Getting Started 

BIM Navigation 

iTWO costX^® provides various methods to adjust the 3D Model view. These include zooming, panning and rotating drawings, hiding or showing only selected objects or layers, selecting a transparent or ghost view of objects, and moving through the building.

Importing Dimensions using a BIM Template 

There are various methods in which a user can extract dimensions from a BIM file. In this module we will learn how dimensions can be imported using a BIM Template.

BIM Templates are special macro / script files written by RIB for use with iTWO costX®. They are used to automatically import object property data from a BIM Model in accordance with a set of rules which determine how the Dimension Groups and Dimension Group Folders will be configured and which object property values will be imported. When dimensions are imported using a BIM Template, the Dimension Group Folders and Dimension Groups are automatically created based on the hierarchy grouping descriptions within the Model Tree, and the dimensions are automatically imported into them based on the most appropriate properties, therefore needing minimal user input.

Model Maps (PFC 5-5) 

A Model Map is a user defined ‘template’ which specifies how object properties contained within a 3D BIM Model drawing can translate into dimension information and automatically imported into iTWO costX®. A Model Map would normally be used to import dimensions where the user requires more control over the import process as compared to the BIM Import Template process, but still requires an automated process which can also be replicated. Model Maps may be set up at Global or Project level, and can also be copied allowing the establishment of Model Map templates if required.

In this module we will create a multi-tiered Model Map which will be used to import a variety of dimensions and will demonstrate how Model Maps can be used to:

1) Provide greater user control in the creation and naming of Dimension Group Folders and Dimension Groups to customize the BIM data output;

2) Utilize the model tree structure to create a Model Map which is applicable generally to the selected object group but also subdivides down into sub-group specifics;

3) Create formulas within a Model Map to calculate additional measurement information over and above that imported using a standard BIM Template or contained within the BIM Model properties.

Supplementary Take-off 

Having the 2D drawings in the same software means it is possible to supplement the 3D quantity take-off with additional 2D take-off using iTWO costX’s inherent features of polyline recognition, etc., if required. However, in this module we will undertake supplementary take-off from the 3D model. Supplementary take-off can be used to check the dimension group quantities if required. Supplementry take-off can also be used to allow for measurement where designers may not have included certain information in the model. Supplementary take-off can be achieved by using the following two methods:

1. 3D Measurement Mode

2. Object Mode Measurement

Revisions 

In this module we will create a new revision to the Building we have been working on and promote the 3D BIM drawing using a new revision. We will then learn how the dimensions are updated and the various methods of reviewing the changes between the revisions.

Quality Assurance 

It is important for us as quantity surveyors to go through and quality check our work regardless of which method of quantity take-off used (manual, 2D take-off or BIM extraction). With the BIM work-flow in place, Quality Assurance remains an important step of the process. In the following steps, we will outline a few tricks to help with the QA process and also identify typical issues that sometimes present in models.

Generating a Workbook 

Thus far, the training has outlined various methods of measurement from BIM models. Whilst these measurements can be dragged-and-dropped into workbooks in the normal manner this module will cover generating a workbook automatically based on the contents of the Dimension Groups. This is a powerful function, especially when the Dimension Groups can be linked to a matching rate library.

Introduction to IFC Files 

As stated in the Industry Foundation Classes (IFC) Files Section, IFC cannot replicate the authoring functions of the various proprietary BIM applications, nor is that its intention. The aim is to provide a broadly based, vendor-neutral exchange format for BIM Model data to facilitate:

1. Cross-discipline co-ordination of BIM models.

2. Data sharing and exchange across IFC-compliant applications.

3. Extraction and re-use of data for other downstream tasks associated with building ownership and operation.

The process of sharing data via the IFC format is termed an IFC Exchange. In practical terms, the need to convert the host data to IFC format and the fact that the IFC is structured to support a multiplicity of data types across a wide range of disciplines can lead to a high level of complexity in the IFC model. IFC exchanges therefore follow what is termed an “Exchange Requirement” which specifies the data that needs to be present in any given exchange and thereby limits the scope of the exchange so that different audiences can focus on the data relevant to them.

An associated IFC View Definition, or MVD (Model View Definition) defines a subset of the IFC schema that will satisfy the specified Exchange Requirements. Most IFC exchanges are therefore governed by an MVD. buildingSMART International official Model View Definitions (MVDs) releases are listed here. This includes exchange specifications for different IFC Schema, as well as those that have been accepted as international standards or are currently under development via the buildingSMART Standards Process.

When exporting an IFC file, IFC-compliant architectural BIM software maps the IFC export to the requirements of this definition. Because the main purpose of the Coordination View is to allow sharing of model data between the architectural, structural and MEP disciplines, the definition does not specify requirements for export of dimensions, so of itself the IFC will not contain quantities. However, dimension data available in the host application can be exported as a Property Set, but the designer must map the required data to the IFC as an export setting.

buildingSMART® have worked on defining model-based quantification of building spaces and elements, termed “Base Quantities”. These augment the IFC Coordination View definition by adding the ability to transmit Base Quantities for selected spatial, building, and structural elements, which get included in an IFC export as a tick-box option. Base Quantities are calculated from the model geometry in accordance with measurement definitions published by buildingSMART® and they may differ from model dimensions owing to different rules of measurement.

In this module we will review an IFC file exported from Revit® (both with and without Base Quantities), compare the data structure to a DWFx™ file exported from the same model, and generate quantities from the IFC model data.

Appendices 

In Module 9 we will review an IFC file exported from Revit (both with and without Base Quantities), compare the data structure to a DWFx file exported from the same model, and generate quantities from the IFC model data.