eBIM Process

eBIM Process

Scope & Specification

BIM Scope & Specification

An eBIM asbuilt survey requires a clear understanding of the client’s role and what the model will be used for as this will effect the survey method and modelling accuracy and detail. This requires a project kick off meeting prior to starting the laser survey, so that a model can be delivered that meets the overall project’s aims.

LEVELS OF DETAIL:

The appropriate level of detail is critical when developing a BIM model.

That is why we have developed a standardized specification split up in to different LODs:

  • LOD 1 – Basic Massing Model
  • LOD 2 – Shell & Core Model
  • LOD 3 – Standard Survey Model
  • LOD 4 – Detailed Survey Model
  • LOD 5 – Detailed Survey Model with meta data

Please email info@ebim.co.uk to request a copy of our specification.

 

 

STANDARD DETAIL INCLUDED IN LOD 3 MODEL

• Internal partitions up to ceiling height
• Internal / external walls / floors at visible level
• Sanitary fittings – indicative
• Stairs
• Windows, doors
• Ceilings and bulk heads
• Railings, balustrade
• Primary Structure extent of visible area – columns, beams and trusses
• Visible secondary structure – columns, supporting curtain walling
• Floor Slabs and level changes
• Key MEP elements to be clarified on site

3D Laser Survey

Stage 1: POINT CLOUD SURVEY

We use a range of different scanners depending on the project in hand and required accuracy’s. Laser scanning provides fast accurate data capture of complex environments and shapes.

The scanner works by firing out a laser and for every surface that the laser hits, it records a 3 dimensional point in space (xyz value). This process is carried out 100,000’s of times a second generating a rich point cloud of data.

As the scanner can only scan what is in its line of sight, it can’t scan through objects (yet!) it has to be setup in multiple locations. To join all the individual scans together a control network of targets is placed around the site before the survey starts.

ADVANTAGES OF LASER SCANNING

Laser scanning is fast.

Our scans can capture up to 900,000 points of data per second. A typical scan can take just 3.5 minutes! This means that site time is reduced dramatically.

Laser scanning is accurate.

Within a 25m radius each scan point is accurate to +/- 2mm!

Laser scanning is detailed.

Scan resolution can be as detailed as 1 point of data every 3mm. This means that it takes just the same time to scan a grade one listed facade adorned with intricate statues as it would any normal building, yet every single detail is picked up first time!

Laser Scanning is 3D

The point cloud that is generated from laser scanning looks like an exact 3D replica of the site. This makes it very easy to visualise complex older buildings.

The Modelling Process

Once we know what you will be using your eBIM model for, we can recommend the level of detail and accuracy to suit your requirements.
Our 3D laser survey creates a highly detailed POINT CLOUD, this provides a wealth of detail for the surveyor but can be difficult for other parties to interprete.

This is because of the sheer size of the point data. An individual scan even when heavily compressed is typically about 350MB in size (uncompressed it can be upto 1.5GB). A typical project of a house or shop on a couple floors would be about 50 scans, this equates to 17.5GB. Big projects can be up to 500 scans that’s 175GB!! If you’re working with point data then you need to have the right hardware and plug-ins in place to manipulate this amount of information.

The eBIM process is to convert this large point data into accurate parametric REVIT models, this way our clients can easily work with the survey results without the associated cost and training required to manipulate point data.

POINTCLOUDS IN REVIT

Using a number of techniques we can bring the point cloud data directly into Revit. Since the introduction of AutoCAD 2014 native poin tcloud support has been available using the Autodesk .rcs file format. Revit users can import a range of point cloud files and using RECAP convert them to this new native format. Once in Revit technicans can trace around the point data with Revit families quickly building up a 3D model using the point cloud as a reference.

Revit was not initially designed to model existing buildings, and although it is possible to model exactly to the scan data using inplace families, this is very time consuming and lacking in functionality. To this end we will normally make some assumptions in the modelling process and use standard Revit Families as much as possible (unless the client requests otherwise) For example slight deviations in walls etc will be straightened as long as we can retain at least +/-20 mm accuracy.

If you already have a set of company specific standards, please supply us with your generic template which will be used in confidence.

 

 

pointcloud_revit

MODELLING

To maximise our modelling efficency we use a number of cutting edge technologies. eBIM utilise the latest automatic feature recognition algorithms to automatically extract pipework direct from the point cloud, this is combined with the latest Revit point cloud plugins from Leica (Cloudworx) and in house point cloud Cylone server which has allowed us to optimize the modelling process, data sharing and storage.

Revit is not backward compatible so the desired version must be clearly stated at the outset. Although we work in Revit, clients using other software packages such as ArchiCAD or Vectorworks can receive data as a generic IFC model file.

 

 

polyline_extraction

 

 

Deliverables

We have 3 main deliverables from an eBIM survey. These are the 3D point cloud and viewing software, the finished 3D model and our web share our online collaboration and virtual site viewing software.

POINT CLOUD & VIEWER

We can provide you with the point cloud data in a range of formats. The most common one currently is an .rcs file. This is the Autodesk generic file format which can be opened using any Autodesk 2014+ product or using there free point cloud viewing software RECAP.

Older Autodesk users (2012-2013) can use the previous format .pcg however this has limited functionality compared to the newer file type and point cloud engine.

If required for archive purposes we can also issue the point cloud as a .e57 file. The E57 file format is a compact, vendor-neutral format for storing point clouds specified by the ASTM, an international standards organization, and it is documented in the ASTM E2807 standard.

REVIT MODEL

A full accurate as built Revit model will be provided to the level of detail requested in your specification and in a predetermined version of Revit (Revit is not backwards compatible so please check that all members of your design team are using the same version).

BUBBLE VIEW

Each laser scan setup generates a 360 degree image. This will be available in greyscale or in colour if photos have also been taken. We have a number of different ways to view this data using vendor specific viewers (Leica TruView, Faro Webshare) or bespoke web interfaces.

 

BIM Scope & Specification

BIM Scope & Specification

An as built eBIM & Revit survey requires more client interaction that a traditional 2D survey. In the past the client would issue a survey specification, this would provide a clear cut set of requirements and deliverables for the surveyors to produce.

More Info
3D Laser Survey

3D Laser Survey

We use a range of different scanners depending on the project in hand and required accuracy's. Laser scanning provides fast accurate data capture of complex environments and shapes.

More Info
The Modelling Process

The Modelling Process

Once we know what you will be using your eBIM model for, we can recommend the level of detail and accuracy to suit your requirements.

More Info
Deliverables

Deliverables

We have 3 main deliverables from an eBIM survey. These are the 3D point cloud and viewing software, the finished 3D model and our web share our online collaboration and virtual site viewing software.

More Info