Importowanie plików STL lub OBJ

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Topic
Tutorial
Importowanie plików STL lub OBJ
Level
Beginner
Time to complete
30 minutes
Authors
r-frank, tłumaczenie: tomaszkowalczyk94
FreeCAD version
0.16.6703
Example files

See also
None

Wprowadzenie

W tym tutorialu omówimy jak importować pliki STL/OBJ do FreeCAD-a. Ponieważ formaty STL/OBJ są opisane przez siatkę wielokątów i nie posiadają przypisanych konkretnych jednostek wielkości, FreeCAD przyjmuje że wszystkie wartości podane w pliku są podane w mm. Jeśli jest inaczej, trzeba zeskalować model w aplikacji w której został stworzony (przed jego wyeksportowaniem) lub zeskalować model w FreeCAD po jego zaimportowaniu i konwersji do bryły.

Przykładowy plik

Dla tego przykładu możesz użyć swojego pliku STL lub stworzyć plik demo w ten sposób:

Otwórz FreeCAD
Stwórz nowy dokument
Zmień warsztat na mesh workbench
Dodaj torus przez Meshes → File:Mesh RegularSolid.png Regular solid... wyberają opcje:
- Radius1: 10 mm
- Radius2: 2 mm
- Sampling: 50
kliknij Create and then on Close
Zapisz plik za pomocą File → Save

Aby zaimportować plik STL lub OBJ, stwórz nowy dokument DreeCAD i wybierz File → Import z górnego menu.

Cleaning and repairing the STL/OBJ-File for preparing import

Basically, FreeCAD would import any STL/OBJ-File. But our goal is to have a solid which can be measured and changed (adding pads/pockets ..). For a successful conversion from mesh to solid we need to make sure that the mesh is “water-tight” (has no holes) or doesn’t have any other errors.
FreeCAD’s aim is not to be a good mesh modeler, it is designed to be a solid modeler. FreeCAD has some capabilities for mesh operation in mesh workbench and OpenSCAD workbench (some operations need OpenSCAD to be installed and configured in the FreeCAD-preferences).
Some users like to use third-party software for cleaning and repairing meshes, for example

Netfabb Basic (Windows/Linux/Mac) - free for personal use (automatic mesh repair available)
Meshlab (Windows/Linux/Mac) - Open Source

In this tutorial we will use the mesh workbench within FreeCAD to clean/repair/verify the mesh of our sample file.

Automatic testing and repairing

Open FreeCAD and the sample FreeCAD file containing the mesh object
Switch to mesh workbench
Make sure that your mesh object is selected in the tree view
Choose Meshes → Analyze → Evaluate & Repair mesh... from the top menu
Make sure the pull down menu on the top right corner displays the name of your mesh object
With the last point in the list reading "All above tests together" click on Analyze
The texts beside the tick boxes will change to reflect results of the different tests
If errors had been detected the corresponding check-boxes will be ticked and you will be able to select Repair
Choose Close to close the menu

Harmonizing normals

Harmonizing normals of a mesh object can be done by

Selecting your mesh object in the tree view
Choose Meshes → Harmonize normals from the top menu.

Tip: By choosing the mesh object in the tree view, going to the view tab in the property view and changing "Lighting" from "Two Side" to "One Side" you can identify triangles with flipped normals. If the normals point into the mesh the triangle will be shown in black.

Closing holes

You can also manually close holes in your mesh object by

Selecting your mesh object in the tree view
Choose Meshes → Fill holes... from the top menu
Specify maximum number of edges to be filled (3 is default)
Since STL and OBJ are meshes consisting of triangles the default number of edges should be sufficient

Another method of manually closing holes in your mesh object would be

Selecting your mesh object in the tree view
Choose Meshes → Close hole from the top menu
Select one of the edges of the hole in the mesh object in the 3D view
Right-Click in 3D view and choose Leave hole-filling mode to exit the command

Conversion mesh to solid

Switch to part workbench
Make sure your mesh object is selected in the tree view, otherwise select it
Choose Part → Create shape from mesh ... from top menu
Specify tolerance for sewing shape (0,1 is default)
A new object will be created in the tree view (with blue shape icon, instead of green mesh icon)
Select the newly created object in the tree view
Choose Part → Refine shape from the top menu
A new object will be created in the tree view and the previous one will be made invisible
Select the newly created object in the tree view
Choose Part → Convert to solid from the top menu
A new object will be created in the tree view, bearing "(Solid)" in its name, to indicate it is a solid

Since the created solid has no history and no editable features (like a simple copy in FreeCAD) you could delete all previous objects from the tree view. This would keep your file size small ...

Links

Export to STL or OBJ