The 3D PDF of the 3D Textured Mesh generated by Pix4Dmapper can be used to make measurements.
To measure distances of the 3D Textured Mesh in the 3D PDF:
1. Open the 3D PDF with Adobe Reader.
2. Right click on the 3D Textured Mesh, go to Tools and click 3D Measurement Tools.
3. Right click on the model and click Define Model Units.
4. Select the model unit(s) in the drop down menu and click OK.
5. Left click on the model to mark the first vertex of the measurement and left click again to close the object. The measurement appears above the line that was drawn.