PIX4Dmatic employs Scale constraints as a means to introduce known measurements or references into the photogrammetric process, enabling the reconstruction of accurate and correctly scaled 3D models.

Scale constraints in the 3D viewer

Scale constraints are symbolized in the 3D viewer as a magenta line.

Scale constraint in the 3D viewer.

Deleting a Scale constraint

The Scale constraint can be deleted by right-clicking on the constraint while in the 3D viewer.

Editing dialogue.

Properties panel

The Properties panel displays the length of the Scale constraint along with the accuracy of the line. When a new Scale constraint is created, the correct length must be entered in the Properties panel.

Properties panel.

How to scale a project

A Scale constraint is defined by two MTPs.  

1. Create an MTP. For more information: Tie Points (GCPs, MTPs, and CPs) - PIX4Dmatic.
2. Select the Scale constraint  icon or use the keyboard shortcut T.
3. Begin by left-clicking on a Tie point and finish the constraint by left-clicking on another Tie point. 
    

   Important: MTPs must be marked in the images for the Scale constraint to work.
4. Enter the length of the constraint in the Properties panel.
5. After drawing the Scale constraint, either Reoptimize or run Calibration (if not previously calibrated).
6. Click Save…