Chapter 7: Plans and Elevations

7.1 Orthogonal Projections

Understanding Projections

• Orthogonal Projection: The image formed on a plane when light rays from an object hit the plane perpendicularly ($90^\circ$).
• Line Types in Drawings:
  • Solid Line (thick): Visible edges on the object.
  • Dashed Line (hidden line): Edges that are hidden from the viewer's sight line.
  • Thin Solid Line (construction line): Projection or grid alignment lines.

7.2 Plans and Elevations

Types of Views

• Plan: The orthogonal projection of a 3D object onto a horizontal plane as viewed from directly above (**Top View**).
• Front Elevation: The orthogonal projection onto a vertical plane as viewed from the front (**Front View**).
• Side Elevation: The orthogonal projection onto a vertical plane as viewed from the side (**Side View**, left or right).

Four-Quadrant Layout Grid

In standard KSSM technical drawing layout:

• Quadrant I (Top-Left): Side Elevation
• Quadrant II (Top-Right): Front Elevation
• Quadrant III (Bottom-Left): Plan (Top View)
• Quadrant IV (Bottom-Right): $45^\circ$ Construction Line for projection alignment.

7.3 Scale and Measurements

• All plans and elevations must be drawn to **full scale** ($1:1$) unless specified otherwise.
• Angles, parallel lines, and lengths on perpendicular planes must preserve actual object dimensions when projected onto orthogonal planes.