How does it work?
Converting from the 3MF file format to OBJ can be a complex process and any tool used for this conversion process needs to be able to handle a variety of data conversion tasks as well as identify any defects within the 3D model and fix them. Here we will explain the conversion process used by our tool to accurately convert your 3MF file to a valid OBJ 3D model suitable for 3D printing. Lets start with the conversion process, which involves the following steps:
Step 1: Read the Source 3MF File
A 3MF file is a collection of 3D model data files including mesh and texture data compressed into a single file aimed at the 3D printing arena. The file is basically a ZIP file containing the relevant 3D files with the 3MF extension. The internal mesh structure is stored within various XML files making this easy to read in using a standard XML parser.
Our tool can read the compressed 3MF file and parse the 3D model contents taking into account all vertex, face and material information. As the 3MF format supports nested models within the 3D scene our tool will check for these and perform any world space transforms that are needed.
When our tool reads this 3D data, all we are interested in are the vertices, faces, normals, materials, and textures, as this is the only data that can be accurately converted into the final OBJ file.
The 3MF file can contain data such as material definitions and textures that describe how a particular set of 3D geometry should be rendered. As we are creating an OBJ file, which supports both materials and textures, our tool will attempt to load any materials and textures present in the 3MF file.
For more information regarding the 3MF file format, please see this great article that goes into a lot of detail explaining the 3MF format.
Step 2: Process File Data
With the 3MF file data read, our tool generates an internal representation of the full 3D model and will attempt to fix any geometry issues encountered. Along with repairing any issues with the 3D model, the tool will remove any duplicated vertices and prepare the model for exporting to the OBJ format.
Step 3: Saving to the OBJ Format
The OBJ format has been around for many years and has become a standard format for 3D modeling. Most 3D modeling software can open OBJ files, which means our tool now needs to take the in-memory 3D model we created in step 2 and convert it to the OBJ format, ensuring it can be opened in all 3D modeling software with no compatibility issues.
Along with the completed OBJ file, a separate MTL file will also be created, along with any textures that were present in the original 3MF file. Depending on the original texture format, these textures will be saved in either PNG or JPG format. If the original format was neither of these, for example, if your model contained a texture in the TIF format, it will be converted to a PNG.
