It’s time to “3D sketch” your ideas with air scaffolding

By using a new 3D sketching workflow that combines hand motion and pen drawing, you can move your hands in the air to quickly express approximate volumes and then draw detailed shapes on top of them using a pen and a tablet, making it easier and faster to express your ideas in 3D space.

Article  |  Fall 2018

Everyone has probably dreamed of sketches popping off of a piece of paper and becoming real. This is a joyful dream for most people, but it is a dire necessity for field designers. All 3D shape designs for home appliances and automobiles, as well as film and game making begin at the designer’s pen tip. For a designer’s drawing to become a product in reality, one has to transform a designer’s 2D drawing into a 3D shape. However, this task requires a great deal of time and money and causes serious bottlenecks and friction in product development.

Why is it difficult to convert a 2D drawing into a 3D shape? Loss of depth information occurs when a 3D shape is expressed as a 2D drawing using perspective drawing techniques or as a photograph taken with a camera. On the other hand, when one creates a 3D shape from a planar 2D drawing or photograph with insufficient depth information, additional information that does not exist is needed. Furthermore, unlike photographs, it is more difficult to infer accurate 3D shapes that match the original intention from an inaccurate 2D drawing made by hand.

“3D sketching” is a technique that has been actively studied to fill in the “missing link” between these 2D drawings and 3D shapes. The main purpose of 3D sketching is to help designers naturally provide missing 3D shape information in the 2D drawing from the drawing process. For example, if a designer draws two symmetric curves from a single point of view or draws the same curves from different points of view, the geometric clues that are left in this process are collected and mathematically interpreted to define the proper 3D curve. As a result, designers can use 3D sketching to “draw directly” a 3D shape as if using a pen and paper, without using complex 3D CAD modeling software.

Professor Seok-Hyung Bae’s team at the Department of Industrial Design has further developed the technology called “air scaffolding”, in which designers quickly express 3D shapes by using their sense of space and natural hand motion and use them as “3D rough sketches” (Figures 1 & 2). For example, let us imagine a designer making an inline skate. When the designer moves his or her hands in the “air” as if touching and stroking an imaginary skate to express its approximate size and proportion, the “scaffolding” in the form of curve networks is extracted in real time from the hand joints’ 3D motion paths measured by the infrared hand tracking sensor. The designer can freely set any plane through the 3D rough sketches created and draw section curves on it to complete the inline skate’s 3D shape design with the guaranteed size and proportions (see video below).

 

 

This study, titled “Agile 3D sketching with air scaffolding”, won the Best Paper Award at ACM CHI 2018, one of the most prestigious and the biggest academic conference in the field of human-computer interaction (HCI), which was held in Montréal, QC, Canada from April 21 to 26. It was ranked among the top 1% (25) of all submissions (over 2,500) to the conference (Figure 3). In addition to enhancing the applicability of 3D sketching to design practice, this new technology of Professor Bae’s team is expected to usher in an era where all of us can easily express and share ideas in 3D, and it will further contribute to more rapid and flexible manufacturing innovation by linking itself to smart production technology such as 3D printing.

 

For more information, visit the project website below.
http://sketch.kaist.ac.kr/publications/2018_chi_agile_3d_sketching