Four Seasons in One Minute: Instant Virtual 3D Trees from Video

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Scientists have created a way to generate realistic 3D computer models of trees, using a short video clip of a real tree as source material.

The technique represents a huge leap forward for people who need to create natural-looking 3D environments, such as animators, videogame designers, and architects.

Until now, if you wanted a 3D virtual tree in your videogame, you had to either model it from a photo, draw it from scratch, or hand-code it using a computer technique called L-system. But these methods are expensive, difficult, and time-consuming.

Peter Hall, associate professor at the Computer Science department of the University of Bath, England, has been working on new software that makes the process cheap, easy, and quick.

The software he’s created (with PHD student Chuan Li) does amazing things with a short video clip of a tree swaying in the breeze.

From just a few minutes of video footage, it can extract the tree’s shape and structure and spit out a fully manipulatable 3D sibling, which can then be inserted into other digital creations like videogames and movies.

The magic doesn’t stop there, though. Hall’s software can also take the original video footage of a single tree and extrapolate variants from it. They will all look similar, but not exactly alike. An instant computer-generated forest.

The software works by taking rough estimates of the tree’s size and structure, building a statistical model of the “average” tree. Then it builds new trees by slightly varying the average figures for height, branch length, and branch angles. More realistic movement is made possible by another new idea; the virtual tree trunk is told to “shake” by a certain amount, and all the branches connected to it will shake too.

Hall’s virtual forest will do whatever he wants it to. The virtual wind created by shaking trunks can be a gentle breeze or a howling gale. The trees can be commanded to change seasons in an instant, and they look just as good with or without foliage. Everything happens differently on each tree, with variations of shape and color. The effect is startlingly realistic.

And all that’s needed to create this forest is a snippet of footage of a single tree in the parking lot. To make more varied models, just take video of different types of tree.

Hall and Li are now working on other natural phenomena, such as water and fire.

Unsurprisingly, Hall’s work has got videogame producers and movie makers beating a path to his door. Globally famous names from the movie, TV and games industries have already been in touch, hoping to make use of the technology.

So the next time you’re absorbed in some virtual forest environment, perhaps squatting behind cover with your sniper’s rifle ready to fire, pause for a moment and look at the trees around you. Listen to the breeze, and watch the foliage swaying. Your biggest challenge will be working out which parking lot the original tree was growing in.