(Adds material on VR, moves up reference to Allo, changes headline)

By Deborah M. Todd

MOUNTAIN VIEW, California, May 18 (Reuters) - Alphabet's Google Inc unveiled its answer to Amazon's Alexa virtual assistant along with new messaging and virtual reality products at its annual I/O developer conference on Wednesday, doubling down on artificial intelligence and machine learning as the keys to its future.

Google Chief Executive Sundar Pichai introduced Google Assistant, a virtual personal assistant, along with the tabletop speaker appliance Google Home.

He also unveiled Allo, a new messaging service that will compete with Facebook's WhatsApp and Messenger products and feature a chatbot powered by the Google Assistant. Allo, like WhatsApp, will also have end-to-end encryption when it is rolled out this summer.

Amazon's Echo, a surprise hit that has other tech giants racing to match it, uses a virtual assistant called Alexa, a cloud-based system that controls the Echo speaker and responds to voice-controlled commands by users.

Like Alexa, Google Assistant can search the internet and adjust your schedule. However, Pichai said Google Assistant can use images and other information to provide more intuitive results.

"You can be in front of this structure in Chicago and ask Google who designed this and it will understand in this context that the name of that designer is Anish Kapoor," said Pichai, pointing toward a photo of Chicago's Cloud Gate sculpture.

For Google Home, the Google Assistant merges with Chromecast and smart home devices to control televisions, thermostats and other products. Google did not offer a specific release date or pricing for Google Home, saying only that it will be available later this year.



VIRTUAL REALITY

Google's other big announcement at Wednesday's event, held at an outdoor amphitheatre near Google's headquarters, was a virtual reality platform called Daydream designed to work with the Android mobile operating system.

Daydream addresses latency and other issues affecting playback on smartphones, according to Clay Bavor, Google's vice president of virtual reality.

Bavor also announced a virtual reality headset powered by a smooth, two-button controller with orientation sensors that help determine positioning in virtual environments. Facebook is also making a big push in virtual reality with its Oculus headset, and Apple has indicated its interest in VR technology as well.

Bavor also said the division has "rebuilt YouTube from the ground up" to feature improved audio to support virtual reality screening.

Google offered no timetable on the VR headset, but said Daydream-ready phones would likely hit the market by autumn.

(Reporting by Deborah M. Todd in Mountain View and Narottam Medhora in Bengaluru; Editing by Alan Crosby and Marguerita Choy) ((narottam.medhora@thomsonreuters.com; Within U.S. 1-646-223-8780, Outside U.S. +91 8067496409 ; Reuters Messaging: narottam.medhora.thomsonreuters.com@reuters.net))