Revit Automatic Dimensions

Automatic Dimensions — Swich Design pyRevit Extension

Short demo : https://youtu.be/v7vOXhg8PAg

Open-source pyRevit extension that codifies US construction-document dimensioning conventions as an auditable, deterministic rule engine — no AI in the placement logic.

What it does

One button — Automatic Dimensions (pyRevit tab → Drawing Set panel), one dialog, two modes:

• Exterior — select the perimeter walls of a level; the tool chains them, groups them by facing direction (angled wings get their own correctly-rotated frames), and places a stacked 3-tier string per side: jogs + openings / jogs only / overall. First-string offset and tier spacing are configurable in paper inches, with per-view-scale presets. On large multi-mass plans, sides split automatically so witness lines never cross another selected wall. (The wall type's Function parameter is deliberately ignored — it is unreliable in real models, so exterior mode always works from your selection.)
• Interior — driven entirely by placed Rooms: room lengths on both axes (placed at the room's quarter lines), one opening string per room wall with doors/windows, and center-to-nearest-wall dimensions for fixtures, casework and columns.

Both modes: measure to finish faces or calibrated core (stud) faces; openings to centreline or rough-opening jambs; dry run prints a full report with zero model changes; every skipped or failed string is reported by name — nothing fails silently.

Out of scope for v1: curved walls (skipped with a note).

Architecture

SwichDesign.extension/
├── lib/autodimswichdesign/
│   ├── geometry.py    pure Python rule math — no Revit imports, unit-tested
│   ├── standards.py   dimensioning constants (paper-space, × View.Scale)
│   └── revit_io.py    ALL Revit API touchpoints (extraction + placement)
└── pyRevit.tab/Drawing Set.panel/Automatic Dimensions.pushbutton/
    ├── script.py           IronPython button: UI + orchestration only
    ├── AutoDimWindow.xaml  the WPF dialog
    ├── bundle.yaml         localised title/tooltip (8 locales)
    ├── icon.png            light theme
    └── icon.dark.png       dark theme

The tab/panel folders deliberately mirror pyRevit's own names (pyRevit.tab, Drawing Set.panel), so the button merges into pyRevit's existing Drawing Set panel rather than creating a tab of its own — pyRevit merges panels by name (loader/uimaker.py calls create_ribbon_panel(..., update_if_exists=True)).

Loading the extension

pyRevit tab → Settings → Custom Extension Directories → add this repo's root folder (the one containing SwichDesign.extension) → Save → Reload.