bim_curriculum12_lecture_09_parametric object technology.pdf

BIM Curriculum Lecture Notes 1

BIM Curriculum Lecture Notes

2 BIM Curriculum Lecture Notes

GraphisoftVisit the Graphisoft website at http://www.graphisoft.com for local distributor and product availability information.BIM Curriculum Lecture NotesCopyright © 2009 by Graphisoft, all rights reserved. Reproduction, paraphrasing or translation without express prior written permission is strictly prohibited.TrademarksArchiCAD®, Virtual Building™ and Virtual Building Solutions™ are trademarks of Graphisoft.All other trademarks are the property of their respective holders.

http://www.graphisoft.com

http://www.graphisoft.com

BIM Lecture 9: Parametric Object Technology

BIM LECTURE 9: PARAMETRIC OBJECT TECHNOLOGY

Topics• Object Technologies• Techniques• SolutionsArchitects want flexible and powerful software tools that support the modeling of even the most complicated building structures. Some building components follow strict regulations (e.g. concrete columns) thus they can be implemented relatively easily in CAD programs. Others can be found in many variations around the globe (e.g. windows or furniture objects), so they can’t be described with simple mathematical formulas. Parametric object technology offers the optimal way for modeling these complex elements. This lecture introduces the advantages of the parametric approach through Graphisoft’s GDL technology.

OBJECT TECHNOLOGIES IN CADUsers want to be able to create custom objects that they can easily insert in the BIM model. A rich library of objects is also a MUST in contemporary BIM programs. CAD developers support different object strategies in their applications. One group of programs works with non-parametric objects; others are committed to the parametric approach. The major difference is that a single non-parametric object can describe only one product, while a parametric object may include many elements.We can also distinguish the object technologies by the location of the objects. Most CAD programs allow the storing of objects in internal or external files. When an external object is placed in a project, the program will either save the object with the project, or save only the link to the external file. Both solutions have advantages and disadvantages:• Internal objects increase the project file size. On the other hand they will never be missing from the projects.• The use of external objects reduces file size. However, the objects might be missing from the project if the object files

are renamed or moved.

BENEFITS OF THE PARAMETRIC APPROACH

The parametric object solution offers significant advantages over non-parametric object technologies:• Compact object format resulting smaller project file size• Intelligent building elements automatically following the changes of the project environment (e.g. Scale)• Design variations can be compared easily• Easy to maintain object libraries• Efficient way for manufacturers to publish their productsLet’s talk a little bit more about managing change. Architects get paid for great architecture but a significant percentage of their time is spent on managing change – something the customer does NOT pay for! The easier it is to manage change, the more profitable a firm can be.The pictures show the parametric window object changing its 2D representation automatically according to the current project scale.



The next example is a parametric roof detail that is able to follow the changes of the roof angle or the insulation thickness.

WHAT IS GDL?Let’s see a possible implementation of the parametric approach.At the heart of ArchiCAD there is a powerful technology – GDL. This three letter abbreviation stands for Geometric Description Language. GDL has been developed specially for ArchiCAD to describe 2D and 3D elements in a user-friendly parametric programming environment. GDL objects are stored in external libraries; the objects are called library parts in ArchiCAD. Each library part contains several text-based scripts dedicated to different purposes, including 2D symbol, 3D model and description for quantity take-offs.Whenever a GDL object is inserted into an ArchiCAD project, only a reference to the external library part is saved with the file. However, users have the option of saving the project as an archive, which also stores the library parts in the file.The following pictures show the many configurations of the same GDL stair object.



HIGHLIGHTS OF GDLUsing GDL has many advantages not only for BIM users but for all participants of the AEC industry:• Flexibility and Control: GDL objects can be used on both MacOS and Windows, and are able to export product data

in common CAD file formats, including DXF and DWG, and the emerging industry standard IFC.• Integration with Building Design: The selection of building components during the design phase benefits both the

designer, who can use real-life objects in their design, and the component manufacturers, who can successfully market their product at an earlier stage in the design process.

• Product placement: Manufacturer's information is included in the GDL object information, which means that product-specific information is available not only to the designer, but the facilities manager and all other building professionals who need access to such information throughout the building's life cycle.

• Cost savings: GDL is an open standard and easy to learn and use, so the initial development and maintenance costs are low. Additionally, data conversion is automatic, so there is no need to recreate information in different formats such as DXF and DWG.

• Optimized for the Internet: Thanks to its parametric nature, GDL creates objects that are easy to access and easy to manage on the Internet. The maintenance of GDL-based electronic product libraries requires little effort, which means it is easy to keep information on the website up to date.

This illustration shows how different manufacturer’s products can be inserted and compared in the running project.

WHAT CAN YOU DO WITH GDL?GDL objects offer the optimal way of describing building components for use in construction design and facility management applications.GDL can describe:• 2D symbols:

– Markers– Zones– Annotations

• Building elements:– Doors, Windows– Stairs

• Furniture and equipment• HVAC elementsand much more.



