The Complete DGN to OBJ Conversion Guide

Free-Form Surfaces Support:

DGN: Full support | OBJ: No support

Impact:

Free-form surfaces allow a CAD user to design surfaces with advanced controls over curvature and continuitiy. While these surfaces are common for CAD models (in the form of so-called boundary representations or "B-reps"), they need to be converted to polygonal triangle or quad data to work with most 3D rendering engines - a process called tessellation. In this example, a surface patch is used to describe a part of a curved surface of a product. Without support for this feature, the free-form surface has to be tessellated into quads or triangles.

Texture Transforms Support:

DGN: Full support | OBJ: No support

Impact:

Texture transforms describe transformation operations that are applied to 2D texture images or UV coordinates when using 2D texture data on a 3D surface. They can be used, for example, to make sure that material patterns are using real-world scale when rendered on the 3D surface. In this example, such a pattern is used and scaled with the help of a texture transform. Without support for this feature, the texture pattern shows up at the wrong scale.

Multiple UV Channels Support:

DGN: Partial support | OBJ: No support

DGN Notes:

Limited multi-texturing capabilities

Impact:

Multiple UV channels allow the optimized and sophisticated use of various 3D modeling features at once. For example, one can use one set of UVs and 2D texture data to model a tiling texture or procedural material, and another UV set to leverage a global lightmap or occlusion map of the 3D model. In this example, a combination of tiled texture (UV channel 1) and baked ambient occlusion map (UV channel 2) is used. Without support for this feature, one needs to either give up the tiling property (e.g., by using a tool like RapidPipline to bake a single texture atlas), or give up the ambient occlusion map, as only one UV channel will be usable.

Embedded Textures Support:

DGN: Partial support | OBJ: No support

DGN Notes:

Textures can be referenced or embedded

Impact:

Embedded textures allow the storage and exchange of an entire 3D model and its materials within a single file, by embedding the texture images directly into the 3D file (and not storing them as separate image files). Without support for this feature, textures have to be stored in separate image files, and referenced from the main 3D model file.

Vertex Colors Support:

DGN: Full support | OBJ: No support

Impact:

Vertex colors allow the attachment of colors to each vertex of a 3D model. This can be useful in scenarios such as scientific visualization, or when converting/meshing data from a colored 3D point cloud, for example. On the polygonal surface connecting the vertices, the respective vertex colors are usually smoothly interpolated. In this example, different colors are attached to the different corners of a cube. Without support for this feature, the cube won't have any colors.

Animations Support:

DGN: Partial support | OBJ: No support

DGN Notes:

Simple animation support for design sequences

Impact:

Animations are an important part of many interactive 3D assets, for example in real-time rendering (including games, XR training, assembly instructions, product demos, and other use cases). There are various kinds of animations that can be used on 3D models. In this example model, a rigid animation is used to make the gears spin. Without support for this feature, in this example, the gears won't move.

Rigid Animations Support:

DGN: Partial support | OBJ: No support

DGN Notes:

Basic animation for construction sequencing

Impact:

Rigid Animations are typically used to animate mechanical parts. In this example, the door of this 3D model of a microwave can be interactively opened or closed, using a rigid animation that gradually changes the 3D transformation of the door. Without support for this feature, in this example, the door will just stay in place and won't move.

Hierarchical Scene Graph Support:

DGN: Full support | OBJ: No support

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:

DGN: Full support | OBJ: No support

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.