The Complete OBJ to PLY Conversion Guide

General Information

This guide is part of the RapidPipeline 3D Formats Knowledge Database. It shows how to convert OBJ to PLY, if you'd like to know more about the formats, please check out the following links:

• Learn more about the OBJ format
• Learn more about the PLY format
• Limitations of a OBJ Files to PLY Conversion Workflow

What are OBJ and PLY files commonly used for?

The OBJ file is a format mostly used for 3D modeling and generalized 3D applications.
The PLY file is a format mostly used for 3D scanning.

Limitations of a OBJ Files to PLY Conversion Workflow

The following limitations should be taken into account when converting OBJ files to PLY format:

OBJ Feature (not supported by PLY)	Limitation Details
Texturing	Texturing: supported in OBJ, but not in PLY. 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.
Normal Mapping	Normal Mapping: supported in OBJ, but not in PLY. Normal maps are used to model shading differences that are arising from small geometric details on a surface, such as fabric structures, visible gaps between bricks forming a wall, or rough rock surfaces. In this example, a normal map is used to model a fabric structure. Without support for this feature, the rendered fabric will look smoother than it actually is in the real world, as the fabric structure won't be visible.
Materials	Materials: supported in OBJ, but not in PLY. 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	Transparent Materials: supported in OBJ, but not in PLY. 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.
PBR Materials	PBR Materials: supported in OBJ, but not in PLY. PBR materials enable Physically-Based-Rendering (PBR) for a standardized, photorealistic look of rendered images. PBR uses concepts like metallic-roughness or specular-glossiness properties and a microfacet-based modeling of the surface, using a concept called BRDF (Bi-Directional Reflectance Distribution Function). In this example, PBR materials are used to achieve realistic looking plastic and metal materials. Without support for PBR materials, only basic colors and shading can be used (for example, based on more simple shading models, such as the Blinn/Phong model).
Scene Nodes	Scene Nodes: supported in OBJ, but not in PLY. Scene nodes make it possible to address parts of a 3D model separately. For example, a part could be dynamically hidden or shown as part of a 3D configurator. Without support for this feature, a 3D scene will only consist of a flat model, without parts being individually configurable.
Standardized Format	Standardized Format: supported in OBJ, but not in PLY. 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.

Converting and Optimizing OBJ Files to PLY

There are various ways to convert between OBJ and PLY. With RapidPipeline, you can easily convert and and optimize OBJ files, at scale. It supports PLY, as well as many other file formats (examples: 3dsMax, FBX, glTF, STEP, STL, USD, USDZ, VRM), at high quality.

Due to the potential limitations aforementioned on the table above, in principle, one cannot always perfectly convert 3D data between PLY and other formats. In the following, you can find conversion guides between PLY and the most important other formats, along with a rough score for compatibility of this workflow:

What's the best way to get OBJ files into my 3D applications, and are there alternatives to using PLY?

Doing 3D conversion right, especially at scale, can be tricky, as 3D data is in general a rather complex (yet very powerful!) medium. This also applies to OBJ and PLY files - the conversion guide above provides a rough first idea about that. Once you know what you would like to do, tools like RapidPipeline can help you perform the necessary steps, and to even automate the process for thousands or even millions of files.

Especially when introducing pipelines and workflows at scale in an enterprise context, it is usually good to rely on dedicated tools and expertise, making sure you do not introduce any steps into your 3D workflow that are detrimental to the final output's quality, or that take your team too much time (and money).

If you're interested to hire dedicated expertise from the best in the field to help your company reach your goals fast and reliably, please do not hestitate to contact DGG. Being the creators of RapidPipeline, and ambassadors for open 3D standards for more than a decade, we have been building some of the world's most advanced 3D pipelines, having processed many millions of 3D assets.

Therefore, our expertise will help you to reach your goals faster, at scale, and with the least possible friction, since we are focused on maximum interoperability.

To get started with 3D data conversion and optimization today, sign up for a free account!

If you have any questions, feel free to chat with our human team.