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  1. #1
    3D Printer Noob
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    Mar 2018
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    Really challenging 3D scan processing for 3D printing

    That was one of the most interesting orders in terms of the variety of technologies for 3D scan processing: sculpting tools, reverse engineering, surface modeling from scratch.

    было - стало.png

    A customer sent me the 3D scan data and wanted to get a reduced copy of the monument for 3D printing: the real diameter of the base was about 6 meters and the printed copy was supposed to be about 30 centimeters.

    I assume that the point cloud was collected with a mobile landscape 3D scanner. It contained a huge number of errors and had a quite low resolution. I’d use a handheld scanner or a tracking system in this particular case, but I had to work with that point cloud.

    The plan was:

    1. triangulate the point cloud;
    2. to align the scan in the coordinate system;
    3. to scale the mesh to desired size;
    4. to split the scan into separate objects;
    5. to heal the objects and add missing geometry;
    6. to enhance detailing;
    7. to construct the benches and the floor;
    8. to join the objects and export as STL.


    Screenshot_1.jpg

    The monument had many inaccessible areas for scanning: legs and backs of the men were hidden in the shade of the benches. I restored these surfaces from scratch in Geomagic Studio 12. Sometimes there were so little data that I had to extend existing boundaries and transform them. The extremely useful 3D sculpting tools - ‘Sculpt Knife’ and ‘Deform Region’ - saved a lot of time. Smaller holes were filled with patches tangent to the mesh boundaries.

    Moreover, there were errors of scan alignment - two or even three layers in certain places. I had to define the necessary scan, delete the others and rebuild missing areas manually. There are different types of selectors in Geomagic which allow to capture and remove needless data (in the most cases I prefer ‘Lasso’).

    было - стало 2.png

    Before restoration of the details with the sculpting tools, it was necessary to increase the number of triangles. Faces, details of uniform, a dog’s fur - all of it demanded efforts and time to be reconstructed. Some elements were restored based on photos. The dog’s scan was isolated in a separate file to recreate its fur. I adjusted the suitable size of the sculpting knife for narrow linear deformations, which imitate the fur, and used the tool to add and remove material. Thus, the texture of the object was restored manually.

    было - стало 3.png

    The monument was made of bronze and had dark surface that caused problems for the optical scanner. That is why there were a lot of small holes and errors which were repaired automatically.

    The benches and the floor were reconstructed in a CAD software (CATIA) and saved as STL. Then I placed all the objects on the scene in initial positions with small overlaps and joined them into a single shell.

    реверс.png

    The order execution took 3 days. So if you are a skilled engineer or ‘sculptor’, you can handle almost every 3D scan. But if you want to make your life easier, use the equipment that suits your tasks.


    Here is the printed file:

    напечатанный.jpg



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  3. #2
    3D Printer Noob
    Join Date
    Aug 2018
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    Why did you use CATIA for data processing the benches and the floor? You could handle it using Geomagic, or I missed something?

 

 

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