This article explains how to detect walls from Point Cloud floor plan slices in ARCHLine.XP and use the detected geometry for BIM reconstruction workflows.

Wall detection is often the first major step in Scan-to-BIM workflows because it transforms raw Point Cloud information into architectural wall geometry that can be used for:

BIM modeling,
renovation projects,
floor plan reconstruction,
and existing building documentation.

The wall detection workflow uses horizontal Point Cloud slices to identify wall positions and generate wall elements or reference geometry.

Recommended Preparation Steps

Before starting wall detection:

crop unnecessary regions,
isolate the active floor,
reduce excessive point density,
remove visible clutter,
and optimize visibility filters.

Important:
Furniture, vegetation, and overlapping scans may interfere with detection accuracy.

Creating a Floor Plan Slice

A floor plan slice is a thin horizontal section of the Point Cloud used to visualize wall geometry.

The slice isolates wall regions at a selected height while hiding unnecessary vertical information.

This creates a clear 2D representation of the building layout.

Choosing the Correct Slice Height

The slice height is critical for successful detection.

Recommended slice position:

slightly above floor level,
typically intersecting wall bodies,
below windows when possible.

Avoid:

ceiling regions,
window openings,
cluttered furniture zones.

Slice Thickness

Slice thickness determines how much vertical geometry is included.

Thin Slices

Advantages:

cleaner wall outlines,
reduced clutter,
improved line readability.

Disadvantages:

incomplete wall visibility if the slice is too thin.

Thick Slices

Advantages:

more complete geometry.

Disadvantages:

overlapping objects,
increased noise,
reduced detection precision.

Recommended approach:
Use the thinnest slice that still preserves continuous wall geometry.

Starting Wall Detection

After preparing the floor plan slice, start the wall detection workflow in ARCHLine.XP.

For parallel walls:

The algorithm searches the point cloud for parallel wall planes with high accuracy and creates the wall with mm accuracy.

Location: Building - Point Cloud - Wall Detection - Wall detection on floor plan

1. Draw a cursor line along and near the center of the point cloud points representing the two sides of the wall.

2. Then use the expanding rectangle cursor to enclose the two sides of the wall.

3. Press Enter to create the new wall.

Repeat it in a loop.

Manual Refinement

Wall detection is part of a semi-automatic workflow.

After wall detection:

adjust wall positions,
correct dimensions,
fix wall connections using the L, T connection commands,
and validate BIM geometry.

Manual refinement is essential for professional BIM quality.For non-parallel walls:

The algorithm creates the two sidelines of wall in the point cloud with high accuracy.

Location: Building - Point Cloud - Wall Detection - Non-Parallel wall detection on floor plan

1. Specify a point near the start and end of the point cloud points representing the wall first sideline.

2. Specify a point near the start and end of the point cloud points representing the wall first sideline.

The non-parallel wall is generated on the current building level.

2. Repeat in a loop or press Enter to close the command.