ISO code list. Ensure use of the most current version of this document by searching British Standards Online at bsonline. BSI Amendments issued since publication Amd. Project data structured as a series of planar 2D models 3 Figure 2?
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ISO code list. Ensure use of the most current version of this document by searching British Standards Online at bsonline. BSI Amendments issued since publication Amd.
Project data structured as a series of planar 2D models 3 Figure 2? Drawing definition incorporating views of multiple model files 3 Figure 3? Instances of a sub-model of a component within a model file and model file references 3 Figure 4?
Example of coding of 2D model file field names 7 Figure 5? Example of node and insertion point placement 8 Figure 6? Example of sub-set layer coding using only mandatory fields 10 Figure 7? Example of layer coding using both mandatory and optional fields 10 Table 1?
The applicability of alternative data structuring methods 6 Table 2? Recommended order or usage of model file field names 7 Table 3? Mandatory fields and recommended character codes 9 Table 4? Optional fields 10 Table B. Differences between international and British layer naming fields 13?
It supersedes BS which is withdrawn. The changes incorporated in this new edition reflect the increased use of reference files and greater experience of CAD data management and exchange. It was prepared in parallel with ISO and recommends the use of a simpler, ISO compatible, layer naming and coding strategy. This minimizes the number of different layers used and reduces complexity when data are exchanged between different parties to a project.
A British Standard does not purport to include all necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. At the same time, and in some cases in advance of the development of commercially available systems, the BS EN ISO series of standards for the exchange of product STEP modelling data are being developed to provide a neutral means of describing construction product data throughout its life-cycle, independent from any particular CAD software system.
When fully available, object-orientated programming, distributed databases and product modelling will not only enable the transfer of data to take place between all participants in the design and construction process, using different software systems, but will also form the basis for structuring and sharing component libraries, databases and archives.
This guide was written to accommodate a 4 digit element code which may not be compatible beyond level 2 with some of the newer classification systems, e. Uniclass . Although the recommendations in this standard are primarily intended for users and managers of CAD systems, it is expected that developers of such systems will support the implementation of this standard.
Guidance is given in annex A, on project organization and neutral format data exchange. Guidance on layer name fields and coding conventions for international projects is given in annex B. This guide covers conceptual classes of information important to construction industry users, methods of structuring CAD data and recommends coding rules and conventions for naming model files, sub- models and layers.
Guidance is also given on drawing annotation, presentation and the management and exchange of data between CAD users. An important use is also to structure data in component libraries produced by third parties. This standard does not include guidance on the use of different data exchange file formats, the exchange of non-graphic data, structuring and exchange of data held as object classes and their instances, data structuring appropriate to specialist engineering analyses, or the definition and use of data entity parameters parametrics.
For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies. BS , Construction drawing practice? Recommendations for general principles.
Recommendations for symbols and other graphic conventions. Recommendations for landscape drawings. BS General and miscellaneous? Operations; associated plant and equipment? NOTE The following terms defined in this standard are reproduced, the first time they appear in clauses 4 to 11, in bold type. Together, these model files form a graphical database of project information. CAD systems may also store, manipulate and output non-graphic data relating to graphic entities.
However, at present, the data structures of most systems are not designed to record explicit information about the relationships and interdependencies that exist between parts of a project, or the parts and the whole. Organizations tend to adopt one of two main approaches to project modelling for the production of drawings. They may: a build up project data as a series of planar 2D models, typically relating to plans, sections, and elevations, by discipline and from these construct separate 3D models from which to produce perspective visualizations see Figure 1 ; or b adopt an approach more akin to product modelling, build a 3D model or models as assemblies of entities representing construction components, and assemble drawings incorporating 2D or 3D views of 3D model data see Figure 2.
The choice of which approach or mix of approaches to adopt is likely to depend on individual project requirements and the capabilities of the CAD system or systems being used. Each organization should understand why they are adopting a particular approach in a project. Where CAD data is to be exchanged with other organizations, the approach adopted for the production of drawings may need to be altered to accommodate other members of the project team. Project data structured as a series of planar 2D models Figure 2?
Drawing definition incorporating views of multiple model files? It records the information necessary to create a specific drawing.
