Complete Guide to Wrapping Techniques for CAD Model Simplification

The transformation of complex CAD models into simplified representations has become a major challenge for manufacturing industries facing visualization, collaboration, and data protection challenges. With increasingly voluminous assemblies sometimes reaching several gigabytes, creating optimized envelopes (ShrinkWrap) provides an effective technical solution that significantly lightens these models while preserving their essential characteristics. This approach offers considerable performance gains, with reductions of up to 90% of the initial data volume, while maintaining a faithful visual representation.

Table of contents

• Fundamentals of ShrinkWrap transformation
• Applications and use cases
• Technical process of creating a ShrinkWrap
• Advantages and limitations
• The CADfix VIZ solution for envelope creation
• Best practices for model optimization

Fundamentals of ShrinkWrap transformation

ShrinkWrap, or "shrink wrapping," refers in computer-aided design to a geometric simplification process that involves generating an envelope around a complex 3D model. This technique creates a lightweight representation that preserves the general shape of the original model while significantly reducing its internal complexity and digital weight.

This method differs from other simplification approaches by its ability to maintain the external appearance of the model while eliminating internal details that are often superfluous for certain applications. Unlike classic decimation that uniformly reduces the number of polygons, ShrinkWrap generates a new "skin" around the model, offering a more intelligent and targeted reduction in complexity.

Different types of available envelopes

The industry has developed several variants of envelopes, each adapted to specific needs in terms of simplification and fidelity:

• Box Wrap: Most simplified form, creating a simple bounding box that retains only the maximum external dimensions. This method offers maximum complexity reduction while preserving the general encumbrance.
• Convex Wrap: Generates a convex shape encompassing the model, without hollows or concavities. This intermediate approach preserves more of the general silhouette while significantly simplifying the geometry.
• Shrink Wrap: Produces an envelope that more faithfully follows the contours of the original model, preserving most important external characteristics while eliminating internal details.

The choice between these different methods directly depends on the compromise sought between lightness and representational fidelity, as well as the intended final application.

Applications and use cases

ShrinkWrap transformation addresses concrete needs in many industrial sectors. Its growing adoption is explained by the diversification of digital applications requiring optimized 3D models:

Visualization and display performance

Native CAD models, often consisting of millions of triangles, can significantly slow down display performance, even on powerful systems. Converting to ShrinkWrap improves visualization fluidity during collaborative sessions, design reviews, or client presentations, where performance takes precedence over access to the model's internal details.

Virtual, augmented, and mixed reality (VR/AR/MR)

Immersive technologies impose severe constraints in terms of performance, particularly on mobile or standalone devices. Simplification through ShrinkWrap allows adaptation of complex industrial models to these demanding environments, making possible the virtual exploration of complex assemblies, immersive technical training, or contextual visualization in augmented reality.

Intellectual property protection

When sharing models with partners, suppliers, or customers, companies often wish to protect their know-how by limiting access to internal design details. ShrinkWrap offers an elegant solution by creating a faithful external representation while removing sensitive information about internal structure, assembly techniques, or patented technological solutions.

Preparation for simulation and analysis

Certain preliminary analyses do not require all the details of the CAD model. Simplified envelopes allow for considerably faster calculations of aerodynamics, thermal behavior, or space requirements, reducing preparation and execution times for simulations while providing relevant results for preliminary project phases.

Technical process of creating a ShrinkWrap

Generating an optimized envelope on a CAD model generally follows a structured process in several key steps, requiring a methodical approach to ensure the quality of the final result:

Preparation and analysis of the source model

Before any simplification, an evaluation of the original model is necessary to identify its essential characteristics, complexity, and critical areas to preserve. This preliminary analysis helps guide parameter choices and the wrapping method.

Preparatory steps typically include:

• Identification of critical components requiring faithful representation
• Detection of small elements that can be filtered or merged
• Geometry evaluation to detect potential anomalies that could affect the process
• Classification of subassemblies according to their functional or visual importance

Selection of components to transform

In a complex assembly, not all components require the same level of simplification. Modern tools allow for selective approaches:

• Transformation of the entire model with uniform parameters
• Targeted application on specific subassemblies
• Automatic filtering of small components by defining a size threshold
• Differentiated processing according to the visibility or functional importance of elements

Wrap parameter configuration

The quality and efficiency of the result directly depend on the chosen parameters, particularly:

• Envelope type: Box, Convex, or Shrink depending on the fidelity/simplification compromise sought
• Minimum triangle size: directly influencing the resolution of the resulting mesh and therefore the precision of the envelope
• Small element management: filtering thresholds to ignore or group components of reduced size
• Geometric tolerance: defining the maximum acceptable deviation between the envelope and the original model

Validation and quality control

After generating the envelope, a verification phase is necessary to ensure that the simplified model meets the requirements:

• Visual comparison with the original model to verify geometric fidelity
• Analysis of dimensional deviations at critical points
• Verification of the topological integrity of the resulting mesh
• Evaluation of gains in terms of file size and display performance

Advantages and limitations

ShrinkWrap transformation offers substantial benefits but also presents certain limitations that should be considered before adopting this approach:

Major advantages

• Spectacular reduction in file size: Depending on the type of envelope and chosen parameters, volume reductions can reach 90% to 99%, transforming models of several gigabytes into files of just a few megabytes.
• Improved graphic performance: The decrease in the number of triangles directly translates to smoother visualization, allowing manipulation of complex assemblies even on modest hardware.
• Intellectual protection: By removing internal details, the company can share its models without exposing its technical know-how.
• Simplified workflow: Preparing models for downstream applications (virtual reality, simulation, documentation) becomes considerably faster and less resource-intensive.

