Amogh N P
✦ In loving memory of Amogh N P — Architect · Designer · Visionary ✦
An Indian architecture student drafting a floor plan on a CAD workstation.
Unit IArchitectural Graphics & Computer Studio

Drafting Basics

From the board to the screen — and the language of symbols.

≈ 35 min

Drawing has moved to the screen — but the discipline has not changed. Digital drafting is the same precise, conventional drawing you learned on the board, only the geometry now lives in the computer as editable objects you can move, copy and measure. This first lesson sets up what CAD really is, the one habit that underlies everything, and the graphic language your drawings speak.

Learning objectives

By the end of this lesson you will be able to — mapped to the course outcomes for Architectural Graphics & Computer Studio:

1
CO1 · Understand

Explain what CAD is — and correct the common myths about it.

2
CO1 · Understand

Distinguish vector (object) drawing from raster (pixel) images.

3
CO1 · Apply

Adopt the core habit — draw geometry at full size (1:1) in model space.

4
CO1 · Apply

Represent doors, windows, materials and glass with standard symbols and hatches.

What CAD is — and isn't

From the board to the screen

CAD is a category of tools, not a single program, and it drafts and documents — it does not design for you. It is the digital companion to the by-hand Architectural Graphics I conventions. Select a topic.[1, 2, 7]

Computer-aided drafting & design

CAD is using a computer to create, modify and document drawings — geometry stored as precise, editable objects rather than ink on paper. It is a category, not a single program: 2-D drafting (AutoCAD, DraftSight, the open-source LibreCAD/QCAD) and the BIM/3-D modellers (Revit, ARCHICAD, Vectorworks) are all CAD. The tool drafts and documents; it does not design for you.[1, 7]

From the board to the screen drawing board + T-square CAD workstation Same precise drawing — but the geometry now lives as editable vectors you can move, copy and measure.
DiagramA drafting board and T-square giving way to a CAD workstation
Objects, not pixels Vector — a CAD drawing a curve = coordinates + equation sharp at any zoom · editable Raster — a photo or scan a grid of fixed pixels blurs / blocks up when enlarged You draft in vector; the site photographs you place are raster.
DiagramA vector curve made of objects compared with the same curve as raster pixels
The two core ideas

Vector, not pixels — and full size

A CAD drawing is made of vector objects defined by coordinates and equations, not a grid of pixels — so it stays sharp at any zoom and every line can be edited. And you always draw at full real-world size (1:1) in model space; scale comes only at the plot.[3, 5]

AspectVector — a CAD drawingRaster — a photo or scan
Made ofObjects — lines, arcs, polylines (coordinates + equations)Pixels — a fixed grid of coloured dots
On zoomStays sharp at any magnificationBlurs / pixelates when enlarged
EditableEach entity moved, trimmed, measuredOnly the pixels; no separate objects
Typical useDrafting — plans, sections, detailsPhotographs, scans, site images
FilesDWG (native), DXF (interchange)JPEG, PNG, TIFF
Draw at full size (1:1) in model space X Y origin 0,0 3000 units = 3.000 m one CAD unit = one millimetre Never scale the geometry. A 3 m wall is 3000 units long — scale is applied only later, at the plot.
DiagramA wall drawn at full size in model space with X and Y axes from the origin
Symbols & hatches (IS 962)

The graphic language

Plans are read by convention. Doors carry a swing arc, windows a wall break, stairs an up-arrow; sections, levels and north points orient the reader; and material hatches name what is cut. IS 962 standardises these for India.[6, 4]

The graphic language (IS 962) door + swing window stair (up) N north point AA section / cutting plane 1A1 detail callout +3.000 level / datum Plans are read by convention — the same symbols mean the same thing on every desk.
DiagramA legend of standard architectural symbols — door, window, stair, north point and section marker
Materials by pattern (IS 962) brick concrete earth timber (grain) steel (solid) glass A section is filled with the hatch that names its material — keep hatches on their own layer.
DiagramStandard material hatch patterns for brick, concrete, earth, timber, steel and glass
A CAD workstation — a line drawing on screen beside a printed sheet.
PhotoA CAD workstation — a line drawing on screen beside a printed sheet.
A printed legend sheet of door, window and sanitary symbols.
PhotoA printed legend sheet of door, window and sanitary symbols.
A drawing detail filled with material hatches — brick, concrete, earth.
PhotoA drawing detail filled with material hatches — brick, concrete, earth.
An Indian architecture student drafting a floor plan on a CAD workstation.
PhotoAn Indian architecture student drafting a floor plan on a CAD workstation.
Check your understanding

Self-assessment

1. In CAD, you should draw a 4-metre wall as:

2. The key difference between a vector drawing and a raster image is:

3. ‘CAD = AutoCAD’ is:

In a nutshell

Recap

CAD is a category — drafting and documentation tools, not a designer; AutoCAD is one program among many.
Drawings are vector (editable objects); photographs are raster (pixels).
The core habit: draw at full size (1:1) in model space — scale only at the plot.
Speak the graphic language — door swings, window breaks, north points and IS 962 material hatches.
The evidence

References & further reading

  1. [1]Best 2D and 3D CAD drafting software — the CAD landscape (AutoCAD, DraftSight, LibreCAD, Revit, ARCHICAD). First In Architecture. https://www.firstinarchitecture.co.uk/best-2d-and-3d-cad-drafting-software/
  2. [2]AutoCAD — origin and history (Autodesk founded 1982; AutoCAD 1.0 shipped December 1982). Wikipedia. https://en.wikipedia.org/wiki/AutoCAD
  3. [3]Raster (bitmap) vs vector graphics — objects vs pixels, resolution independence. Overview. https://en.wikipedia.org/wiki/Vector_graphics
  4. [4]Architectural graphics 101 — standard symbols (doors, windows, sections, north point). Life of an Architect. https://www.lifeofanarchitect.com/architectural-graphics-101-symbols/
  5. [5]Drawing scale explained — draw at 1:1 in model space, scale at plot. AutoCAD Tips. https://autocadtips.com/blog/drawing-scale-explained-model-at-1-1-vs-plot-scale/
  6. [6]IS 962:1989 — Code of practice for architectural and building drawings (symbols & conventional representation of materials). BIS. https://law.resource.org/pub/in/bis/S03/is.962.1989.pdf
  7. [7]Sketchpad — Ivan Sutherland's pioneering interactive-graphics system (MIT, 1963). Britannica. https://www.britannica.com/technology/Sketchpad

Further reading

  • Ching, F.D.K. (2023). Architectural Graphics (7th ed.). Hoboken, NJ: Wiley. ISBN 978-1-394-20626-1 — the graphic conventions and symbols.
  • Onstott, S. (2014). AutoCAD 2015 and AutoCAD LT 2015 Essentials. Indianapolis: Autodesk Official Press (Sybex/Wiley).
  • Uddin, M.S. (1999). Digital Architecture. New York: McGraw-Hill — drawing in the digital medium.

Sources gathered and fact-checked June 2026. Published values vary by source, sample and method — treat as indicative and confirm against the cited standard before structural use.

Architectural Graphics IThe by-hand conventions CAD automates — learn the grammar first.