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Editorial Type: Review     Date: 07-2013    Views: 5991   

Graphisoft's BIMx provides tools for creating navigable models for sharing with clients, collaborators and other project members outside of the CAD environment, using the free BIMx Viewer, says David Chadwick

Graphisoft BIMx, which comes complete with ArchiCAD 17, allows users to create view only portable ArchiCAD models which can then be viewed and navigated on your desktop or laptop computer, saved in BIMx format (.bimx) to make them compatible with BIMx applications for iPad and other mobile devices, or viewed outside of the ArchiCAD application by using the free BIMx Viewer. They can then be shared with other ArchiCAD users at

The purpose is to allow non-technical or non ArchiCAD users to view and interact with 3D models to a limited extent. It enables them to visualise the structure as clients or potential users, to see how it will look at different times of the year or day, to plan interior fittings, take measurements, comment on materials and so on - but not to make edits or changes to the model. You are, after all, creating a view only model here, and the above applies to similar applications from other developers.

Once you have saved a model in BIMx file format, you can't then go and edit the 3D model or the surface materials in it. You have to go back to the original model in ArchiCAD, edit that, and then create another BIMx file.

There is another small caveat. As there were substantial changes in the upgrade from ArchiCAD 16 to ArchiCAD 17 that effected the BIMx file format, projects created in BIMx format from the later version can't be read by BIMx in ArchiCAD16.

When you set out to create a walk-through from the model there are a couple of options available to you. You can create a project giving the viewer free access to the entire model, which they can then navigate at will, take measurements, interrogate features, or you can create fly-through paths using cameras as gallery items, and limiting navigation to the views and clips you have saved to the gallery. You can either stitch all camera shots into one movie or launch a separate movie for each camera/gallery item.

If you are the originator of the BIMx Model, or have a BIMx licence, you have access to a range of editing tools through the BIMx menus, and can play around with Global Illumination, layer visibility, add a few more cameras and save new fly-through paths - and you can share the BIMx model with others who also have the ability to create their own fly-through paths. You can also share it with other members of the BIMx community using Graphisoft's online model sharing service - after you have created your online Graphisoft account.

If you are using the free BIMx Viewer you can't modify the model, save the file in any form, record a new camera path, or add a view to a gallery. You can't initialise Global Illumination either, but you can, if the BIMx model has been initialised, use the Global Illumination render mode.

As you are intending to create as realistic a viewing experience as you can on a variety of devices, from workstations to handheld - even iPhones - the BIMx model has to be optimised to suit the viewer. If there are going to be communication limitations for your intended audience, or you find you are having memory problems trying to initialise Global Illumination during editing, then you can reduce file sizes by eliminating unnecessary model components - furniture, GDL objects like door handles, etc. A single chair, for instance, requires more memory than all the walls in a project.

BIMx supports a number of texture types in a variety of formats - jpg, bmp, tif, png etc. - plus alpha channel texture effects. For the latter to be detected inside BIMx, though, you have to enable transparency in the ArchiCAD material or texture properties; but the algorithms invoked to do this may have a significant impact on performance.

Shadows are a critical element of a scene and are rendered using the OpenGL ARB-shadow extension, which works by rendering the sunlit scene into a texture map, which is then projected onto the screen, where OpenGL determines whether a pixel is in shadow or not. Larger texture maps produce better shadows with the highest quality being determined by the memory size of your graphics card. If the model is too big, or the car to small, the model may lose some of your artifacts!

You can utilise the whole screen to run BIMx models, loading the menu only when you need to do some editing as a black band across the lower part of the screen. Besides Open and Save - and a single Share BIMx Model command - the first function you will want to access is the Settings dialogue, which stores all the parameters related to BIMx model display and navigation control.

As realism is all about how well a model is rendered Graphisoft provides a number of options, and it is worth looking at each in some depth to appreciate the quality of different types of realism (you have to think about that statement) that can be achieved.

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