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Scale constraints - PIX4Dmatic

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.

Important: There are two primary concepts for incorporating scale constraints.
  • A Scale constraint is a line defined by two Tie points.
  • A Scale constraint has a length.

Scale constraints in the 3D viewer

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


Deleting a Scale constraint

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


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.


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 scale_constraint.svg 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...