GDL BASICS: PARAMETERS

Let’s have a quick overview of the main features of GDL. Probably the most important attribute of GDL objects is that they can contain several parameters. Parameters define values, properties and variations of a product. They are used to control the 2D, 3D and the user interface parts of the object. Users are free to define different types of custom parameters for GDL objects.The following parameter types are available:• Length• Angle• Real number• Integer• Boolean• Text• Material• Line type• Fill pattern• Pen color• Separator• TitleA parameter’s name and description are also editable.

GDL BASICS: 3D SHAPES

The 3D geometry and behavior of an object is determined in the library part’s 3D script. GDL provides dedicated commands to describe basic 3D shapes in the 3D script. 3D commands use these definable parameters to adjust the object’s main dimensions and surface materials.



In addition to the basic shapes like bricks, cylinders or spheres, GDL can describe more complicated forms like extruded, revolved or mesh-type objects.

GDL BASICS: 2D SYMBOLS

The 2D representation of an element is described in the object’s 2D script. Special 2D commands help the users to define parametric 2D symbols with options to change the shape, pen color, line type or fill pattern.

GDL BASICS: TRANSFORMATIONS

A very important attribute of 2D and 3D shapes in GDL is that they are defined in their own local coordinate system. While the local coordinate system can be moved, rotated or even distorted, the general coordinate system always remains at the same position. All the elements that were defined in the local coordinate system will follow its changes, so the 2D and 3D shapes can be freely transformed in space or on the plane.

GDL BASICS: GRAPHICAL EDITING

Users can also modify the length and angle type parameters of a library part from the floor plan and 3D windows. The special points (hotspots) defined in the object’s 2D and 3D script can be grabbed and adjusted with the mouse. The parameters assigned to these points will automatically get their values from the graphical user interaction.



GDL BASICS: GRAPHICAL USER INTERFACE

In addition to its parametric capabilities, GDL also provides a friendly environment for working with parametric objects. • Scrollable parameter list: A complex element, such as a window, can easily contain more than 100 parameters.

Extensive parameter lists are scrollable, and parameters can be set as bold, title or pop-up types.• Graphical User Interface: The object's custom user interface makes it easier to set parameters and values when using

objects describing real products.

• Preview Image: The object’s preview image is used for faster access, e.g. when viewing a large catalog or browsing in the library.

• Product Info URLs: GDL stores URL links to a manufacturer's web site. Dynamic product data (i.e. specifications and data sheets) can easily be located via GDL objects.

FREE GDL TOOLS

The following products offer the ability to use GDL objects in different environments and usage scenarios, targeting many aspects of the building, construction and manufacturing industry: GDL Adapter for AutoCAD

With GDL Adapter, you can work with intelligent and parametric GDL objects in the AutoCAD and ADT environments. GDL objects can be placed into the 2D and 3D workspace using a simple drag and drop operation. Once placed, objects can be edited at any time, including modifications to color, material or any other parameter setting. GDL objects work inside AutoCAD as common AutoCAD blocks.GDL Explorer

GDL Object Explorer is a utility application for viewing GDL objects and full GDL catalogs without having to install ArchiCAD or ArchiFM. GDL Explorer offers the ability to visualize and save objects in other file formats, such as DXF, DWG, DGN, 3D Studio, Art*lantis Render, Lightscape, VRML, SVF and Wavefront.GDL Web Control (Plug-in)

GDL Web Control provides ways of exploring GDL objects via the internet using popular web browsers. It allows technical design data to be easily communicated using parameters, 2D/3D views and CAD connectivity.GDL Publisher

GDL Publisher is an authoring tool for publishing GDL objects on web pages. Publishing a GDL library can be as simple as placing it on a web server, or as complex as writing thousands of HTML pages and data files. It all depends on the composition of the library and the quality expectations of the publisher. To get immediate results, you just need to use GDL Publisher.



GDL DOCUMENTATION

Several learning tools are available for learning GDL:• The GDL Reference Manual, included on the ArchiCAD CD, contains the complete list of commands and the

detailed description of the GDL syntax.• Beginners who may not want to jump into scripting can find useful information in the Introduction to Object

Making PDF document. • Those who want to learn how to create more advanced parametric objects with scripting can refer to the GDL

Cookbook. • Finally, professional library developers can read the GDL Technical Standards document for Graphisoft’s object

standards.

SOURCES OF GDL LIBRARIES

Users can get GDL libraries from many sources:• The ArchiCAD library contains more than 1000 highly parametric objects covering all fields of the AEC industry.• Free GDL objects can be downloaded from several websites on the Internet• You can also find commercial web pages offering large collections of GDL objects• The GDL engine can import 2D and 3D objects in many popular CAD formats including DXF-DWG and 3DS.



• Several manufacturers of building elements have already released their product line in GDL format. These objects can be downloaded free from the manufacturers’ website.


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bim_curriculum12_lecture_09_parametric object technology.pdf