The software analyses individual pixels to create the 3d model

Entire building exterior 3D-mapped with tablet

Researchers from ETH Zurich have been able to create an entire 3D model of the university’s main building in just 10 minutes using a tablet equipped with a fish-eye lens.

The research forms part of the development process for Google's Project Tango which the search giant has been working on for the last three years.

The 3D model is compiled from multiple images that are taken on a tablet with an integrated fish eye lens camera. The system uses triangulation in a similar fashion to geodetic surveying, which is a method used to account for the curvature of the surface of the earth when conducting geographical surveys.

The software analyses two images of a building's façade that were taken from different positions. For each pixel in an image, it searches for the corresponding element in the other.

It is then able to determine how far each picture element is from the device and uses this information to generate a 3D model of the object.

Earlier 3D mapping systems lacked detail and were restricted to the outlines of buildings and basic features such as window openings and doorways. One method projects a grid of infra-red onto an object which is captured by a camera to generate a three-dimensional map of the object.

"This technique works well indoors," says Torsten Sattler, a member of the research team, but he says that it is poorly suited to outdoor shots because sunlight contains light on the infra-red spectrum that interferes with the results. "Outdoors, our method has clear advantages,” he says.

The new method allows for a level of detail unavailable with the infra-red system as it is capable of showing architectural nuances such as the arrangement of bricks in a stone façade.

"In future, this could probably even be used to survey entire districts," says Sattler.

Mapping large objects commonly causes calculation errors with regards to the 3D coordinates. "We solved the problem by programming the software to scrupulously delete all dubious values," he says.

Real-time feedback is also needed to ensure that the 3D model does not become a patchwork. A preview mode also lets the user know which building areas they have collected enough information for and which still require scanning.

The team believes the technology could be used to map archaeological excavations, allow cars to automatically detect the edge of roads and the size of parking spaces, and develop virtual-reality computer games featuring real buildings.

Lenovo and Google are currently collaborating on the first smartphone to use Project Tango which is due to be released this summer.

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