What is the best workflow to go from point cloud scans to Revit models for historic buildings?

[infoWBN4V]

Hi everyone.

I would like to know what workflows are there available to process in Revit (or in some third party software) point clouds from 3d scans of historic buildings in order to bring all the information into Revit in a way that allowed us to treat the scanned geometry as floors, roofs, walls, doors or any other Revit standard element. The workflow might combine manual and automatic processing, but avoiding the manual part as much as possible to shorten the process.

I have already watched several videos of third party softwares (i.e. Edgewise) but they mostly work with simple geometries (pipes, straight walls etc). Ancient buildings have very irregular geometries instead (some of them are even ruins) due to decades, or even centuries, of decay. Walls with different thicknesses and inclines, domes with large deformations due to persistent loads, heterogenous composite materials combining stone, brick, mortar and other components are just some of the most common situations we encounter.

The purpose of this workflow is to have these complex geometries in Revit for a better interaction with newer geometries coming from restoration/extension projects of those historic buildings. These irregular geometries should be entitled to have some parameters and Revit should be capable to calculate their volumes or use them to calculate room areas for instance. Also they should be able to be sectionable and viewable like any other model geometry.

That's it. 🙂

Thanks so much. 

[constantin.stroescu · Accepted solution]

  I have worked with Heritage Building (most buildings from middle age time) using 3d Scan.

Not an easy task...

 While studying the problem I was able to draw a few conclusions that were presented in a conference  that took place last summer at a workshop dedicated to heritage buildings and virtual reality.

Below, you can see an excerpt from my study (google translated), showing 3 methods of approach to the subject, by using as base the Points Cloud:

1. BIM with parametric modeling

If the built object does not have large deviations from the intended geometry, then the 3d modeling is done in the same way as in the case of designing new constructions using parameterized elements. The parameterized elements specific to HBIM, in general, cannot be found in the current databases in the virtual environment.

The creation of data banks containing families of parameterized objects dedicated to historical eras or architectural sites requires a concerted and major effort that involves sustained team work.

We mention two examples here:

a project to create libraries of digital objects parameterized in accordance with the principles of architectural grammar from Europe and Ireland in the 17th-18th centuries - promoted by the University of Dublin

o the JHBIM project - the library of parameterized digitized objects dedicated to the medieval urban heritage of Old Jeddah in Saudi Arabia.

The 2d-CAD drawing can either take the intentional geometry (the result will be similar to the classic measures) or the exact situation in the field using the local sections through the Point Cloud as landmarks-

Plans, Sections and Elevations. The problem that arises here is the impossibility of generalization (a section is only valid for the area in which it was made)

When drawing BIM 3d modeling elements, it is preferable to use orthogonality based on the idea of ​​supporting the intention of the project and not the real situation.

How do we decide if we can follow the line of intent of the project or the deviation from orthogonality and accuracy is too big and then we have to do a non-parametric modeling with personalized modeling.

pros:

• The advantage of the method consists in the fact that the whole project being modeled, the assembly can be controlled by parameters and we are dealing with real BIM

cons:

• the process requires a large amount of work to create the existing database, a longer time to complete and involves the creation of a consistent database of parameterized elements

2. BIM modeling with the use of non-parameterized elements created in the basic software (Revit)

If the deviations from the intended geometry are major, BIM-type modeling becomes complicated ... it can be done using nonparametric elements. However the process allows control of the geometry and allocation of non-geometric information that can be used in the operational phase of the asset.

. pros:   

• It can solve the problem of 3d modeling and object geometry.

• Allows the use of modeling software: specialized 3d non-specific BIM process (Rhino, Fusion360, 3dsMAX)

cons:  

• working with non-intelligent, purely geometric elements, it is necessary that they be incorporated into an AEC software in order to assign them a series of limited parameters.

3. Use of Meshes, created externally and imported into the work software (Revit) with the attachment of non-geometric parameters.

If, due to major imperfections, the BIM modeling process becomes unviable, the method of creating Meshes - triangulated surfaces can be used.

For this, geometry recognition tools are used so as to transform the result of the 3D scan (Point Cloud) into the geometry of triangulated surfaces.

This transformation process is automatically generated by specialized software (Faro-As-Built, EdgeWise) This solution does not create intelligent AEC elements, but allows visualization and through post-processing in AEC software, the attachment of non-geometric parameters.

In the case of restricted areas, it is possible to "extract" the Mesh from the Point Cloud using the Scan to Mesh module, incorporated in Recap PRO

. pros:  

• It solves the problem of a highly accurate geometric modeling that transforms the Cloud of Points into triangulated Mesh Surfaces.

cons:

• Mesh creation is based on expensive software
• Obtaining a Mesh from the Point Cloud requires high processing power and a long time.
• The result of the conversion leads to the creation of large files.
• The conversion software is still in the development phase

• I can also indicate some reference studies I've consulted and I think they are important to understand the process:

https://www.autodesk.com/autodesk-university/class/Discovering-History-BIM-Project-Notre-Dame-2019

https://medium.com/autodesk-university/parametric-modeling-of-vaults-for-notre-dame-in-revit-7a9b0d6...

https://arrow.tudublin.ie/cgi/viewcontent.cgi?article=1072&context=beschreccon

https://www.autodesk.com/autodesk-university/class/Point-Historic-Preservation-Point-Clouds-Old-Buil...

https://historicengland.org.uk/research/results/reports/6747/TheApplicationofBuildingInformationMode...

https://www.researchgate.net/publication/286534560_Parametric_accuracy_Building_information_modeling...

[infoWBN4V]

Awesome.
I'll dig into it.
Thanks so much.