Aisle Width Validation

Event venues are usually subject to a minimum aisle width — enforced by the venue, the fire marshal, or the show organiser. PlanCAD's aisle width validator measures the actual gap between every pair of stands on the plan and flags any aisle that is narrower than your threshold.

What It Does

Given two parameters — a minimum aisle width and an ignore-below threshold — the tool:

1. Collects every visible closed shape that could form a stand: rectangles and closed polylines.
2. Compares all pairs of shapes and computes the minimum distance between them, accounting for rotation.
3. Skips pairs whose bounding boxes are further apart than the minimum width (a fast spatial reject).
4. Skips corner-to-corner gaps (the quincunx pattern between four neighbouring stands is not a real aisle).
5. Skips gaps smaller than the ignore-below threshold — these are touching or near-touching stands, not aisles you can correct by widening.
6. Reports every remaining gap that is wider than the ignore-below threshold but narrower than the minimum width.

Violations are stored on the project (and persisted in the .plancad file) and drawn as red highlight segments connecting the two closest points of each offending pair.

Running the Validator

1. Open Analyse > Validate aisle widths… from the menu bar.
2. Fill in the dialog:
   • Minimum aisle width — the threshold below which an aisle is considered narrow. Defaults to your last-used value, or 2 units the first time. Units follow the active drawing unit (mm, cm, m).
   • Ignore if less than — gaps smaller than this are skipped entirely. Defaults to 0.5. Use this to skip stands you have deliberately placed back-to-back.
3. Click OK. PlanCAD shows a "Calculating…" toast, then either:
   • A green success toast — "All aisles meet minimum width (X units)" — when the plan is clean.
   • A warning toast — "N narrow aisle(s)" — and overlays red segments between each offending pair.

Distances are rounded to centimetre precision (two decimals). A gap of 1.999 m rounds to 2.00 m and passes if your minimum is 2 m.

Reading the Overlay

Each violation is rendered as a short red line connecting the two closest points of the offending stand pair, with the rounded gap value displayed alongside. The overlay sits above stands but below selection highlights.

When the validator finds at least one violation, a Visualizations row labelled "Aisle widths" appears at the bottom of the Layers panel. It exposes:

• Visibility toggle — show or hide the overlay without re-running the analysis.
• Opacity slider — fade the overlay so you can compare it against the bare drawing.
• Remove button (×) — clears the validation result.

The 3D view picks up the same overlay state, so violations are visible when reviewing the plan in 3D as well.

Algorithm Notes

• Shape collection — only rectangles (with rotation) and closed polylines with at least three vertices are eligible. Circles, ellipses, hatches, and open polylines are ignored. The rationale is that only entities whose footprint is a clear polygon are considered "stands" for the purposes of aisle measurement.
• Bounding box reject — for each pair, PlanCAD computes a fast AABB-to-AABB distance and skips the pair if it already exceeds the minimum width. This makes the validator near-linear on plans where most stands are far apart.
• Edge-to-edge distance — for every surviving pair, PlanCAD projects each endpoint of every edge onto the other shape's edges and also checks for true segment-segment intersection. Touching or overlapping shapes return a distance of 0 (and are filtered by the ignore-below threshold).
• Corner-to-corner filter — when the closest pair of points falls on two vertices rather than two edge interiors (a quincunx pattern: four stands meeting diagonally), the gap is not a real aisle and is skipped. This is the most common source of false positives in dense layouts.

Tips

• The validator is purely geometric — it does not consider entrance markers or pedestrian flow. Pair it with the Pedestrian Flow Heatmap to identify aisles that are both narrow and heavily used: those are the real congestion risks.
• If you regularly work to a fixed venue spec, the dialog remembers the last values you used, so subsequent runs are a two-click operation.
• Want to enforce different minima for different zones? Filter the drawing using layer visibility before running the validator. Hidden entities are not considered.
• The aisle violation set is part of the persisted project state — closing and reopening a .plancad file preserves the overlay until you clear it or rerun the validator.