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LA tree counting goes high tech

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File photo of palm trees in Southern California.
David McNew/Getty Images
File photo of palm trees in Southern California.

Los Angeles may be a huge city, teeming with people and buildings and cars. But we are also home to lots of trees — thousands of them.

Los Angeles may be a huge city, teeming with people and buildings and cars. But it is also home to thousands of trees. 

Just how many?  It's tough to say, but answers are on the way, thanks to modern technology.

That's where Caltech professor, Pietro Perona comes in.  Using a computer model first utilized in Pasadena, Pietro now plans to count trees in L.A. He says teaching a computer to identify a tree is all about pixels, and lots of different tree images.

"For example, suppose that you are trying to decide if a traffic light is red or green. You count how many pixels are green or red, and you can compare the two numbers and you can tell if it's more green or more red," he said. "By imitating processes that occur in the brain, like how neurons engage to discriminate details in a picture, computers are then able to differentiate between not just what is a green tree, but also what kind of tree it is. Having examples of different tree species are key for a computer's ability to distinguish between an oak and a Mexican fan palm," Perona said.   

Andy Lipkis, founder and president of Tree People, an environmental nonprofit based in Los Angeles, says knowing how many and what types of trees are in L.A. is key to humans.

"Many [trees] are being attacked and are dying right now, at a time when we need trees more than ever to shade and protect us from a city that's getting hotter and hotter, and threatening lives," he said.

Humans can also get involved, Lipkis said, with the Tree Map LA app. It allows people to give the exact location of a tree, and document details about it.

Press the blue play button above to hear the interview

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