In solid modeling and computer-aided design, boundary representation—often abbreviated as B-rep or BREP—is a method for representing shapes using the limits. A solid is represented as a collection of connected surface elements, the boundary between solid and non-solid.
Boundary representation of models are composed of two parts: topology and geometry (surfaces, curves and points). The main topological items are: faces, edges and vertices. A face is a bounded portion of a surface; an edge is a bounded piece of a curve and a vertex lies at a point. Other elements are the shell (a set of connected faces), the loop (a circuit of edges bounding a face) and loop-edge links (also known as winged edge links or half-edges) which are used to create the edge circuits. The edges are like the edges of a table, bounding a surface portion.
Compared to the constructive solid geometry (CSG) representation, which uses only primitive objects and Boolean operations to combine them, boundary representation is more flexible and has a much richer operation set. In addition to the Boolean operations, B-rep has extrusion (or sweeping), chamfer, blending, drafting, shelling, tweaking and other operations which make use of these.
Parasolid is a widely used 3D geometric modeling kernel developed by Siemens PLM Software. It is a powerful file format that stores and represents 3D CAD models with great accuracy and precision. Like any kernel, Parasolid also has a persistence format known as Parasolid-XT. This format is specifically designed to transmit the B-Rep geometry of the model.
CAD Exchanger can import files starting from v0.15 and up to v35 and export files from v12 to v35. Such support includes:
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The primary advantage of Parasolid-XT lies in its kernel-based architecture. When you need to import data into CAD software running on the Parasolid kernel, opting for this format is a wise decision. As a kernel format, Parasolid-XT excels in its handling of B-Rep geometry, demonstrating exceptional proficiency in storing intricate B-Rep models encompassing solids, sheets, wireframes, mixed components, and even non-manifold topologies.
A notable advantage over the ACIS-SAT format is its capacity to represent the model hierarchy, albeit with some limitations (parts and bodies are somewhat synonymous). Nevertheless, in essence, the conversion to Parasolid-XT has the potential to preserve your part-assembly hierarchies, adding to its appeal as a preferred choice.
Another notable capability is the endorsement of hybrid models, specifically those in which a single logical component encompasses both B-Rep and mesh geometry. While this scenario currently represents a relatively small portion of real-world data exchange, it's gaining popularity. Consequently, the Parasolid kernel has been actively advancing to embrace these models, with the most recent iterations of the Parasolid-XT format designed to handle them.
Parasolid is a proprietary format owned and developed by Siemens PLM Software. This means that the specifications of the format are not publicly available, and only licensed software developers can fully access and utilize the features of Parasolid. While many CAD software applications support the import and export of Parasolid files, the lack of public specifications can limit the ability to develop custom tools or work with the format outside of the licensed software ecosystem.
Parasolid-XT offers some support for metadata and visual attributes, including the ability to name entities, assign colors to shapes, utilize layers, and user-defined properties as key-value pairs. However, if you're dealing with multi-body parts, PMI, or advanced metadata, it might be more beneficial to consider using alternative formats like STEP or JT. These formats provide more extensive support for those specific requirements.
The Parasolid format offers exceptional interoperability, and precise B-rep modeling ensures high geometric accuracy, making it suitable for complex engineering and design tasks. It also supports parametric modeling, enabling easy design modifications, and provides a wide array of geometric operations.
The Parasolid format finds extensive use in various industries due to its versatility and precision. Industries such as aerospace, automotive, manufacturing, consumer electronics, medical devices, architectural and construction, oil and gas, and gaming and entertainment all rely on Parasolid for 3D modeling and design. Its broad adoption across these sectors facilitates the development of everything from aircraft components and automotive designs to medical implants and video game characters.
CAD Exchanger does not support extremely rare geometric types, such as parabolas, hyperbolas, cpc curves, and others. These geometric types are exceptionally uncommon and rarely encountered in practice, and CAD Exchanger may ignore them if encountered.
There are occasional issues with offset surfaces on G1-continuous B-Spline surfaces. CAD Exchanger also can't export non-manifold topology, which occurs when an edge is shared by three or more wires or faces. In such cases, the exporter may drop some or all faces that refer to these shared edges. Non-manifold topology can be complex and is not always supported in Parasolid format.
In Parasolid, two primary file extensions are commonly used. The first one is .x_t (Parasolid Text), which represents a text-based format. It stores 3D geometric data in a text format, allowing for easy interoperability between different CAD systems. The second extension is .x_b (Parasolid Binary), which represents a binary format. .x_b files contain the same geometric information as .x_t files but in a more compact and faster-to-process binary format.
The Parasolid format has a rich history starting from its development by Shape Data Limited in the early 1980s. It was initially created as a 3D geometric modeling kernel and quickly gained recognition for its robustness and versatility. In 1996, the company was acquired by Unigraphics Solutions Inc., which eventually became part of Siemens PLM Software. Since then, Parasolid has continued to evolve and adapt, keeping up with the ever-changing demands of the CAD industry.
With its powerful capabilities and efficient representation of 3D geometry, Parasolid quickly became a standard format for CAD software developers. Its widespread acceptance can be attributed to its reliable performance and seamless interoperability. Many leading CAD software applications, including Siemens NX, Solid Edge, and SolidWorks, incorporate Parasolid as their underlying kernel, allowing users to create, modify, and exchange complex 3D models with ease.
Over the years, Parasolid has played a vital role in various industries, such as automotive, aerospace, and consumer goods. Its precision and accuracy have made it an indispensable tool for designers and engineers, enabling them to tackle intricate designs and perform detailed analyses. Today, Parasolid remains a cornerstone in the CAD landscape, empowering professionals to bring their creative ideas to life in the virtual world.
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