Chinese, US researchers develop hydrographic printing for 3D objects

ECONOMICAL: Hydrographic printing is relatively cheap and can be applied to metal, plastic, wood, porcelain, rubber and others.

Chinese and US researchers have jointly developed a new technique that enables the transfer of colour inks on a thin film to the surface of manufactured 3D objects and colours the surface with the most precise alignment.

Researchers from China's Zhejiang University and Columbia University in the US call the method "computational hydrographic printing."

The hydrographic process involves placing a PVA film with printed colour patterns on top of a container of water, spraying it with an activator chemical, and then dipping the object onto the film. The film wraps the surface of the object.

Using the computational process, the object is held by a gripper at the end of a rod. A 3D vision system measures the location and orientation of the object with respect to the film. The computational model the researchers designed is used to predict colour film distortion during hydrographic immersion and generates a "texture map" to guide the object onto the film.

The system also relies on 3D surface reconstruction technique to construct a point cloud of the 3D object as well as obtaining the exact location of the film on the water.

"First, we print a surface colour pattern with an inkjet printer and then use it to create a film for hydrographic printing. During the process, the film wraps the surface of a 3D object. That's how it shows our 3D design concept," said Zhou Kun, lead researcher and director of the State Key Lab of CAD& CG at Zhejiang University.

To avoid severe film distortion and the risk of the film tearing, the researchers have introduced a multi-immersion design. The object can be dipped multiple times, each with a different orientation and a film printed with a different colour pattern.

Hydrographic printing is relatively inexpensive and can be applied to various materials including metal, plastic, wood, porcelain and rubber, said Zhou.

The research will be presented at the 42nd International Conference and Exhibition on Computer Graphics and Interactive Techniques (Siggraph 2015) in August in Los Angeles. — Reuters