This project is a fine example of Reverse Engineering: capture an already existing physical 3D geometry and convert that into a 3D CAD model. This is of course the exact reverse of 'normal' engineering (which goes from CAD model to physical product), hence the name Reverse Engineering.
Subject is one of the most famous statues in the world: the Goddess of Love, created in marble by an anonymous Greek sculptor. It can be found in the
Louvre Museum in Paris. In this project only the lady's head has been reproduced.
To capture the existing geometry a 3D scanner is needed, and for this project the easy to use
Vivid scanner from Minolta has been used.
Any 3D scanner produces point cloud information (XYZ coordinates for many scanned points in space), and the Minolta software is able to convert this point cloud to polygon data (triangles) and export that as DXF. It can also combine scans from several sides to one 3D CAD model.
The resulting DXF file of the head contained 68000 points and 136000 facets; filesize 18 Mb. We were allowed to use it as courtesy of
Minolta USA: thanks !
This geometry is used in Lesson 3 of the
DeskProto Tutorial, to teach you about Rotation axis machining. As you will need the geometry to replay this lesson, the Venus STL-file has been made available as a
free download !
Below two pictures are shown from a later project: these two children have been scanned using a Minolta scanner, and next machined in wood.
Scanning was more difficult now, as children are less apt (less than a marble statue) to sit perfectly still during the scan. For milling in wood (here mahogany) it is advised to use special cutters for wood. Standard cutters may become very hot, making the wood black by burning it.