Typically, it will store annotation drawing number, name, revision notes, dimension strings, etc. As a minimum, a drawing definition will specify the position and scale at which such views are to be displayed and plotted. A 3D specification also includes the view point, the depth of view, and the type of perspective employed. The graphic entities held in model files are usually assigned line styles and other parameters affecting their appearance when they are created, but when defining a view users may be permitted to specify that graphic entities be displayed in a different way.
Most important, and most variable between systems, are the methods offered to structure, and then control, what categories of graphic information are displayed. Figure 2 shows a drawing definition that incorporates a 2D view of information assembled in a model file, which in turn refers to information stored in other model files.
Model file references can be used to: a layer model information in the same fashion as overlay drafting; b assemble a composite model from a set of component models, with little data redundancy; c create drawing definitions and make templates of information which are common to models and drawings e. CAD systems which support reference files usually also support instances of sub-models see 5.
Some systems also permit nested file references see 8. Sometimes sub-models are stored as separate files and are referred to in much the same way as other model files but often the information associated with a sub-model is stored within the substructure of a model file and is only referred to within the file see Figure 3.
Nearly all CAD systems use some combination of the data structuring methods described below. Although it is not uncommon to store all the graphic data relating to an individual drawing in a single file, many CAD systems also allow a user to open one file as an active file and then simultaneously display and interrogate, read-only data in other files. Each file is referred to by a reference inserted into the active file which records the name of the referenced file and its position, size and orientation in relation to the active file.
It may also include a specification of which layers within the reference file should be displayed see 5. Figure 3?
Instances of a sub-model of a component within a model file and model file references 4? Sub-models are also generally distinguished by the special treatment they receive. For example, libraries are designated to hold them, special provisions are made to view them for selection purposes, to count them, and to assign, schedule and report on the non-graphic attribute data associated with them. By design, they are ideally suited to represent individual construction components or discrete assemblies of such components.
Sub-models and the entities they contain are often assigned separate layer attributes see 5. Object oriented CAD systems use objects to fulfil the role played by sub-models of components. This usually occurs when an entity is created. Entities with the same assigned layer attribute then form a layer. Layers are generally named or numbered and an entity can be transferred between layers by changing its layer attribute assignment.
Layers of 2D graphical data are similar in concept to the transparent sheets used in overlay draughting, with all the entities relating to the same co-ordinate system. Unlike reference files, all information is held in a single file and layers formed in this way cannot be clipped or included by reference in other files. The visual display of a layer can , however, be turned on and off. Layering can also sometimes be used to designate which entities should be ignored during editing operations, although in practice, the selective manipulation and editing that can be performed on layers is usually quite limited.
If faceted names such as: architect, level 2, plan, etc. Some CAD systems also allow wildcarding techniques to be used to specify which categories of model data should be displayed or manipulated.
Model files, sub-models, and objects can often be handled in a similar fashion by systems that support their faceted naming, or selection based on attribute assignment. They can be classified into the following categories.
Each discipline usually maintains its own models which contain data covering its particular area of responsibility. Usually one discipline takes the responsibility for a base or framework model upon which the others rely. Almost inevitably there is some duplication of information so that co-ordination between disciplines can take place. Increasingly models of building stock are being used by strategic divisional planners and managers within organizations. Although perhaps not the original authors of the data, their job function and the fact that they might be the most enduring users of the graphic database may mean that their requirements should take precedence.
This can be information associated with plotted output, such as drawing borders and drawing annotation, or to produce views for drawing composition purposes which contain only a subset of the information contained in one or more model files. It may also be information which users working on models wish to display or suppress for their own convenience. Because plan levels commonly form the nucleus of a graphical database, it may often be necessary to subdivide a plan model containing all information concerned with a particular level of the building to satisfy multi-user access requirements and system response times.
Section and elevation planes which hold quite different data and which are updated on a different basis are often kept as separate models.
Other concepts may also be important, particularly the subdivision of data by construction phase or contract work package. Creating new building stock, or adding to and refurbishing existing property, can stretch over long periods of time, and may well progress through various development and approval stages. Phases blend one into the other. Predictions on future phases, operations on current phases and audit trails on past phases, all have their influences on model structure.
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