BIM & LiDAR Survey Technology on Site
Point-cloud survey and a federated BIM model are changing how discrepancies between design and as-built conditions get caught, and when.
A drawing shows what was intended. A site rarely matches it exactly, and the gap between the two is where most variation orders come from. Laser scanning closes that gap earlier than a tape measure and a site diary ever could.
On a typical fit-out or retrofit, a LiDAR scan of the existing structure produces a point cloud accurate to a few millimetres. That cloud is registered against the architectural and structural BIM model, and any clash between what was drawn and what was actually built shows up as a flagged discrepancy before a single wall is opened up, rather than after.
The practical effect is fewer surprises mid-programme. A beam that sits fifteen millimetres off its drawn position, a slab that is not quite level, a services run that clashes with a proposed ceiling void: these get caught in the model, on a screen, in a design review, instead of on site with trades standing around waiting for a decision.
We now scan as a matter of course on any retrofit or fit-out where the existing structure is not fully documented, and federate the result into the same model the architectural, structural and MEP teams are already working from. It costs a day or two up front. It has saved considerably more than that in abortive work on every project we have used it on.