Introduction

Use this guide when scanning a building facade for the first time with NavVis MLX, especially with tricky elements like glass, long plain walls, or recessed entrances. You'll need the building plan, and a clear, feature-rich start point. By the end, you'll have complete facade coverage ready for alignment with interior scans.

Before You Go on Site

1. Analyze the building plan

Identify all facades you must capture.
Note corners, doors, canopies, overhangs, deep doorways or recesses, and large glass areas.
Mark areas that may need extra passes, such as long, uniform walls or recessed entrances.

2. Choose a clear start point

Select a spot that is easy to find again, such as a main entrance.
Prefer locations with features like frames, columns, ceilings, signs.
These details help:
- Align neighboring scans.
- Verify alignment quality in the overlap areas.

Best Practices for Scanning Facades

1. Walk the perimeter of the building

Keep the facade in view the whole time.
Avoid walking too close and perfectly parallel to facade. Stay at a slight angle so window frames stay visible.

A woman uses a device while walking along a pathway near a building.

Make sure you pass corners, columns, signs, and downspouts. These features help the SLAM algorithm keep track of your movement.

2. Add a few return passes

On long, straight sides of the building:

Walk along the facade at a distance that achieves the point cloud density required for your project.
Then walk back along the same side, slightly shifted from your initial path, so that you cross your previous path regularly.

You do not need additional panoramic images here; they are already captured during your walk.

A diagram illustrating a complex pathway with directional arrows indicating movement.

By walking forward and then backward with a slight offset, you
- Improve the coverage of the final point cloud.
- Provide more information for the SLAM algorithm to reconstruct a more accurate point cloud.

3. Pay attention to depth changes

For areas such as recesses, bays, arcades, or big canopies:

Slow down and keep the device steady.
Make more than one pass around these features to improve coverage of all surfaces.
Add a slow turn so NavVis MLX sees all parts of the facade, including ceilings, beams, and underside details.

A person holding a device near a building entrance, preparing for data collection.

4. Finish with overlap at your starting point

Return to your starting location, but ensure there is some overlap rather than just touching the start point.
If scanning inside as well, re-enter and end the scan near where you began. This loop closure is important for alignment.

View this short video on scanning a facades:

FAQ

What is the purpose of this guide?

This guide is designed to assist users in scanning a building facade for the first time with NavVis MLX, particularly when dealing with challenging elements.

What should I analyze before going on site?

You should analyze the building plan to identify all facades to capture, noting features like corners, doors, and large glass areas.

How do I choose a clear start point for scanning?

Select a spot that is easy to find again, such as a main entrance, preferably with features that help align neighboring scans.

Is it necessary to walk the perimeter of the building?

Yes, walking the perimeter while keeping the facade in view is crucial for effective scanning.

Should I make return passes on long, straight sides of the building?

Yes, adding return passes helps improve the coverage of the final point cloud.

What should I do in areas with depth changes?

In such areas, slow down, keep the device steady, and make multiple passes to improve coverage.

Is it important to finish with overlap at the starting point?

Yes, ensuring overlap at the starting point is important for alignment, especially if scanning inside as well.

Can I view a video on scanning facades?

Yes, there is a short video available that demonstrates how to scan facades.