The packet of ArchiCAD based on the idea of “virtual building”, was produced by Graphisoft company in 1984 year. Making perfect the tools and its application rules year by year, version by version, the packet was becoming more and more convenient and strong, but the basic idea was unchanged. According as the virtual building, the architect is represented the whole collection oriented on specialized tools of architectural projection. With its help the virtual building is created - capacitance building based on computer memory corresponding to real building.

One can get various information from this model:

• Drafts (storey plans, sections and fronts, nodes, details and so on)
• Result of quality index calculation (lists, specifications, comments and so on)
• Presentation materials (photorealistic representations, animated films, virtual reality scenes)
• Different format files for exchanging data with clients, consultants and other participants of projection process, which are used by other programs (AutoCAD, Microstation, 3D studio Max and etc.).

“Virtual building” gives an ability to work on drafts separating from each other, while working on a real building model, where all elements depend on each other, all changes done in project is automatically represented in documentation.

 Such dependence gives us ability to find out and estrange many problems, which could turn out on the next step of projection by all means. Besides, the idea of “virtual building” guarantees that each draft as precisely corresponds to each other as the representation of the same model’s various possibilities.

Parametric Constructions

The main particularity of the packet is that it gives possibility to work with the tool collection creating drafts of common building constructions: walls, windows, roofs and so on. All building constructions are represented parametrically (are described by characteristic parameters), consequently any part can be redacted by changing its parameters (pic.1).

That is why any constructive element has its own information for representing it on a draft as well as counting out its own properties. For ex.: Wall in ArchiCAD is not only a parallel line but is a whole parametric object having its characteristic qualities (for ex.: this possibility of the wall relating with another walls gives possibility to locate windows and doors) and includes necessary data (geometric sizes, line types, outside materials, in and polygonal surfaces and so on).

Objective technology

A broad library of various objects is installed together with ArchiCAD, which is used in the process of projection. There are more than 1000 objects in standard library- windows and doors, building constructions, furniture and illumination, elements of draft designs and visualization. It is possible to create elements separately. One can download the majority of objects via internet (free of course). Main peculiarity of ArchiCAD library is not expressed in library multiform but in application technology. In main objective technology of ArchiCAD there is a language of geometrical definition (GDL), giving us possibility to create parametric objects, which properties can define as user as various surface positions. (scope of draft, complications of

placing object, object position in space and etc.). For ex. Changing object scale, the detail quality of the object will be changed automatically. 2D symbols of the same stairs are able to look different on different stores.

Objects described with GDL language include 2D symbols of storey plans for creating 3D model capacitance expressions and all data for forming specification. Changing the basic parameters of an object it is possible to get infinitely different versions, different in shape, size, materials and other properties. (pic.3)

ArchiCAD - Basic complex projection

Functional possibilities of ArchiCAD packet are enough for accomplishing the main job of architectural projection. Although via the advantage of “virtual building” idea, putting outside modules and with the help of different programs, ArchiCAd may become the main projection program. ArchiCAD has the possibility of collective work by which the constructors group can combine their efforts and get the common decision.