By Andy Davis

Autodesk AutoCAD Plant 3D with kubit PointSense Plant

Background

The number of new-build process industry projects in development is decreasing and is likely to continue to do so.  Instead, plant owners are looking to increase capacity and reduce costs by improving the performance of existing facilities.  These brown-field projects usually require the modification of existing process pipework necessitating the removal of existing pipelines and the addition of new lines that must tie-in to the existing plant.

Traditionally, this has required considerable time and effort to accurately model the existing area of plant to be modified – through line-walking, measuring and then drawing in CAD.

However, the rapid development and democratisation of laser scanning technology has provided a relatively quick and in-expensive way to capture images of the real-world in 3D.  By combining (registering) multiple scans, a comprehensive 3D view of a plant can be created as a cloud of points in 3D space.

The point clouds that are produced from the laser scans can be recognised by CAD applications and used as a source of co-ordinates for modelling purposes.  Currently, there is no push-button solution for creating a CAD model directly from a point cloud, so designers must manually remodel the plant in CAD by fitting CAD objects to the points in the cloud.

The Toolset

Using AutoCAD Plant 3D together with kubit’s PointSense Plant add-in to AutoCAD, enables accurate AutoCAD Plant 3D piping models to be created directly from a point cloud without manual drawing.

kubit PointSense Plant provides pattern recognition tools that can identify plant assets directly from point cloud data.  Exact tie-in points for components can also be determined without any modelling.

However, before this can happen, the laser scan files of a site must be registered and combined into a unified point cloud that can be recognised by AutoCAD. 

Large point clouds are not easily managed due to their size because of the volume of data they contain.  However, Autodesk ReCap provides an efficient mechanism for managing these large datasets using its RCS and RCP file formats.  ReCap also provides necessary functionality to enable a section of a unified point cloud to be clipped out and exported to a smaller, more manageable file.

Autodesk ReCap

AutoCAD (and kubit PointSense Plant) support several point cloud file formats including ReCap RCS and RCP files and AutoCAD’s default PCG format.

Point cloud images of objects from a laser scan are not always easily recognisable and can be difficult to interpret when viewed in AutoCAD.  kubit VirtuSurv provides an almost photorealistic 360 degree panoramic view of a laser scan file together with macro facilities for transmitting the co-ordinates of points from the photorealistic image directly to AutoCAD.

kubit VirtuSurv

Any AutoCAD Plant 3D CAD models that are created during the modelling process can be viewed in the context of the original point cloud using Autodesk Navisworks.  Navisworks can combine point cloud and CAD files into a unified model for aggregation, visualisation and review purposes.

The Workflow

A possible workflow for creating a model of process pipework from a laser scan consists of 3 stages: preparation of the initial scan files prior to modelling, the modelling procedure itself and finally a review stage.

These stages are summarised below:

Preparation

• Scan the site and register the scan files.
• Create a ReCap project from the scan files – one RCS file per scan file combined into a unified RCP project file.
• Create a VirtuSurv project from the original scan files – for use during modelling to help identify fittings and show realistic detail of connections between fittings.
• Create initial Navisworks model files from the scan files for use during review.

Modelling Procedure

• Use ReCap to divide the unified scans into smaller, manageable areas – clip as necessary and export PCG files of small areas for use by kubit PointSense Plant within AutoCAD Plant 3D.
• Create kubit models of each pipeline as required using PointSense Plant together with VirtuSurv as required. 
• Export the kubit models to AutoCAD Plant 3D objects within the AutoCAD Plant 3D drawing.

Review

• Create a Navisworks model of the existing scan files (NWD format) and append the AutoCAD Plant 3D DWG files for visualisation and review.
• Use the Switchback feature of Navisworks to switch back to AutoCAD Plant 3D as required.

Summary 

As-built AutoCAD Plant 3D models of process pipework can be created directly from laser scan images of existing plant using AutoCAD Plant 3D together with the kubit PointSense Plant add-in to AutoCAD for pattern recognition and kubit VirtuSurv for visualisation. 

To facilitate this, large laser scan projects can be managed, clipped and exported to smaller point clouds using Autodesk ReCap. 

Finally, Autodesk Navisworks can be used to review the models within the point cloud.