Researchers at Zhejiang University and Columbia University have found a way to precisely affix complex coloring to objects, making them look somewhat photo-real. They presented a new computational hydrographic printing method that inherits the versatility of traditional hydrographic printing.
Hydrographic printing is a well-known technique in industry for transferring color inks on a thin film to the surface of a manufactured 3D object. It enables high-quality coloring of object surfaces and works with a wide range of materials, but suffers from the inability to accurately register color texture to complex surface geometries. Thus, it is hardly usable by ordinary users with customized shapes and textures.
Traditional hydrographic printing is mainly used for coloring 3D shapes with repeated color patterns, because it lacks a method to map a surface texture to a printable 2D image and precisely register the color texture on surface. But this new computational method solves these problems, so user-specified color textures can be hydrographically printed.
This simulation enables them to compute a color image to feed into the hydrographic system for precise texture registration.They then build a physical hydrographic system upon off-the-shelf hardware, integrating virtual simulation, object calibration andcontrolled immersion. To overcome the difficulty of handling complex surfaces, they further extend the method to enable multiple immersions, each with a different object orientation, so the combined colors of individual immersions form a desired texture on the object surface. They validate the accuracy of the computational model through physical experiments, and demonstrate the efficacy and robustness of the system using a variety of objects with complex surface textures.
This works for complex surface geometries and a wide range of materials including plastic, wood and porcelain. The whole system is easy to set up for personal uses, and enjoys a low operational cost (less than 40 US cents per printing).
The researchers say their method has several limitations, however. If an object is highly concave and has “significant self-occlusions,” 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.
