The Complete IFC to IGES Conversion Guide

Geometry Compression Support:

IFC: Partial support | IGES: No support

IFC Notes:

IFC-ZIP provides compression for large models

Impact:

Geometry compression describes the process of compressing the representations of a 3D model's geometry, usually a triangle mesh. 3D geometry compression does not change the topology of a 3D model, but just changes the way that a 3D model and its 3D positions and related vertex data is stored. Geometry compression can be lossy (just like JPEG compression in image processing can be lossy, for example), in which case one might notice slight artifacts like variations in 3D vertex positions (compared to the uncompressed 3D model). However, such differences are often not noticeable. There are only very few standards for geometry compression, like glTF's support of Draco compression and similar extensions.

Texturing Support:

IFC: Partial support | IGES: No support

IFC Notes:

Basic texture support through material definitions

Impact:

Texturing describes the process or refining the visual appearance of a 3D model's surface through additional 2D or 3D data, defined in a different reference system. The by far most common use of texturing are 2D texture images, applied to model visual material properties the 3D surface. Other cases include the use of procedural 2D or 3D funtions that produce intensity or color signals, which are then mapped to the 3D surface. For the vast majority of these cases (all of them except for 3D procedural functions), a parameterization or "Texture Mapping" is needed, which maps the 2D content to the 3D surface. Coming from a 2D coordinate space with coordinate axes often entitled U and V (in contrast to XYZ, which are the 3D surface positions), this process of mapping is also called UV Mapping, and it can be done with a dedicated UV map, or through a live mapping (e.g., box mapping). In this example, a texture image is applied to the 3D model to give the control panel a realistic look. Without support for texturing, the panel would have to use a single material instead, or all controls (including text) would need to be modeled through 3D geometry, instead of a 2D texture image.

Materials Support:

IFC: Full support | IGES: Partial support

IGES Notes:

Basic material properties and annotations

Impact:

Materials are a fundamental concept in 3D modeling, enabling colored and - in many cases - photorealistic rendering of the 3D model that they are applied to. There are also some formats that don't make use of 3D materials, for example because they need to solely describe a shape (e.g., for many cases in additive manufacturing). In this example, photorealistic PBR materials are used to equip the 3D model with a realistic look. Without support for materials, the model will have to be rendered with a default material (often a default shade of gray).

Transparent Materials Support:

IFC: Partial support | IGES: No support

IFC Notes:

Transparency supported through material properties

Impact:

Transparency is commonly used for see-through objects, containing (usually partially) transparent surfaces. In this example, a transparent material is used to model the glass window of the microwave, so that one can see inside. Without support for this feature, the inside of the microwave cannot be seen, as the window will be rendered as an opaque surface.

Hierarchical Scene Graph Support:

IFC: Full support | IGES: Partial support

IGES Notes:

Basic entity relationships and grouping

Impact:

Scene graphs are one of the most common concepts in 3D computer graphics. By structuring the scene in a hierarchical way, logical parts of it can be easily addressed and transformed. This is useful in many applications, like games or 3D configurators. Without support for this feature, a 3D scene cannot be structured hierarchically, for example objects cannot be logically composed of smaller objects.

Scene Composition Support:

IFC: Full support | IGES: Partial support

IGES Notes:

Assembly relationships with limited constraints

Impact:

Scene Composition describes the process of composing a scene through links from a main scene that pull in various other scenes/3D models. This can also happen in a nested fashion (through multiple levels of linkage). With a target format not supporting this feature, references to external models must be resolved and the content be baked into one 3D model, which is then saved in that target format.

Standardized Format Support:

IFC: Full support | IGES: Partial support

IGES Notes:

Legacy format, superseded by STEP in 1994

Impact:

Standardization plays a huge role in 3D model formats. With a format being standardized, every application will have a clear way of how to load or store data using this format. This makes it easier to re-use the 3D model across different applications, but also to make sure it will still be accessible and usable after a couple of years.