Limitations to consider

• Loss of internal information: By nature, ShrinkWrap eliminates the internal structure, making it impossible to access individual components or assembly details.
• Geometric approximation: Even with the finest parameters, the envelope remains an approximation of the original surface, potentially introducing dimensional deviations.
• Unsuitability for certain analyses: Structural simulations, detailed thermal analyses, or tolerance analyses generally require the original models rather than their simplified envelopes.
• Limited subsequent modifications: Models converted to envelopes can generally no longer be modified parametrically like native CAD models.

The CADfix VIZ solution for envelope creation

Among the professional solutions available on the market, CADfix VIZ stands out for its ability to efficiently simplify CAD models while preserving the essential characteristics required for visualization and analysis.

Main features

CADfix VIZ offers a structured and intuitive approach for generating optimized envelopes, with a set of features specifically designed to meet industrial needs:

• Intuitive interface for wrap creation: The user environment allows easy configuration of envelope parameters without advanced CAD expertise
• Interactive and automatic processing: Allows both batch operations and precise, targeted adjustments
• Support for numerous CAD and mesh formats: Ensures interoperability with most CAD systems on the market
• Preservation of attributes: Retains important information such as colors, layers, and hierarchical structure

Wrap creation options

The CADfix VIZ interface offers several application modes to precisely adapt to the specific needs of each project:

• "All/selected bodies" mode: Allows applying the wrap to the entire model or only to selected entities, offering maximum flexibility to treat certain components differently
• "Small bodies" mode: Intelligent filter that automatically targets small components based on a configurable threshold (28.0 units in the standard interface), effectively eliminating superfluous details while preserving main structural elements

Available envelope types

CADfix VIZ implements the three main envelope methods, each adapted to a specific level of simplification:

• Box Wrap: Creates a parallelepipedic envelope that preserves only the external dimensions of the model ("keep min. detail"). This option offers maximum simplification and is perfectly suited for space studies or schematic representations.
• Convex Wrap: Generates a convex envelope that further preserves the general shape of the model ("keep less detail"). This intermediate option offers a good balance between simplification and visual recognition.
• Shrink Wrap: Produces an envelope that more precisely follows the contours of the original model ("keep more detail"). This option is ideal when a more faithful representation is needed while significantly lightening the model.

Advanced control parameters

To ensure optimal results, CADfix VIZ allows fine-tuning of several technical parameters:

• Minimum triangle size: This fundamental parameter (adjustable to 9.35 units in the standard interface) determines the granularity of the resulting mesh, directly influencing geometric fidelity and final file size
• Interactive commands: The "Find," "Filter," and "Apply" buttons facilitate the process by allowing, respectively, identification of candidate components, filtering according to specific criteria, and application of the envelope with chosen parameters

Concrete benefits

Using CADfix VIZ for envelope generation brings measurable advantages to engineering teams:

• Drastic reduction in model size: Up to 90% weight reduction, allowing sharing and manipulation of models previously too voluminous
• Significant performance improvement: Display fluidity multiplied by 5 to 10 on complex assemblies
• Simplified workflow: Accelerated preparation of models for virtual, augmented, or mixed reality applications
• Extended accessibility: Intuitive interface allowing even users without in-depth CAD expertise to generate optimized envelopes

Best practices for model optimization

To maximize the benefits of ShrinkWrap transformation, here are some recommendations from industrial experience:

Choosing the envelope type according to the application

Adapt the simplification method based on the intended use:

• For preliminary space or layout studies: favor Box Wrap
• For collaborative visualization and design reviews: use Convex Wrap
• For commercial presentations or technical training: opt for Shrink Wrap

Optimized mesh parameterization

The quality of the result strongly depends on mesh parameters:

• Start with a triangle size adapted to the overall dimension of the model (generally between 5% and 10% of its smallest characteristic dimension)
• Perform comparative tests to find the best compromise between fidelity and lightness
• Consider different parameters for functionally important areas and secondary areas

Intelligent processing of small components

Small elements often contribute disproportionately to overall complexity:

• Use the size filter to automatically eliminate components below a certain threshold
• Group functionally similar small elements before applying the wrap
• Selectively preserve certain critical small components despite their size

Validation and quality control

Ensure the relevance of the simplified model through a structured validation phase:

• Visually compare the original model and the generated envelope
• Verify that critical dimensions and characteristics are properly preserved
• Test display performance in the target environment (VR, mobile, etc.)
• Document the parameters used to ensure reproducibility of the process

By following these recommendations and fully exploiting the capabilities of tools like CADfix VIZ, companies can effectively integrate ShrinkWrap simplification into their digital workflow, thus addressing the growing challenges related to the complexity of modern CAD models.