Cutting-edge printing method breathes life into complex 3D-printed objects

Screenshot from YouTube user Changxi Zheng

Screenshot from YouTube user Changxi Zheng

A technique for physically decorating 3D surfaces with user-customized color textures has been generated by a team of researchers from China and the US. The new method is cost-effective and can be used on a range of materials, from plastic to porcelain.

A group of researchers from Zheijiang and Columbia Universities
have titled their trailblazing method ‘computational
hydrographic printing
’. According to Kun Zhou, a Cheung Kong professor in
the Computer Science Department of Zhejiang, the new method goes
with a very low operation cost (less than 40 US cents per

While hydrographic printing (the technique used for transferring
color inks on a thin film to the surface of a manufactured 3D
object) enables high-quality coloring of object surfaces, it’s
notorious for the inability to precisely register color texture
to complex patterns. According to the researchers, it’s
“uncontrollable” in the sense that the surface location
where the color ink is transferred to is totally unpredictable.
As a result, these limitations render it impossible to generate
certain 3D surface textures.

Computational hydrographic printing, in contrast, not only boasts
the versatility of traditional hydrographic printing, but also
enables point-by-point detailed alignment of surface textures to
complex 3D surfaces. The researchers have created what they hail
as “the first computational model for simulating hydrographic
printing process.”

As demonstrated on the
demo video, the key step of the hydrographic printing method is
the computation of a pixel image to print on a PVA (a
water-soluble synthetic polymer) film. After it’s transferred to
the object’s surface, the colors form a desired texture. The
researchers attach the object on a mechanical gripper and dip it
into the water.

The team uses a Microsoft Kinect that maps the location of the
object before immersion; the object orientation and dipping
location are both measured by the 3D vision system.

The primary objective of the simulation step, according to the
researchers, is to establish a map that plots points on the color
film to points on the object’s surface. Later, they use the
inverse of this map to determine the color patterns that need to
be printed on a color film.

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When dealing with complex surfaces, the team has extended their
method to enable multiple immersions, each with a different
object orientation, of course, in order the combined colors of
individual immersions could form a desired texture on the object

The researchers say their method has several limitations,
however. If an object is highly concave and has “significant
” it becomes difficult to cover its entire
surface with color films, even when using multiple immersions.
Another drawback of the technique is that the color film
distortion during the hydrographic printing affects the
appearance of the color. So the more stretched a film becomes,
the lighter the color appears when transferred to the surface.

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