ON COMPUTERS

Human holograms impressive but still have a ways to go

Talk about lowering your carbon footprint. Companies are transporting holograms of top executives and celebrities around the world, making them show up together on a virtual stage.

The idea has been around for a while. In 2012, a hologram of the late rapper Tupac Shakur appeared onstage at the annual music and arts festival in Coachella, Calif. I looked at something similar at hologram developer arhtmedia.com, the website of hologram developer Augmented Reality Holographic Telepresence Media. British actor Colin Firth materialized out of nowhere to talk onstage. It looked like teleportation. Wow!

A techy friend is skeptical. "It's obvious that the images are flat and not 3-D," he said. I decided to ask around, and went to Quora.com, the question-and-answer site. A gravitational wave researcher from the University of Glasgow in Scotland told me that Augmented Reality and other developers use the word "hologram" loosely. A hologram uses light that either starts from behind an image and passes through it, or it starts in front of the image and never comes near it. Augmented Reality seems to be using the second kind, he said, creating a 2-D version of a person instead of 3-D. "They mostly give shots from the front where it looks perfect. Good luck to them; it's probably good enough to be useful. But there's one or two brief diagonal shots where it looks like a photo on glass." Prices range from $15,000 to $40,000.

KILLING SPAM CALLS

Beware of RoboKiller, a popular app for blocking telemarketers and spam calls. Some users say it blocks their friends and paves the way for spammers. What's worse, they can't get rid of it. If this happens to you, go to deactivatemyphone.com to have RoboKiller or similar apps removed. I've had pretty good results with the app Truecaller, but am glad I now use an Android phone with automatic call screening. Call screening is available on Google Pixel, Motorola and Nokia phones.

INTERNUT

Terrafugia.com is the website of a company that makes flying cars. The site has a YouTube video showing it take off and land. This doesn't look like one of the awkward car/planes you may have seen. This thing is smooth. Volkswagen also has a car that levitates just above the ground called the Hover Car. A YouTube video shows it in China.

APP HAPPY

LetsRoam.com offers an app to take users on scavenger hunts in 400 cities worldwide, including Little Rock. The jaunts are done on foot and usually last 90 minutes to two hours. In the Little Rock adventure, you'll trek across the city in search of storied buildings, impressive sculptures and lovely views of the Arkansas River. How did the nine students depicted on the north mall of the state Capitol become national heroes? Who's pigging out at Riverfront Park? The cost is $12 per player, or you can get an annual pass with unlimited scavenger hunts for $63.

LEARN COMPUTER GRAPHICS

How do you make the graphics in popular video games like Fortnite or Call of Duty? Or create animations like those in the movies "Toy Story" and "Frozen"?

Gabriel Gambetta, the author of a new book, "Computer Graphics from Scratch," from No Starch Press, says anyone who is familiar with high school math can do it. But it's not a quick study. There's enough information in his book for a university course. In fact, the book is based on the course Gambetta taught before he became a senior engineer at Google. Previously, he founded the game company Mystery Studio and helped get game company Improbable off the ground when it had just 30 employees; it now has more than 500. His website, gabrielgambetta.com, includes his email address if you want to get in touch with him.

Joy Schwabach can be reached by email at joy.schwabach@gmail.com.

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