Until this month, few CAD (computer-aided design) users had heard of AtLast's SketchUp 5.0 (www.sketchup.com) - see the June2006 edition of PC World Magazine, p22 for Damien Donnelly's First Look. Autodesk has long dominated the technical illustration field, particularly when it comes to architectural models. SketchUp, a quirky modelling application, hadn't had much of a look-in.

But after years in the shadows, SketchUp is suddenly the hottest CAD application on the market. The reason? It's been bought by Google.

The news came as a surprise to many - after all, where's the obvious connection between a search-engine company and a 3-D authoring application? But it was surely inevitable that SketchUp would be snapped up sooner or later, because anyone who has used it has raved about it. Those who have baulked at the complexity of other 3-D applications find SketchUp easy to use.

The program really couldn't be simpler. You start with a basic isometric view - that is to say, looking at objects from a slightly raised diagonal angle. You draw a plane or enter its dimensions in a dialogue box, then use a delightfully simple Push/Pull tool to extend this plane upwards or downwards, giving it depth.

While you can, at a stretch, use SketchUp to model organic elements such as animals and humans, it's really aimed at architects and planners. Realistic buildings are easy to draw thanks to a range of pre-built textures and colours with an opacity adjuster, so you can add transparency effects, such as glass, to your models.

Impressive features

But its simplicity shouldn't imply that this is an underpowered piece of software. Take one of SketchUp's best features, inference locking, where the program suggests possible construction lines and points parallel or perpendicular to those on other planes. Equally impressive is a sectioning tool that cuts out parts of a plane so you can create windows or doors, or split a plane to get a cross-section view of your model.

To be fair, it's not the answer to every CAD problem - Autodesk is the market leader for a reason. But SketchUp shines because it makes it easy to import and export designs from other CAD packages in industry-standard DWG or DXF formats. I know people who use both applications in tandem. Basic plans are drawn up in Autodesk, brought to life quickly in SketchUp and then exported back to Autodesk for final tweaking.

Friends of the Earth

But SketchUp has been a great little program for years. Why the fuss about it now - and, more importantly, what's the sudden attraction for Google? The answer lies with the recently released free planetary-mapping application Google Earth (http://earth.google.com).

Google Earth is a great program, but surprisingly few people realise that it is much more than an (admittedly amazing) way of exploring satellite views of the globe. You can also fly through buildings in three dimensions, with the structures rendered accurately on the map.

It's stunning to see this in action - just turn on the Buildings option and zoom through a large US city to see the effect. Nearly 40 cities Stateside have 3-D outlines of larger buildings.

Creating animations

It isn't quite in the same league as Toy Story, but don't sniff at SketchUp's neatly thought-out animation feature. It works on the principle that each SketchUp file can contain more than one page, each of which can have its own settings, such as camera or display. You can't tweak the detail of the animation, but SketchUp handles the smooth transitions between pages. The best part of the animation is that you can preview its effect in SketchUp and adjust the settings of each page independently in a Page Manager window (click here to view a screenshot). This means it's a great shortcut when it comes to getting multiple views of an object - simply store each camera view on a different page, and you can flick between them quickly.

The pages can be saved as an animation and exported as a plain AVI file. This provides a handy way of demonstrating your 3-D models in stunning multimedia detail to clients who don't have a SketchUp-compatible player.