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About this Block

What it does: The CAD Body from Implicit Body block converts an input Implicit Body to a CAD Body. This block is useful for exporting parts made in nTop back to other CAD software, as a Parasolid (X_T, X_B) or STEP file (.STEP), using the Export Part block. Common uses:
  • Convert implicit to CAD Body
Tips
  • We recommend this block for medium complexity models. See the Part Complexity section below to understand how to categorize the complexity of your part. This block produces NURBS surfaces that are not aligned with the part’s features, but it’s more likely to succeed on medium-complex models where the quad meshing workflow would fail.
  • For highly complex models, we recommend using the Simplified Body Representation block.
  • For low complexity models, use the CAD Body from Quad Mesh block. See Procedure 1 in this support article for a full overview and example nTop file.
  • The optional Preserved CAD input lets you provide a list of CAD Bodies, and the block will attempt to sew-in faces from the CAD Bodies into the final result. If the face extends outside of the boundary of the implicit, or if the algorithm didn’t succeed in sewing, the face will be ignored. Preserved CAD Input
  • For a complete overview of export workflows, including what data types and blocks to use for each particular downstream activity, see this article.

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Part Complexity

In this context, complexity relates to the number of CAD faces required to represent an implicit body. This determines the usability of the model within traditional CAD systems.

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Low

Parts that are generated from Topology Optimization, unfilled shells, and parts with very coarse patterns or ribs. These usually require only a few hundred to a few thousand CAD faces to represent their geometry. Low complexity example

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Medium

These are parts with medium-coarse textured models or lattices containing beams, faces, or TPMS cells:
  • Beam or face-based lattices: up to 10k beams or faces
  • TPMS: up to 1k unit cells
Implicit models at this level of complexity can be converted into CAD Bodies with 50k or fewer faces, so their detailed geometry can be consumed by traditional CAD systems. Medium complexity example

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High

These are parts with fine-grain textures, beam or face-based lattices with over 10k beams or faces, or TPMS lattices with over 1k unit cells. Typically, these require many thousands or even millions of CAD faces, so their detailed geometry can not be used by traditional CAD systems. High complexity example

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Example File

Download Example: CAD Body from Implicit Body Example Screenshot
Converts an Implicit Body to a CAD Body within a specified Tolerance. As the Tolerance increases, the CAD Body may contain fewer faces and be generated faster. Works best for medium complexity Lattices and Implicit Bodies. For lower complexities, use Mesh from Implicit Body, Quadrangulate Mesh, then CAD Body from Quad Mesh. For higher complexities, use the Simplified Body Representation block.

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Inputs

NameTypeDescription
BodyImplicit BodyImplicit body to convert to a CAD body.
ToleranceScalarThe maximum allowable distance deviation of the CAD body from the implicit body. As this value increases, the CAD body will have fewer faces and generate faster, but deviate further from the body. We recommend starting with a value of approximately 1/2 of the body’s thinnest feature.
Preserved cadCAD Body ListOptional list of CAD bodies. When provided, the block will attempt to stitch the CAD faces from the preserved CAD into the final output. Faces that are not entirely contained on the surface of the body will be ignored.

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Outputs

Type
CAD Body