When Google bought SketchUp many users were puzzled: what did the internet giant want with a 3D modeller? Most people, however, didn't care, so long as Google gave it away for free.

To begin with, Google didn't actually give the program away for free. Professional users who wanted to work their SketchUp ideas into something more polished needed to buy SketchUp Pro ($495) to be able to export and access their models in 3D. The free SketchUp was virtually identical, but restricted its users to 2D bitmap output.

There was one exception: you could output your projects as 3D models, but only for viewing in situ within Google Earth. It's this capability that explains Google's interest. Google needed to provide a free and easy way for end users to provide it with free content for Google Earth, and it's this mission that's clearly SketchUp 7.1's focus.

The stand-out feature is the new built-in texturing of models. SketchUp already lets you map photos of actual buildings onto your models. The problem is that the mapping process can be complex, and you need to have the photos in the first place. Not any more.

Now simply select a surface, right-click and select Get Photo Texture. SketchUp's new Photo Textures palette opens, split into two panes: the bottom showing a Google Maps aerial view and the top showing the associated Street View. Enter an address or postcode and the panels update accordingly.

Once you've set up your Street Map view, hit Select Region and a crop box appears, complete with mask overlay if your surface is non-rectangular. Move the corner pins into position, select Grab and your new bitmap texture is automatically applied, with built-in perspective correction.

This is extraordinary power, integrating Google Maps, Street View, SketchUp and Google Earth, essentially turning Google's Street View imagery into a massive free image resource. However, it's important not to get carried away. Not everywhere is covered by Street View, the imagery is of variable quality and you only ever get the fronts of buildings.

Where Photo Texturing comes into its own is in quickly, and sketchily, texturing the surrounding neighbourhood of your main project. It would still be a waste of effort to recreate buildings such as this, however, if someone had already done it and made it available.

And this is where the Components panel's new Nearby Models command comes in. Select it and SketchUp 7.1 automatically searches for all downloadable models within striking distance of your geo-referenced scene.

The value of this capability depends entirely on what models are available, and for the moment you have to think Manhattan rather than Manchester.

To prime the pump, the new Upload Command makes it easy to share buildings and the objects - doors, windows and so on - that make them up, by letting you post individual elements to the 3D Warehouse without having to first break up your scene.
You might think that was enough, but Google hasn't stopped there.

SketchUp's rendering has also been overhauled and orbiting, zooming and drawing are now significantly faster when working with larger projects. Then there are the new KMZ and DAE import and export capabilities.

At first sight this might seem hardly worth registering - after all, neither format is a household name: KMZ is the standalone Google Earth format and DAE is the XML-based Collada format on which it's built.

In fact, it's very significant. In particular, for the first time, Google is letting users of the free SketchUp export their work to a 3D format for use in ongoing workflows.

Whether this is viable depends on support, but most modern modellers support DAE. Now users of any Collada-supporting application can take advantage of Google SketchUp 7.1, and its pool of 3D Warehouse components, to quickly produce true 3D models for free.

The biggest significance is clearly for users of SketchUp Pro. Google has expanded Pro's functionality with a host of improvements to LayOut 2, such as improved drawing, grid handling, snapping, list formatting and new dimensioning.

Before this, most professional users had to stick with the commercial Pro release if they wanted to re-use their SketchUp work elsewhere, but with SketchUp 7.1 that may no longer be the case.