Should Laser Scan Models be Orthogonalised?

3D models developed from laser scan point clouds can be very accurate. So accurate, in fact, that 2D drawings derived from such models can appear rather untidy. To counter this, the laser scan model can be “orthogonalised”, so that slight angular imperfections in otherwise perpendicular joints (e.g. from sagging pipes) are corrected.


The snapshot below shows a section of pipe before and after the orthogonalisation process:


The differences may appear fairly minor to the naked eye, but the resulting isometric drawings highlight the true differences.

(a) As scanned isometric


(b) Orthogonalised isometric


In our experience, many Clients tend not to like the as-scanned piping drawings purely on aesthetic grounds – they simply don’t look very nice. However, the chief drawback with orthogonalised models is that the pipes can no longer be dimensioned properly since real-life angular imperfections have been corrected. This raises practical questions about what is important in an as-built dimensional drawing and perhaps even deeper questions about whether such drawings are even required when a 3D model or point cloud is available.


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