Unlock BIM Efficiency: Automating Clash Detection with Dynamo

The Challenge

Clash detection is a notorious bottleneck in the AEC industry. Ever spend hours manually detecting clashes in a massive Revit project? Many will relate to the familiar frustration of these repetitive tasks, thinking, "there's got to be a better way!"

This was the reality for CLL, a company specialising in large scale construction solutions, who approached Cadpro with a complex Revit piling project with thousands of elements. The traditional workflow approach to clash detection/solution with federated models is incredibly slow and tedious, and they were looking for a better, more efficient way forward.

Repetitive tasks, automated solutions

The clash detection process had become a monotonous cycle for CLL: identify a clash, adjust element geometry, rinse and repeat. Cadpro identified that repetitiveness a prime candidate for automation through scripting, and proposed the use of Dynamo for Revit: a visual programming tool embedded within Revit, that empowers users to build custom scripts (called Dynamo graphs) in minimal time. Cadpro saw an opportunity to streamline CLL’s workflow by developing a Dynamo graph that could automatically identify clashes, and then intelligently adjust specific geometric parameters of the involved Revit elements to resolve the intersections.

Challenges of brute-force clash detection

While Dynamo for Revit offers powerful automation capabilities, Cadpro knew that a common pitfall during script development is relying on brute-force clash detection. This method involves testing every element against every other element, leading to an explosion of variable calculations, especially in large projects. Imagine a project with just 3,000 elements – testing all possible combinations could result in millions of intersection checks. Even at a hypothetical rate of 100 clashes per second, this could take hours to process. Furthermore, projects constantly evolve, requiring frequent clash detection throughout the design process. During the development phase of a Dynamo graph, testing and refinement are crucial. A slow script would significantly hinder this iterative process. A more efficient solution is essential.

Cadpro addressed the limitations of brute-force testing by implementing a more sophisticated approach within CLL’s Dynamo graph, leveraging Dynamo's strength in handling bounding boxes and their intersections. Bounding boxes are essentially simplified envelopes around elements, and Dynamo can perform intersection checks between them extremely fast compared to complex geometries. By employing a bounding box filter as a first step, CLL's script significantly narrowed down the elements that could potentially clash. This is because the bounding boxes act as a preliminary screening tool, identifying elements in proximity that might have actual clashes. While some level of brute-force testing is still required after the filter, it drastically reduces the overall number of intersection checks needed.

The impact of this approach was remarkable. In a test with 8.5 million potential clashes, CLL's Dynamo graph utilising bounding box filtering was able to detect and resolve actual clashes in just 90 seconds. This represents a staggering 99.6% reduction in processing time compared to the 23.5 hours required without this optimisation.