How to convert OBJ
to IGES?

The OBJ format is a popular and widely used file format for representing 3D geometry. It was initially developed by Wavefront Technologies for their Advanced Visualizer software. OBJ files store information about the vertices, faces, texture coordinates, normals, and material properties of a 3D model.

This format supports the representation of polygonal geometry, making it versatile for a wide range of applications. OBJ files are widely supported by various 3D modeling, animation, and rendering software, making it easy to share and exchange 3D models across different platforms and workflows.

Support of OBJ files in CAD Exchanger

CAD Exchanger can import files with external .mtl (material library) files, files with both multiple and single parts, and export files. Such support includes:

• polygonal representations;
• colors, materials, textures.

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Pros of the format

Universality

One of the key advantages of this format is its widespread compatibility. OBJ files can be imported and exported by a vast number of 3D modeling, animation, and rendering software applications. This broad support allows for seamless collaboration between different software packages, making it easier to share 3D models across various platforms and workflows. Whether you're working with industry-standard software or niche tools, chances are high that they will support the OBJ format.

Simplicity

The OBJ format is known for its simplicity and ease of use. OBJ files are plain text files, making them human-readable and easily editable. This simplicity makes it straightforward to manually modify or create OBJ files using a basic text editor if needed. Additionally, the file structure of OBJ is relatively straightforward, consisting of vertices, faces, and associated information. This simplicity makes it accessible for beginners and allows for quick understanding and integration with other software pipelines.

Cons of the format

Limited Geometry Support

This format has some limitations when it comes to representing complex geometry. OBJ is actually a polygonal format, so B-Rep is not supported as a class, neither for a simple cylinder nor for super-complex geometry. As a result, OBJ is not suitable when there is a need for B-Rep, and not polygonal meshes. This can be a disadvantage when working with models that require precise curved surfaces or complex mathematical representations.

Lack of Animation and Rigging Data

Another drawback of the OBJ format is that it does not inherently support animation or rigging data. OBJ files primarily focus on static 3D geometry representation and lack the ability to store information related to skeletal animation, rigging, and dynamic simulations. It also lacks several features like support for lights, LOD settings, and advanced materials. This makes it less suitable for complex animated scenes or character animations that require bone structures, joint deformations, or motion data.

FAQ

Is OBJ format specification publicly available?

Yes, it is. The OBJ file format specification defines the structure and organization of OBJ files. OBJ files begin with a list of vertex data, which consists of coordinates (X, Y, Z) that define the geometry of the 3D model. Texture coordinates (U, V) can also be included to map textures onto the model's surfaces. Normal vectors (X, Y, Z) define the orientation of the surfaces.

Faces are defined using indices that reference the previously defined vertices, texture coordinates, and normals. Groups and smoothing can be specified to organize the model's faces and define the shading and smoothness of adjacent faces. Additionally, OBJ files can reference material libraries (MTL files) that define properties like color, reflection, and transparency for the model's surfaces.

What are the typical .obj file extensions?

The OBJ file format is usually associated with two file extensions: .obj and .mtl.

.obj is the primary extension for OBJ files. It represents the 3D geometry data, including vertex coordinates, texture coordinates, normal vectors, and face definitions. The .obj file contains the essential information required to represent the shape and structure of the 3D model.

.mtl is a companion file to the OBJ format. It contains information about the material properties applied to the surfaces of the 3D model, such as color, reflectivity, transparency, and textures. The .mtl file is referenced by the OBJ file to assign materials to different parts of the model.

How to open a .obj file?

To open this file, you will need a compatible software application, for example, CAD Exchanger Lab. Launch the software and navigate to the 'New file' option. Browse your computer's directories and locate the .obj file you want to open. Then select it and click "Open". Once the import process is complete, the .obj file should be loaded into the software, allowing you to view and interact with the 3D model and associated data.

History of the OBJ format

The OBJ file format has a rich history in the field of computer graphics. It was originally developed by Wavefront Technologies, a company known for its pioneering work in 3D computer graphics and animation software. The OBJ format was first introduced in the late 1980s as part of Wavefront's Advanced Visualizer software, which was widely used in the film and entertainment industry.

Wavefront designed the OBJ format to provide a standard way to exchange 3D models between different software applications. It aimed to address the interoperability challenges that arose due to the diverse range of 3D modeling and animation software available at the time.

As the OBJ format gained popularity, it became widely adopted by the computer graphics community. Its simplicity, versatility, and support for geometry, texture, and material data made it a favored choice for sharing 3D models across various platforms and software packages.

