Features
Topology
DGK supports the construction of a CAD style topology consisting of bodies, surfaces, curves and vertices overlaying
the faceted model. In addition to helping maintain associativity with parametric models, this strategy is key to
supporting many advanced modification and repair operations.
Model Construction
Create primitives: boxes, cylinders, cones and spheres.
Bottom up: create vertices, construct smooth curves from selected nodes and vertices, construct surfaces from
selected curves.
Extrusion: Extrude a surface in a prescribed direction.
Booleans: Addition, subtraction and intersection.
Curve stitching and embedding
Curves consisting of points that may or may not be part of the surface can be projected and embedded into a surface.
This is essential in defining feature curves that cannot be identified by simpler strategies for example, angle based
feature detection.
Curves can be stitched together to resolve tolerance errors or to close large gaps.
Surface and Curve refinement and coarsening
Surfaces and curves can be refined with options to project new nodes on the original geometry or to reconstruct a
smooth geometry using 4th order C1 interpolations. Sizing can either be prescribed for each individual node,
calculated to preserve a smooth grading or interpolated from boundary curves.
Surfaces and curves can also be coarsened to eliminate all edges below a prescribed size or according to an angle
criterion. The coarsening algorithm is useful in removing extremely small edges from the model, for reducing the size
of models while maintaining a user specified accuracy or, in conjunction with the topology tools, removing unwanted
features from the model.
Surface smoothing and blending
Xtl offers two types of smoothing - Laplacian and curvature based. Laplacian smoothing is more aggressive while the
curvature based algorithm can remove remove high frequency errors while minimizing its impact on the overall shape
of the surface.
The blending tool smoothly rehapes a surface to achieve tangent continuity with its surrounding surfaces.
Translation, scaling and rotation
These operations can be applied to selected bodies, surfaces and curves or to individual nodes.
Wrapping
Wrapping algorithms are a volumetric approach to STL repair and are often preferred for highly complex dirty
geometries for which traditional tools are not sufficient. They are typically used when a closed manifold surface is
required as is typical for simulation or for 3D printing. DGK contains a prototype intelligent wrapping algorithm that
is capable of closing large gaps while preserving small features.
Our wrapper has successfully solved problems that are not easily addressed using any other automated algorithm.
However it is still a prototype and is currently best applied to smaller models (less than 1 million facets) that are the
result of laser scans. We are working to extend the technique to models originating from CAD systems.
General repair
Hole filling : automatically identify and fill holes in selected bodies or surfaces.
Repair normals.
Calculate surface intersections
Disconnect surface: Disconnects a surface from surrounding surfaces so that it can be independently modified.
Low Level Tools
DGK contains many low level functions and classes that aid in developing your own algorithms. These include:
- insert node on edge or face, swapping, node deletion.
- search trees for closest point and bounding box searches
- basic geometric calculations (intersections, distance).
- projection to surfaces.

Copyright 2014 Discretize Inc.

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Our Xtl app, built on
DGK, was selected as
Desktop Engineering’s
Editors Pick of the week
for July 6 2011