FreeCAD and photogrammetry

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l3VGV
Posts: 36
Joined: Sat Oct 12, 2019 11:04 am

FreeCAD and photogrammetry

Postby l3VGV » Sat Oct 12, 2019 11:21 am

Hello.

Im learning FreeCAD v 0.18

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16131 (Git)
Build type: Release
Branch: releases/FreeCAD-0-18
Hash: 3129ae4296e40ed20e7b3d460b86e6969acbe1c3
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: Russian/Russia (ru_RU)


im able to crate models of square, round and other simple pars, but what im up to is a complex part of joystick, wich is totaly made from curves. So i decided to make some kind of 3d model, without a proper scaner i used a camera and photogrammetry software, that was a partial success.

Now i imported that as mesh and used section to make drafts, then i use b-splines. All of that take a lot of time. So, am i doing it right? Or maybe ther is some other way to solve that.


pictures of part im trying to model, painted becose photogrammetry do not work on black surfaces.
Image

Mesh
Image
Image
Image
User avatar
GlouGlou
Posts: 2749
Joined: Sun Apr 05, 2015 9:02 am
Location: La Rochelle, France

Re: FreeCAD and photogrammetry

Postby GlouGlou » Sat Oct 12, 2019 1:24 pm

You could use CurvesWB to describe your model.
And share you STL file as well.
l3VGV
Posts: 36
Joined: Sat Oct 12, 2019 11:04 am

Re: FreeCAD and photogrammetry

Postby l3VGV » Sat Oct 12, 2019 1:57 pm

Here is STL, forum do not alow me to attach a large file, so external link, sory.

https://drive.google.com/file/d/1g1HmDQ ... sp=sharing
l3VGV
Posts: 36
Joined: Sat Oct 12, 2019 11:04 am

Re: FreeCAD and photogrammetry

Postby l3VGV » Mon Feb 17, 2020 12:55 pm

To share my finding and experience.

1) i was able to do what i wanted. From 3d scanned data i made freecad part and 3d printed it
2) it toke alot of trials and errors to achieve

I wasnt able to find any free to use software for automated mesh to surface reconstruction, to produce solid object. Converting 20-30k faces into a solid is possible, but not pleasant to work with.



Advice from mr GlouGlou, i used it, thank you, again!
Work reasonable well. First i get my mesh into freecad, then use DraftWB spline to make a closed loop, then i use SurfaceWB surface, one that made from closed loop and points and aditinal curves. So if u carful, u can add points and another draft splines ther, and it will not warp on you. Nice and easy, but take alot of time, and every once in a while dreaftWB decide to play some joke on you and all new pointw you drop hoping that they will snap to mesh, well they will float a few mm above it. Why? no idea.

Mesh
Image


Line is a boundary curve, draftWB closed. And alot uf not closed splines, as a "unbound edges", vertexes isnt shown, but the idea is the same.
One should not add to much, otherwise surface will go crazy. Oscillation is a term here?
Image

Oscillation
Image


Extruded surface
Image

But with all that done, i was able to extrude, export to stl and 3dprint without any issues. Curvy test was a success, part fit very well with almost no space betwen original surface and printed one.


Moral of the story: draft WB is great. Surfaces is cool too.
Attachments
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triplus
Posts: 9475
Joined: Mon Dec 12, 2011 4:45 pm

Re: FreeCAD and photogrammetry

Postby triplus » Mon Feb 17, 2020 10:10 pm

Thanks for the update and it's always nice to see FreeCAD surface capabilities progressing further. Such use cases and presentations, on what people do with FreeCAD. That can be motivating to developers working in this area.