Point Cloud To BIM – The Process

Michael Gallie & Partners have over 50 years’ expertise in carrying out measured building surveys and over the last 5-10 years specialised in providing point cloud to BIM surveys. Below is an outline guide of our process.

The Process

1.       Access & RAMS

At Michael Gallie & Partners, we take gaining access to all areas of the building as important as the survey itself. With occupied buildings, the client would be provided a program for how long each floor takes to measure so access can be arranged accordingly. A Risk Assessment & Method Statement (RAMS) would also be provided prior to any on-site surveys.

2.       Survey Control Framework & Grid/Datum Setup

All our point cloud to BIM surveys are based upon an accurate survey control framework. To relate the survey to Ordnance Survey grid and datum our surveyors use 2 No. high accuracy GPS receivers on-site simultaneously for a 2-hour period.

3.       Laser Scanning

At Michael Gallie & Partners, we only use laser scanning for all our point cloud to BIM surveys. All areas of the building are fully laser scanned to ensure complete coverage. This involves a surveyor with a laser scanner mounted on a camera tripod carrying out multiple static setup positions across each floor typically for 1-2 minutes at a time. For some types of survey, we sometimes use a mobile hand-held laser scanner on-site for rapid but less accurate data collection. If you require a colour/RGB point cloud the site time for each static setup increases by at least 1 minute per setup.

4.       Office Processing to Produce Point Cloud

Using specialist software and high-end specification computers, the laser scan data collected on-site is then processed and registered to the relevant site grid & datum. The resultant registered point cloud is checked, verified and exported in manageable floor by floor chunks ready for the modelling process. Where required we also export the HDR colour/Greyscale images and/or point cloud taken by the laser scanner to create a TrueView of each setup position carried out on-site. TrueView is a web-based viewer software that documents the whole site conditions using measurable 360° pano-tour images taken from the laser scanner, an especially useful tool during the Covid-19 lockdown restrictions.

5.       BIM Production

The point cloud is then imported into the BIM authoring software i.e. Revit ready for the modelling process. Our modelling teams work collaboratively together on a single centralised model to avoid any repetition or modelling errors occurring. On each project the modelling team generally each work separately on different floors of the building and then synchronise back to the central model at suitable modelling milestones.

6.       Client Issue

All point cloud to BIM deliverables are issued to the client via a weblink download. All 3D models issued are accompanied with a drawing register which indicates model issued, versioning, date of issue and people issued.

If you need any advice on commissioning a point cloud to BIM survey, please contact Sam Lloyd at Michael Gallie & Partners who will be happy to assist you in this matter.

DETAILED BIM MODELS (LOD 3)