As Built Checks using Point Cloud Survey Data
As Part of the Government BIM strategy, It has been highlighted that to conform with PAS 1192-2:2013: "Appropriate surveys such as point cloud or LiDAR shall be provided to verify the completeness of the as-constructed model."
To comply with this we offer a fully comprehensive phased scanning of the building as it is constructed through various project phases. The result are point clouds which show an exact record of the building and the elements within it. These point clouds can be loaded into the Building information Model (BIM) and can be used to identify error or change allowing the BIM to be easily amended to match the as-built condition, or vice versa if the error hugely effects the following work.
We ensure that our 3D laser scan data is tied to to the original survey control or setting out points to enable consistent checking with as-built information. We set up chequerboard targets to prove scan position accuracy and vigorously check and adjust for near perfect scan alignment using various top of the range registration and indexing software.
Not only does this allow the contractor to prove what they have constructed is complete and that their as-built information is correct, but the point clouds provide a valuable future asset for the building. Should any future alterations be required to the building, the point cloud can be examined throughout various phases acting as a reliable source for clash detection of new proposed systems or can be used to find the best place to tie to existing structure which is no longer visible in the building due to suspended ceilings, or other finishes. This removes the need and additional cost for breaking out/making good surveys to establish size and position of building elements which are no longer visible.
As Building Information modelling has only recently become an industry standard, it is likely that current as built drawing information only exists in a 2D format. This isn't an issue for us, we can easily establish the point cloud position based on existing survey control, create the sections through the point cloud as we would in a standard 3D BIM model, then simply link the 2D information into the correct position. By setting a small view range through the section for example 50mm, we can quickly spot any deviation of point cloud data from the as built drawings provided.