Introduction

Use this guide when the project requires geospatial orientation, and your surveyor has provided marked control points on site. You'll need at least three well-distributed control points with known coordinates. By the end, you'll have a dataset that aligns to project coordinates with minimal rework.

Note: For detailed instructions on how to capture control points with NavVis MLX refer to Control Point Capturing

A woman uses a handheld device to scan a wall-mounted marker in a modern setting.

Why it matters

Surveyed control points anchor and constrain the dataset, which helps reduce drift during capture and processing.
Loop closures strengthen SLAM stability and help prevent local misalignment.

What to do

Use at least three surveyed control points. Use more whenever possible for better accuracy.
Distribute control points evenly across zones and levels. Do not concentrate them in one area.
Plan the control point network before you scan.
Capture control points throughout the scan (early, mid-route, and near loop closures). Do not capture them all at the end of a long session.
Build in frequent loop closures by crossing your path regularly, even when you use surveyed control points.
Avoid layouts where control points fall on a single line. Use a geometry that spans the area or volume.

On-Site Guidelines

Keep still before you capture a control point and only move away once you are sure the control point has been successfully captured.
Keep a good distance and viewing angle. Include nearby flat surfaces (for example, wall and floor junctions).
Press the Control Point Button below the UI to capture the control point.
Ensure the device is stable and the laser scanner has a clear field of view when capturing the control point.
Do not block the field of view with your body. Stand behind the NavVis MLX so the laser scanner has as much visibility to the surrounding as possible.
Avoid leaning over or covering the sensor with clothing, hair, or safety vests.

A woman in a safety vest uses a device to inspect the floor tiles.

FAQ

What is the purpose of using surveyed control points in a project?

Surveyed control points anchor and constrain the dataset, helping to reduce drift during capture and processing.

How many control points are needed for accurate results?

At least three well-distributed control points are needed, but using more is recommended for better accuracy.

Should control points be concentrated in one area?

No, control points should be evenly distributed across zones and levels to ensure accuracy.

When should control points be captured during the scanning process?

Control points should be captured throughout the scan, including early, mid-route, and near loop closures, rather than all at the end.

Is it important to maintain a stable position when capturing control points?

Yes, you should keep still before capturing a control point and only move away once you are sure it has been successfully captured.

What should be avoided when capturing control points?

Avoid blocking the field of view with your body and do not lean over or cover the sensor with clothing, hair, or safety vests.