ASM
Virtual Earth Streets: Next-Generation 3D Modelling?
It will be at least another year before Microsoft is able to generate steet level views on its Virtual Earth website to match Google's Street View. However, the wait will be worth it.
That seemed to be one take home message from a presentation to a plenary session of the Map Asia conference by Alexander Weichart, the new managing director of Microsoft's Vexcel subsidiary in Graz, Germany.
Vexcel has delivered 10 roof-mounted cameras for Microsoft vehicles that are now driving around US cities. They should have completed their mission to photograph, at the very least, the inner city streets of all major US cities by the middle of 2009.
Meanwhile, Vexcel has been flying all those same cities to create 3D models. In and of itself this is not special – there are any number of aerial surveyors generating imagery of the world's big cities. The point about the Vexcel product is that it is designed for automatic photogrammetry.
The imagery is all being generated with Vexcel's own Ultracam cameras. The imagery is overlapped by about 90 per cent along the track of the aircraft flight, and about 60 per cent across the track. The implication is that each point under the aircraft is imaged about 15 times from different directions.
This massive redundancy might seem wasteful to a human photogrammetrist, but it is nirvana for a computer. In fact, with this type of input, it turns out that is is possible for a computer to generate a 3D model without human intervention. What's more, it can do some simple feature extraction of roads, buildings and cars.
A whole new generation of totally automated 3D models will result. The first one, of the city of Philadelphia, has just been completed.
This makes it possible to generate 3D city models fast. It also makes them cheap, and thus an essential part of Microsoft's plans to image 3000 cities around the world – regularly.
The problem with these models is that the sides of buildings – the facades – are poorly covered. The camera sees them only at a very oblique angle.
To make the models more realistic, Microsoft has begun using imagery from oblique cameras supplied by Pictometry. This goes some way towards fixing the problem.
The real solution is imagery taken from the street level. On the Vexcel plan, this will be draped over the existing 3D city model to give extremely high resolution views of the sides of buildings.
From the user's point of view, this will make Microsoft's product preferable to Google's. Google Street View is a click and wait representation of the streetscape. You click a point and get the imagery. To move, you click another point.
In Virtual Earth, you will actually be able to navigate around the model and view it from any angle and any position. Moreover, with all buildings recognised as separate entities, the potential is extraordinary. In such a model there is nothing to stop existing GIS attributes being assigned to objects.
However, there are a number of issues to resolve. Weichart did not disclose any plans to deliver the technology outside the US and there might be all sorts of security and legal reasons why this might be difficult in some countries.
