Setting measurement units for non-georeferenced point clouds
🕐 Read time: 3 min
Written By Clark Yuan
Last updated 10 days ago
Overview
The base unit defines how coordinate values in a point cloud are interpreted by Stitch3D. It answers one question: "What does 1 coordinate unit equal in the real world?"
This is separate from your display unit, which only controls how measurements are shown to you. The base unit affects actual calculation accuracy for distances, areas, and volumes.
Why this setting exists
When you upload a point cloud, Stitch3D automatically tries to detect its unit from file metadata — CRS, EPSG code, scale factors, and similar fields. For most georeferenced files, this works automatically.
Some files, however, cannot be detected reliably:
Files with no CRS
Files with incomplete or missing metadata
Files exported from CAD or Revit without unit information
Local scans without georeferencing
In these cases, Stitch3D cannot determine whether coordinates represent meters, feet, millimeters, or another unit. You must manually define the base unit to ensure measurement accuracy.
For files that Stitch3D cannot detect a base unit of measurement for, you will see three things:
A warning sign that says “No base unit detected” prompting you to set a base unit.
A Coordinate Reference System that says “No CRS detected for Layer prompting you to set a base unit.
In the Location Banner, unit displays “Unknown”
What the base unit affects
Setting the correct base unit directly affects the accuracy of:
Distance measurements
Area calculations
Volume calculations
Scale display in the Viewer
Example: If the base unit is set to Meters, a coordinate difference of 10 equals 10 meters. If the base unit is set to Feet, the same coordinate difference of 10 equals 10 feet. The raw coordinate values are identical; only the interpretation changes.
How to set the base unit
Open your Project and enter the Viewer.
Option 1 - Click the “Set base unit” in the warning sign under the Layers Panel
Option 2 - Click the “Set base unit” under the Coordinate Reference System label in the Information Panel
Option 3 - Hover over the greyed out toolbar and click Set base unit
Select either the Metric or Imperial base unit of measurement.
ℹ️ Note: The base unit can only be set manually on files where the unit was not automatically detected. If the unit was detected from metadata, the field is locked and cannot be changed.
Measurement tool behavior
Stitch3D enforces strict unit validation rules to protect measurement accuracy. Measurement tools behave differently depending on the unit status of your files.
If units are unknown
If one or more point clouds in your Project have an unknown base unit, all measurement tools are disabled. You must manually select a base unit for each unknown file before measurements become available.
If units do not match across files
If multiple files in a Project have different base units — for example, one file in meters and another in feet — measurement tools remain disabled.
To resolve this, you have two options:
Manually set the base unit on files where the unit was unknown, matching them to the other files in the Project. Only do this if you are certain the files were captured in the same unit.
Remove the files with mismatched units, or create a new Project and upload only files that share the same unit.
⚠️ Important: You can only manually change the base unit on files where the unit was not automatically detected. If a file's unit was detected from metadata and conflicts with other files, the only resolution is to remove it or start a new Project with consistent units.
If units are automatically detected
If Stitch3D successfully detects the base unit from file metadata, the unit is locked and cannot be changed manually. This prevents accidental scale corruption.
Why we enforce unit consistency
Mixing different units in one Project would result in incorrect distances, incorrect volumes, misaligned overlays, and invalid measurements. For survey, civil, BIM, and LiDAR workflows, unit consistency is critical.
Important
Manually changing the base unit:
Does not modify the original file
Does not reproject coordinates
Does not alter the CRS
Only changes how the Viewer interprets coordinate values for measurements
Related articles
Selecting a Viewer unit of measurement