The OBJ format has been embraced by numerous 3D software applications, making it a de facto standard for exchanging 3D models. Despite the emergence of newer formats, OBJ remains widely used and supported due to its long-standing history, compatibility, and ease of integration into different workflows. Today, the OBJ format continues to play a significant role in the world of 3D computer graphics.

The IGES format was developed to provide a universal standard for exchanging 3D data between different CAD software applications. IGES files, represented in ASCII text, contain information about the geometry, structure, and attributes of 3D objects.

The IGES format enables users to share complex CAD models while preserving the integrity of the data. It supports the representation of both 2D and 3D geometries, allowing for the exchange of points, curves, surfaces, and solids.

Support of IGES in CAD Exchanger

CAD Exchanger can import IGES format files up to version 5.3, export IGES format files version 5.3. Such support includes:

• B-Rep representations;
• assembly structure;
• names;
• user-defined properties;
• colors;
• layers.

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Pros of the format

Broad Compatibility

IGES has been a long-standing industry standard for data exchange since its development in the late 1970s. Many CAD systems, both old and new, have built-in support for importing and exporting IGES files. This enables easy collaboration and data sharing between different software platforms, regardless of the specific CAD system being used.

Good capabilities for B-Rep representation

For a format that is over 35 years old, IGES provides good capabilities for representing B-Rep and even representing rigid bodies, including information on connectivity. Combined with the advantages indicated above, it makes the IGES format relevant and actively used to this day.

Cons of the format

Limited representation of B-Rep geometry

The IGES format has some limitations when it comes to fully representing B-Rep geometry. While it can effectively preserve basic geometric information like points, curves, and surfaces, there are difficulties with edge connectivity information. Most CAD writers use the older and limited capabilities of representing B-Rep through bounded and trimmed surface entities. These entities can not contain comprehensive information about the surface topology of bodies. As a result, models written in this form often have inconsistent edge orientations.

No PMI

The IGES format does not have a standardized way to represent or store PMI data. As a result, when exporting a CAD model with PMI to an IGES file, this valuable information is typically lost or not accurately transferred. This limitation can have significant implications for downstream processes, as manufacturers may rely on PMI data for carrying out manufacturing operations, quality control, and documentation.

To overcome the weakness, newer formats, such as STEP, have been developed to support the inclusion and preservation of PMI data. These formats provide dedicated mechanisms to store and communicate PMI information, allowing for a more comprehensive exchange of design intent and manufacturing specifications.

FAQ

Is IGES format specification publicly available?

Yes, it is. The IGES file format specification defines the structure and syntax of IGES files, ensuring consistency and compatibility.

Header section contains general information about the file, such as software details and creation date. Start section defines the units of measurement, coordinate system, and other global parameters. Global section describes the overall structure of the file, including directories, lists, and relationships between entities. Directory section serves as an index for entities, assigning unique numeric identifiers and specifying their location within the file. Parameter data section contains the geometric and topological information of entities. Terminate section marks the end of the file.

What are the IGES file extensions?

The file extensions used for the IGES file format are ".igs" and ".iges". Both extensions are widely recognized and can be used interchangeably to indicate files that conform to the IGES format.

How to open IGES file?

To open an IGES file, you will need a compatible software application such as CAD Exchanger Lab. Start by launching the software and navigate to the 'New file' option. Next, find the IGES file (.igs or .iges) you want to open. Once you've located the file, simply select it and click "Open". The software will then initiate the import process, and once it's complete, the 3D model and its associated data will be loaded into the software. From there, you can easily view and interact with the 3D model.

History of IGES format

The history of the IGES format dates back to the late 1970s when it was developed to address the need for a universal standard for exchanging 3D CAD data. At the time, there was a lack of interoperability between different CAD systems, making it difficult to share and collaborate on designs.

To overcome this challenge, the National Bureau of Standards (now known as the National Institute of Standards and Technology) initiated the development of IGES in collaboration with industry leaders. The goal was to create a format that would allow for the seamless exchange of geometric and topological data between different CAD systems.

In 1980, the first version of the IGES format, known as IGES 1.0, was published. It provided a standardized structure and syntax for representing 3D CAD data, allowing for the transfer of geometric entities, attributes, and relationships. Over the years, subsequent versions were released, introducing enhancements and addressing the evolving needs of the industry. Today, the most widely used version is IGES 5.3, which was released in 1996 and is still in use today.

While newer formats have emerged with improved capabilities, IGES remains relevant, particularly for legacy systems and situations where basic geometric exchange is the primary requirement.