Pros and Cons of 3D Printing File Formats

Consistent file formats will lead to clear communication which leads to good collaboration. There are four major file formats and we are going to detail the pros and cons of each. To cover the entirety of file formats is unrealistic, so below are the four most commonly used, “neutral” or “open- source” formats, meaning they are compatible across different software platforms. Here are the pros and cons of 3D printing file formats.

What is STL?

“STL stands for “stereolithography’ and is considered the granddaddy of all other 3D printer file formats. Developed in the late 1980s, it is one of the oldest file formats and is still widely used in today’s field of 3D modeling and printing.

The key characteristic of an STL file is that it simplifies a 3D surface as a “tessellation” – basically a series of small triangles. By increasing the number of triangles representing a surface, curved surfaces can be better approximated and recreated. However, using a large number of triangles can quickly bloat the file size of a model saved in the STL file format.

PROS…

Wide compatibility

The biggest advantage of saving and sharing files in the STL file format lies in the fact that it’s one of the oldest and simplest 3D file formats ever created. Thus, almost all 3D modeling software platforms and 3D printers have been designed to store or open STL files. Some modeling or slicer software even have “light” versions that are meant to open STL files exclusively. With such widely established ubiquity, the STL file format will likely continue to reign supreme for the foreseeable future.

Simplifies sharing and publishing

A 3D model saved as an STL file takes a lot of “shortcuts” to keep the file simple. Its curved surfaces are merely approximations, it does not contain any surface data and cannot retain any metadata. This simplicity makes STL files very easy to share and publish, as it trims out a lot of unnecessary bulk.

One other characteristic of STL files is that they are very difficult to edit. If there’s a section of an STL file that you need to revise, you’re better off modeling it from scratch rather than dealing with a stubborn STL file. While collaborators may see this as a drawback, publishers who release their 3D models for free use treat this limitation as their security from people editing their models and publishing it as their own.

CONS…

Only retains geometry data

An STL file contains data on the shape of the surface of a 3D model and nothing more. It does not carry any data on the color of each surface, its texture, or the material meant for printing the model. In fact, you can’t even embed any metadata on an STL file, making it hard to leave a trademark on a model that you’ve created.

Despite focusing solely on the geometry of the model, STL files are also massively known to be error-prone in how it approximates a surface. You may end up with overlapping triangles, or surfaces that are not entirely closed. These imperfections make it necessary to use an STL repair function before you can proceed to print an STL file – often a time-consuming step.

Limited level of detail

Since curved surfaces are only approximated in STL files, there is a limitation to the level of detail it can store and its fidelity to the source model. For now, STL files can get away with this limitation since most 3D printers also have limited resolution numbers, anyway. However, as 3D printers evolve and become more capable, it’s only a matter of time before the STL file format slowly becomes irrelevant.

What is OBJ?

Next to STL, the OBJ file format is the most commonly used in the 3D printing and modeling communities. Developed by Wavefront Technologies Inc., the OBJ file format is more commonly used in professional 3D modeling and is recognized by CAD software platforms and most game engines.

Heavily contrasting with STL, an OBJ file represents a 3D surface in a much more complex manner. Instead of tessellated triangles, a surface of an OBJ file is represented by a precise mesh which can comprise of various polygons, such as quadrilaterals or hexagons.

The ability of OBJ files to represent surfaces using a precise mesh encoding opens up the possibility of defining curved surfaces with non-discrete facets, such as splines. Aside from creating smoother surfaces, the use of splines allows a model to retain the same level of quality even when it gets scaled up.

An OBJ file can also contain a texture map as a separate, but associated file. A texture map wraps around the 3D object, thus acting as the file that defines its color or texture. This file can be saved as either a PNG file (texture map) or an MTL file (face attributes).

PROS…

Allows for collaboration

OBJ files retain a much higher level of fidelity, and this greatly facilitates collaborative work between different designers. A designer can create a model, share it as an OBJ file, and allow a different designer to make tweaks on it without losing any of its critical details. Because of its high level of precision, OBJ files are preferred by industries that rely on a very high level of precision, such as aerospace travel or automobiles.

Ideal for multicolor 3D printers

Basic 3D printers can really only print models using one filament at a time, making it unnecessary to use 3D models with texture maps or color data. If all 3D printers had this limitation, then this industry would not have any use of OBJ files.

However, it turns out that multicolor 3D printers are starting to become a thing. With OBJ files that can store texture or color data, a multi-extruder 3D printer will know when to shift from one filament to another. Admittedly, there aren’t a lot of 3D printers that have this kind of setup, but OBJ files are going to be much more common once multi-color 3D printing technology takes off.

CONS…

Limited compatibility

Despite the popularity of OBJ, we still have to accept the reality that its scope of compatibility is not quite as wide as STL. The tools you can use to edit or repair OBJ files are quite limited, and even popular software platforms need to have some sort of plugin installed before they can be used to open or export OBJ files. Before you start working with OBJ files, you need to make sure that your software and 3D printer is equipped to handle the file format.

Complex files

The complexity of OBJ files is beneficial in that it retains a large amount of surface and texture data at high fidelity. Unfortunately, this also means that sharing, publishing, editing, and repairing OBJ files can be really time-consuming processes. Considering that just finding the right tool or software for the job is already difficult, working with OBJ files when you’re ill-prepared can be a huge headache.”

This is only half of the file format breakdown, to get all the pros and cons of 3D printing file formats. Read the full article here.

Categories: Design & Process