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Collision Detection - choosing the best solution

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Community Manager

collision detection components.jpg

Siemens PLM Software develops three distinct software components for ISVs to support collision detection in their 3D software applications:

Parasolid offers full 3D modeling capabilities in addition to collision detection. Parasolid customers and prospects should first review the extensive capabilities that Parasolid offers and consider D-Cubed CDM and KCD only if their specific application would benefit from the integration of one of these complementary solutions designed specifically for collision detection applications.

D-Cubed CDM supports B-Rep and facet models, and is often selected for high performance collision detection on B-Rep models in motion simulation environments.

KCD is optimized for very high performance and low memory usage in facet-heavy motion simulation scenes and point cloud models.

All three technologies have evolved separately to target different applications, but offer similar capabilities. This article helps you to identify which components are best suited to your application.

We’ll consider the similarities and differences in terms of three categories:

  • Geometry model
  • Functional coverage
  • Computation speed


Collision Detection – Geometry model

Various types of 3D model representation have evolved for 3D design, simulation and manufacturing applications, including:

B-Rep solid – precise mathematical model suitable for high accuracy engineering design and manufacturing.

Facet mesh – less accurate polygonal mesh data, often created from point cloud data and used in high performance digital mock-up, gaming and animation.

Point cloud – set of data points in 3D coordinate space, typically scanned from real-world objects.

Our components support collision detection on various combinations of these formats. You can refer to the table below to determine which components are best suited to your choice of geometry model:


  Parasolid D-Cubed CDM KCD
Facet data
Point cloud   1 2
B-Rep solid, sheet and wire bodies  
Tolerant to geometric inaccuracies
1D-Cubed CDM computes closest approach between point cloud and B-rep
2KCD computes collision and closest approach between any combination of point cloud and facet data


File format interoperability

Parasolid provides interoperability with a very wide range of B-rep model formats through Parasolid end-to-end translators and HOOPS Exchange. Initial Parasolid Convergent Modeling functionality also supports the import of facet data for use in modeling operations.

D-Cubed CDM is designed to reference your own choice of data model(s), so no particular modeler is required and it’s possible to perform collision detection on data sourced from multiple formats in the same environment. An interface is available for rapid integration with Parasolid-based applications.

KCD operates on any triangular mesh, in addition to point clouds, capsules and rays, and can be extended to support user-defined types. Interfaces are available for popular formats including JT, STL, STEP and VRML.


Collision Detection – Functional coverage

Some applications have fairly simple requirements and only need to verify whether objects are colliding in a static model, for example, after importing or repositioning parts in an assembly. Further analyses may reveal the extent of collision (depth or volume of penetration), or provide repositioning information to remedy a collision (solve-to-touch). Applications may also need to determine the clearance between two parts (closest approach) or predict potential collisions on a given trajectory (collision along a path). The following table provides a comparison of the capabilities provided by each component.


  Parasolid1 D-Cubed CDM KCD
Identify collisions (interpenetrating entities)
Depth of penetration  
Volume of interpenetration    
Containment (one entity lies entirely inside another)
Abutment (entities touch each other)
Solve to touch  
Closest approach (minimum distance between entities)
Maximum distance between two entities    
Intersection lines  
Collisions along a path   2 3
Compute collision-free path     3
Transmit motion between parts coming into contact   4  
1Parasolid functionality applies to B-Rep models, some restrictions on facet models apply
2D-Cubed CDM support linear paths only
3With KineoWorks component
4With D-Cubed AEM component


Collision Detection – Computation speed

Computation speed depends on the depth of analysis required. All three components offer more rapid tests for evaluating the occurrence of collisions, with the option to extend the computation to identify more detailed information about the colliding entities.

The type of geometry model is an additional factor for consideration in terms of performance. Computation speed on a facet model is likely to scale better than computation on an equivalent B-Rep model when the quantity and complexity of freeform surfaces increases.

Kineo Collision Detector and D-Cubed CDM are optimized for performance in motion simulation applications and so they are more suitable for collision analysis on moving parts. This is why some existing Parasolid customers have licensed one of these additional components for expanding their collision detection functionality.

All three components are thread-safe, enabling multiple tests to be performed at the same time, and can take advantage of parallel processing to increase performance by running the same test in simultaneous threads where applicable. Furthermore, KCD will use all available cores to deliver very high performance in facet-heavy motion environments, where collision detection and closest approach queries can be performed simultaneously on multiple parts moving in the same scene.


Additional Considerations

Finally, it’s worth considering the broader role of PLM Components in your application.

  • If you have no long-term requirement for Parasolid’s broader design/edit/interop features, then your focus should be on D-Cubed CDM or KCD.
  • If you work predominantly with facet models and you anticipate a future requirement for KineoWorks to perform dynamic, automated path planning, KCD could be your best option for collision detection.
  • If you foresee requirements for full physical motion simulation using D-Cubed AEM, D-Cubed CDM might provide you with a better development path.

To discuss your collision detection needs in more detail, please contact us using the link below: