photogrammetry to CAD
Forum rules
and Helpful information
and Helpful information
IMPORTANT: Please click here and read this first, before asking for help
Also, be nice to others! Read the FreeCAD code of conduct!
Also, be nice to others! Read the FreeCAD code of conduct!
Re: photogrammetry to CAD
Photogrammetry is better for establishing proportion than absolute measurement if the camera isn't fixed, so it helps to place reference objects that you can derive edges and sizes from in the scenes that you're recording. That's especially true for organic objects like the tree stump that you show. A cardboard box in that view would give a size reference, and its perspective in the scene gives the focal distance of the camera lens. Some commercial CAD apps have tools to find "analytic" surfaces for man-made/non-organic objects, these are planes and conical/cylindrical/ellipsoidal surfaces. They usually require the user to identify the mesh facets that compose the analytic surface, and the program refines the parameters of the analytic surface to best fit the facets/points, where the surface is parametrised to be within as close an average proximity to the scan's points/vertices as can be found.
Re: photogrammetry to CAD
With CloudCompare. Use Scale/Multiplythschrader wrote: ↑Sat Nov 21, 2020 5:17 pm How to scale a point object?
Treestump has ca. 60 cm diameter in reality, cube size 2 mm!
...
Regards
Re: photogrammetry to CAD
It could be a unit issue: 60cm = ca. 2ft.