Student Project Highlights Best Practices in BIM Workflows
This summer, George Brown College Students worked with Esri Canada to explore BIM conversion workflows. Through a series of tests, the students studied how to pass georeferenced models between Autodesk Revit and Esri ArcGIS Pro.
This summer, two George Brown College students worked with Esri Canada to explore BIM model cross-compatibility between Autodesk Revit and Esri ArcGIS Pro.
Roya Lashanizand and Mohammed Atif, students in George Brown’s postgraduate Building Information Modelling Management (BIM) Program spent a semester learning about BIM conversion and GIS, and exploring workflows to move BIM data between Revit and ArcGIS Pro while maintaining data integrity. Under the supervision of Professor Petro Karanxha and David Kossowsky at Esri Canada, Roya and Mohammed conducted a thorough review of technology capabilities and opportunities and generated a report and 3D web scene to showcase their research.
Two main research questions formed the basis for their project:
- Would data loss occur when moving between Revit and ArcGIS Pro, and could the same Level of Detail (LOD) be maintained throughout this workflow?, and
- After loading a model into ArcGIS Pro, could a BIM’s georeferenced coordinates be exported, and re-imported into Revit to create a spatially geo-referenced BIM model in a Revit workspace?
Project Initiation
The project began by generating a BIM model of George Brown’s campus building from an unstructured point cloud scan. Using 3D point processing software, the point cloud was cleaned, registered and brought into Revit. Here, an LOD200 form was generated which included exterior walls, floors, stairs and roofs. Since this model was created in a cartesian coordinate space, the resultant form contained no geographic reference points.
Point Cloud Data
LOD200 BIM Model
Data Conversion Testing
The following tests were performed to check if the Revit BIM could be imported correctly into ArcGIS Pro, and automatically georeferenced.
Test 1 – Import directly from Revit file
The LOD200 BIM was exported from Revit and the .rvt file was imported into ArcGIS Pro. While the building displayed correctly, it was placed at a 0,0 coordinate because the file was lacking a geographic coordinate system. To correct this issue, manual georeferencing would be required. Additionally, this method resulted in significant attribute data loss.
BIM Imported at 0,0 coordinates
Test 2 – Import directly from Revit file with accompanying projection (.prj) file
The George Brown campus is situated in Toronto, Canada. This geographic location corresponds with the projected coordinate system of WGS 1984 UTM Zone 17N. To accommodate this, a .prj file was generated in ArcGIS Pro and added to the folder containing the Revit file. The Revit file was then imported into ArcGIS Pro. As a result, the model was positioned closer to the correct location, but was still lacking precise spatial accuracy, and significant data loss was still occurring.
BIM missing data after manual georeferencing
A UTM Zone 17N projected coordinate system file was exported from ArcGIS Pro
Test 3 – Setup a geographic coordinate system in Revit before importing into ArcGIS Pro
This method required more manual work, but resulted in the most accurate output.
First, coordinates and elevation for the George Brown campus building were recorded from ArcGIS Pro using the Locate tool, and a building rotation angle was calculated with the Measure tool. These coordinates, elevation and angle were then entered into Revit and used to set model control points and a true north angle.
Once coordinates were assigned in Revit, the model was brought back into ArcGIS Pro along with the accompanying .prj file created in test 1. The model imported to the correct location, and was now ready for conversion into a format that was easier to work with, and publish, in ArcGIS Pro.
As a final step, the model was converted into a Mutipatch format by running the “Run BIM File to Geodatabase” geoprocessing tool in ArcGIS Pro. The resultant model was converted into an easily editable Esri format, located correctly, and Revit property data were maintained and converted into attributes that could be queried, filtered, and symbolized as needed.
BIM model with correct placement
Comparing model to aerial imagery
Enhancing the BIM Model
Once the building was correctly placed on site, additional contextual data could be added to enhance the 3D scene. The City of Toronto’s Open Data Portal provides 3D massing models for the entire city. A selection of 3D massing models were brought into ArcGIS Pro to add surrounding building context, and the scene’s basemap was adjusted to suit the visualization.
Finally, the model was published to ArcGIS online and shared as a custom web application for interactive, online viewing.
A custom web application was created to showcase the BIM model
Findings and Future Considerations
The original goal of this project was to test whether a BIM model could easily be brought from Revit into ArcGIS Pro, and then back into Revit. While there is a fairly clean method to import Revit models into ArcGIS Pro, a process to pass a model back into Revit does not exist yet. It is possible that this could be achieved through a custom FME or Dynamo workflow, but this method was not tested during this project.
Additionally, the students noted the importance of checking for accuracy during point cloud conversion, as any errors during conversion could result in much larger model issues relating to data integrity.
Finally, it should be noted that ArcGIS Pro 2.6 now directly reads textures from Revit files. This enhancement, and others relating to BIM updates, can be found here in ArcGIS Pro’s 2.6 release notes.
Conclusion
Roya and Mohammed set out to answer two research questions through their testing and research approach:
- Would data loss occur when moving between Revit and ArcGIS Pro, and could the same Level of Detail (LOD) be maintained throughout this workflow?
As long as the data are converted into a Geodatabase format after import, then data loss should not occur.
- After loading a model into ArcGIS Pro, could a BIM’s georeferenced coordinates be exported, and re-imported into Revit to create a spatially geo-referenced BIM model in a Revit workspace?
A model can be exported from Revit into ArcGIS Pro and positioned with an accurate spatial location, but it is currently not possible to pass a model from ArcGIS Pro back into Revit. This may be possible through a custom script and workflow creation in FME and Dynamo.
For more information, Roya and Mohammed’s full report can be viewed here.
Additional Resources
For additional information about importing BIM into ArcGIS Pro, check out the following resources:
How to Georeference Revit Data in ArcGIS Pro
About the Authors
Roya Lashanizand is a post-graduate student in the Building Information Modelling (BIM) Program at George Brown College. Over the last year, Roya has been focused on BIM Management, where she has studied principles and applications of BIM processes in Integrated Project Delivery (IPD) frameworks from conceptualization to facilities management. Roya’s interests lie in the Architecture, Engineering and Construction (AEC) industry, where she continues to expand her skills in architectural 3D modelling, and learning about ways to improve the efficiency and effectiveness of BIM implementation in AEC projects.
Mohammed Atif is a post-graduate student in the Building Information Modelling (BIM) Program at George Brown College. Mohammed has a degree in civil engineering, and prior professional experience in the GIS and engineering field. Through the BIM program at George Brown, he is expanding his professional education by learning about collaborative BIM platforms and tools. With an interest in AEC technology applications, Mohammed is now looking to apply his skills in GIS, BIM, and civil engineering within the GIS and urban planning industry.
Petro Karanxha is a professor in the Building Information Modelling Management Program at the Angelo DelZotto School of Construction Management at George Brown College in Toronto, Canada. He teaches BIM Management, Computer Applied Construction Practices, BIM Software Integration, BIM Implementation Strategies, and BIM Project Planning. Petro’s areas of specialization are in Building Information Modelling, BIM Management, Navisworks, Revit, SketchUp and LiDAR technologies.
This post was translated to French and can be viewed here.