A unique printing technology that produces photos that react to different angles of light the same way a three-dimensional object does has been developed by researchers at the University of California, Santa Cruz, Hewlett-Packard Laboratories, and 3M.
The technique, which uses special reflectance paper covered with thousands of tiny dimples, was presented in a paper in ACM Transactions on Graphics and a talk on August 6 at SIGGRAPH 2012.
James Davis, associate professor of computer science at UC Santa Cruz, elucidated that regular printed photos look the same despite the angle of the light because flat paper can’t reflect light the way three-dimensional objects do.
“If the paper is flat, it will always look flat no matter what you print on it. So the question became how to get the surface of the paper to have geometry to it. With the reflectance paper, for each pixel we have a little dimple that has all angular directions on its surface. Now we can print ink over it in a way that controls the angles of light that will be reflected from each pixel,”
Printing Reflectance Functions
The mathematical “reflectance function” expresses how light is reflected from each point on an object. Measuring the reflectance functions for an object or scene can be done by taking photographs lit from many different lighting directions.
Art historians and restorers use these techniques for documenting important works of art and historical artifacts, said Davis, a computer graphics expert who has developed software for displaying the results on a monitor.
“Right now the quality of our prints is nowhere near what museums would need, but the basic idea of being able to capture all of that information in a print is absolutely of interest to them. It’s not just a novelty. There are potential uses where people would want to take a picture and examine it later from different lighting angles,”
The idea for the project came out of a graduate course Davis was teaching, although he said it wouldn’t have gone anywhere if he hadn’t brought the idea to the HP researchers he was collaborating with on another project.
“This is a great example of industry-university collaboration. We had the idea, but we didn’t know how to make it work,”
The researchers at HP Laboratories, Tom Malzbender, and Ramin Samadani, finally teamed up with Douglas Dunn at 3M to develop the reflectance paper. At UCSC, Davis worked with two computer science graduate students, Steven Scher and Adam Crume, to write the software code for printing the reflectance functions.
You can read more about the project at the project website: graphics.soe.ucsc.edu/prf.
Reference: Malzbender, T., Samadani, R., Scher, S., Crume, A., Dunn, D., and Davis, J. 2012. Printing reflectance functions. ACM Trans. Graph. 31, 3, Article 20 (May 2012), 11 pages. DOI = 10.1145/2167076.2167078