Google is acquiring Panoramio, a photo-sharing Web site based in Spain that lets people upload photos and identify where they were taken by placing them on Google Earth or Google Maps, where they can be viewed by the public.

The companies have already been working together since the start of the year, when Google made Panoramio the default photo layer for Google Earth. Panoramio has seen its usage surge since then, recently passing 1 million "geo-located" photos.

In a blog posting Wednesday, Google said it was buying the company to integrate its services more closely with its own -- although it isn't saying exactly how yet -- and to boost its own technical resources. It should also help to strengthen Panoramio's infrastructure, leading to more reliable service for end users.

Financial terms of the acquisition, which is pending, were not disclosed. Google said it planned to keep operating the site for now and that there won't be any immediate changes for Panoramio's users.

The move should help to strengthen Google's position against Yahoo for providing online photo services. Yahoo owns the popular Flickr photo-sharing service, whose users can also locate their photos on Google Earth, although they don't appear as the default layer.

Panoramio said it was "very (and we mean very) happy" to be acquired by Google. "To watch our little project grow since its conception one and a half years ago has been an amazing experience," cofounder Eduardo Manchón wrote in a blog posting.

Panoramio was launched in October 2005. About 300,000 people had signed up for the service as of March this year, and in February the site had 4 million unique visitors and 30 million page views, according to Panoramio.

The company released an API (application programming interface) recently that lets other Web sites include Panoramio functionality in their site.

It gave its users the option to remove all their photos and personal data before they are transferred to Google.