At present, items obtained through 3D printing technology are mostly monochromatic, although there are many colors such as red, white and blue, and if you are lucky you might be able to get a two-color one. While the finished product itself may be able to show the details, the look is still rather dull.
Now, researchers have found a new way to accurately color the finished prints, which could make them look as real as a photograph.
The method, developed by two teams of researchers at Zhejiang University and Columbia University, is called computational hydrographic printing technology. Hydrographic printing is not new, and many manufacturers are using the technique to add repetitive patterns to inexpensive finished products to reduce production costs. The method involves the use of a sink and printed film.
The object to be colored is immersed in the water and the film is pressed against it, which automatically stretches out to completely encase the object. When the object is removed, the pattern looks as if it is part of the 3D printing process.
According to the researchers, it's nearly impossible to fit the object precisely to the film, so they tend to use repetitive patterns so that no one will notice even if something doesn't line up.
The researchers realized that if they could obtain a 3D scan of the original object and pre-immersed it in a sink with the printed film, they could figure out how to fit complex patterns on the object. However, the simulation would not have been possible if the modified hydrologic printing tool had not been used from the start. The hydrographic printing tool consists of a vertical, mechanized aluminum motorized arm and fixtures that move up and down at 5 millimeters per second, as well as a Microsoft Kinect 3D imaging device.
The Kinect's role is critical. Once the researchers have clamped an object into the fixture, it measures the precise position and orientation of the object in order to determine where the 3D film will be laid. It's not until the information has been gathered that the researchers can print the film on a standard inkjet printer, which incorporates the necessary image warping and stretching to make the final print look just right.
In a video announcing the inventive technology, the team of researchers from Zhejiang University and Columbia University showed a printed piece of a tiger mask, a zebra and a cat, among other finished products. Regarding the cat, the research team demonstrated a triple-dipping method that wrapped the original monochromatic kitten in highly realistic skin. The end result can look messy, but it's not perfect.
There are some limitations, of course. The researchers say they can't easily color in areas with large concave surfaces or areas that can't be scanned. Color mixing and accuracy were also a challenge, with some colors becoming slightly lighter than the original when the film was stretched. Despite one limitation or another, this method has a lot of promise because it can fit complex patterns and realistic photographs onto monochromatic objects obtained by 3D printing. Imagine scanning and printing a 3D model of a person's head, and then printing high-resolution photos of the face and sides, as well as the top and back. Multiple computer-navigated immersion prints could produce something truly chilling.