed views include the use of drawing conventions that may not be true geometry. Conversely, saved views generally contain true shape and true size geometry.
4.2.1 Axonometric Projection. An axonometric pro- jection is one in which the projectors are perpendicular to the plane of projection and parallel to each other. The principle surfaces and edges of a cube or other rectan- gular object are all inclined to the plane of projection. The angles between the principle edges or axes of the object shall not measure 90 deg on the viewing plane. The relationship between the three angles shall be such that the apparent mutual perpendicularity of the axes on the object is maintained. See Figs. 4-2 through 4-5. The view direction should be one that gives the most information about the object unless other considera- tions, such as natural position or relation to other objects, take precedence. It should be noted that an axonometric projection can be obtained by constructing a secondary auxiliary view in which the desired line of sight appears as a point, or by revolving the object into the desired position and drawing a front view or other principal view. Axonometric projection methods are divided into isometric, dimetric, and trimetric projections.ASME Y14.3 pdf download.