3D to 2D Orthographic Projection Delineation Techniques Clipping Plane Methodology
Graphical Representation • The vast majority is 2D representation of 3D objects • Technical Documentation – Construction Documents, basic communication with peers • 3D conception –> 2D representation –> 3D realization • Computer Models can be “photographed” – images and line drawings can be generated much faster than can be drawn • Extraction Methodology – design in 3D, extract 2D
Orthographic Projection • A means of representing a three-dimensional (3D) object in two dimensions (2D) • A perspective projection with a hypothetical viewpoint—e.g., one where the camera lies an infinite distance away from the object and has an infinite focal length, or "zoom". (parallel projection) • Multi-view Orthographic Projection • Axonometric Orthographic Projection Non-Orthographic (Perspective) Orthographic
Multi-View Orthographic • Each projection plane is parallel to one of the coordinate axes of the object resulting in visual distortion / abstraction
Architectural Plan • Also called plan view. a drawing made to scale to represent the top view or a horizontal section of a structure
Architectural Section • A representation of an object as it would appear if cut by a plane, showing its internal structure.
Architectural Elevation • A drawing or design that represents an object or structure as being projected geometrically on a vertical plane parallel to one of its sides.
Axonometric • Axonometric • A skewed Orthographic Projection so that multiple sides are visible at once • a three-dimensional object is represented by a drawing having all axes drawn to exact scale, resulting in the optical distortion of diagonals and curves • Trimetric – arbitrary foreshortening • Isometric
Isometric • a three-dimensional object is represented by a drawing having the horizontal edges of the object drawn usually at a 30° angle and all verticals projected perpendicularly from a horizontal base, all lines being drawn to scale
Clipping Planes • Uses Orthographic Cameras – Relatively Universal • Extracts from solids or surfaces alike • Uses two planes perpendicular to the focal length of the camera – Near Clipping Plane and Far Clipping Plane • Only displays graphical information between the near clip and the far clipping plane
Plotting to File with Clipping Planes • The clipping plane method can be used in conjunction with the plot to file method. Plotting to file allows three important options in a single method – • Allows rendering – allows the use of hidden line projection to “hide” lines that should be obscured with planes in 3D space. • Flattens the drawing – gets rid of the Z dimension and flattens the 3D model to a 2D vector drawing • Separates the line drawings – Drawings can be edited in respect to themselves without adversely altering the model
Plotting to File with Clipping Planes – AutoCAD Method • Import the 3D model • Page Setup Manager for a real-scale vector file • Set up the layout for the desired view • View • Scale • Use clipping planes to “cut” • Use hidden line rendering on the viewport • Plot to file • Import plotted file into a [new] drawing • Make it pretty • Poche • Entourage • Line weight
Plotting to File with Clipping Planes • 3 datasets to manage • Original model file • Multiple layouts preferably – one for each “view” • Vector files (DXB) • Individual plot files with extensions that are not .dwg. • These are not opened, but imported • The Presentation file • All vector files are imported here for cleanup and delineation