Recommendation: Use NSDT editor to quickly build programmable 3D scenes
Integrating static and animated 3D content into mobile augmented reality (AR) experiences is an effective way to enhance user immersion and engagement. However, creating 3D objects for AR can be quite daunting, especially for those with little experience in 3D modeling. Unlike adding video or photo AR layers, generating 3D objects requires technical expertise and specialized software.
However, we'd love to help - this tutorial aims to guide you through creating 3D content for mobile augmented reality using the free and open source 3D creation software Blender. The following article provides a detailed step-by-step procedure on how to use Blender to generate 3D objects that can be seamlessly integrated into a 3D editor.
If you already have a usable 3D model and just need to convert it to a format supported by the 3D editor, you can use 3DConvert, an online 3D format conversion tool .
1. Why is Blender a great choice for Augmented Reality?
With its powerful suite of 3D modeling tools and open-source availability, Blender is an excellent choice for developers and designers looking to create mobile augmented reality content without breaking the bank. Blender offers a range of features that rival expensive 3D modeling software such as Cinema 4D, 3DS Max, and Maya. Unless you've already invested in paid software, there's no significant advantage to choosing a more expensive alternative to Blender.
Over the past few years, Blender has made remarkable strides in expanding its capabilities and features. It is now widely recognized as the industry standard tool for creating 3D content. With its user-friendly interface and comprehensive feature set, Blender has become a popular choice for both novices and experts looking to use it for AR.
2. Prepare the 3D object for use in the 3D editor
In order to ensure that your 3D objects are compatible with the 3D editor, it is important to prepare them properly. If your objects don't have any motion or animation, you can import them in OBJ format.
However, if you have more complex animation scenes, you will need to export them in glTF or FBX format. The glTF format is particularly suitable for web and mobile applications because it is optimized for fast loading and rendering.
To create a 3D object for a 3D editor, you need to export a 3D model and animation from Blender, then upload this 3D object to the 3D editor, which has built-in file optimization tools.
3. Understand the structure of 3D models: polygons and meshes
The initial phase of 3D development is modeling, where objects are actually created in three dimensions. Blender offers several modeling techniques, of which "mesh modeling" is the most widely used and basic method.
What is a grid?
In 3D modeling, a mesh is a set of vertices, edges, and faces that define the shape of an object.
A vertex, also known as a point, is a single location in space:
Edges are straight lines connecting two vertices, defining the line segment between them:
A face, also known as a polygon, is a flat surface surrounded by edges. It is defined by three or more vertices connected by edges.
What is a polygon?
A polygon is a geometric shape formed by connecting three or more vertices with straight edges in three-dimensional space. Vertices, edges and faces are the basic components of a polygon, where a face refers to the interior area of a polygon. Polygonal modeling usually involves using three-sided shapes called triangles or four-sided shapes called quadrilaterals.
A polygonal face is defined by an area enclosed by three or more vertices and their associated edges. Many connected faces create a polygon mesh, also known as a polygon set or polygon object, used to create 3D polygonal models.
When creating augmented reality models and scenes in Blender, there is no specific requirement for the number of polygons required. However, it's important to remember that people may be accessing this content on a variety of devices, some of which may be older. To ensure the best performance, it is best to keep the polygon count low.
While modern devices can easily handle 600,000 to 1 million polygons, it is recommended to limit scenes for mobile devices to 250,000 polygons.
3. Prepare animation
Object animation can be created in a number of ways, including object transformations, which involve changing an object's position, size, and rotation along the x, y, and z axes. Object rigging is another way to animate complex objects such as humans, animals, and mechanical devices with multiple parts.
For example, a recent project utilized a rigging system to simulate the movement of butterfly wings.
To create animation, you mark keyframes in the timeline to indicate where the object's bones or armature change positions in x, y, and z space.
The timeline is the main tool used to create animations, and animation titles and their associations with specific objects are added in the Dope Sheet tab, which can be accessed through the Motion Editor view.
5. Understand the color and light differences between rendered visualizations and AR
Adding color to objects in Blender is a simple task. You can choose a material and assign it a color. However, if you wish to incorporate other visual elements such as textures, symbols, or color variations, you will need to create materials.
Blender provides an option to create and bake textures onto objects in the form of .JPG or .PNG. When creating textures, it is very important to ensure that the lightning and shadows in the scene are not baked, as they will conflict with the Unity project lights. Therefore, it is recommended to select the bake type as Diffuse and only turn on the Color option.
Before baking a texture, it is necessary to check that the normals are facing the correct direction. If not, some polygons will appear black or transparent in the 3D editor environment. Reversing the normals can fix this. Once a texture is baked, it can be assigned to a specific object and a new material can be created with the attached texture.
Keep in mind that when viewing 3D models on platforms such as Sketchfab, Blender or Unity 3D, the appearance may vary due to differences in rendering systems. These systems handle elements such as lighting, textures, and shadows in unique ways, resulting in slightly different final appearances of the model.
However, by utilizing the glTF or GLB formats and Universal Material Layer (UML) materials, you can standardize the appearance of your models, ensuring more consistent visual output across different platforms.
6. UV Mapping Guide
Before texturing a model in 3D modeling, it is critical to create a UV coordinate system map. As daunting as this sounds, it's a simple process. In short, it's a 2D image that shows where texture occurs on a 3D object. It's like creating a paper layout for a cube, then cutting, folding and gluing. Once the layout is created, textures can be designed for each object and imported into the 3D editor.
In addition to the previously mentioned methods, programs such as Photoshop can also be used to create textures. Various textures can be used to make a material shiny, transparent, rough, or similar. Each texture should be saved as a .JPG file. This is useful, for example, to create reflections in windows or to highlight different aspects of a building's facade.
In Blender, there is no need to create lights or cameras, as prepared files can be imported directly into the 3D editor.
7. Understand the advantages of file formats and glTF
After creating an animation, it must be exported in glTF (.gltf/.glb), FBX or OBJ format. These file types allow saving objects, textures, animations and skeletons.
The glTF file format is gaining popularity in the industry. Its design emphasizes compact file size, fast loading, runtime independence, and full 3D scene representation.
Before glTF, the two main formats for transferring 3D model data between authoring tools and engines were FBX and OBJ. FBX has many outdated features, and its proprietary nature and large C++ SDK prevent direct loading in web browsers. For the OBJ format, it has limited capabilities and is inefficient in terms of storage space and read/write speed.
Some industry experts expect the use of glTF to continue to grow, potentially making it the standard format for asset exchange within the industry. Given Blender's potential for augmented reality, it could play an important role in achieving this result.
Finally, when exporting, it is important to include only the mesh and skeleton. Best practice is to provide texture maps to the 3D editor at the same time as submitting the file to ensure a smooth integration.
8. Export 3D models from Blender in glTF format
To export a 3D model from Blender in glTF format, follow these steps:
- Open your 3D model in Blender.
- Make sure the model is set up correctly, including materials, textures and UV maps.
- Click on "File" in the upper left corner of the Blender interface and select "Export" from the drop-down menu.
- Select "glTF 2.0 (.glb/.gltf)" from the export format list.
- In the Export Options panel on the right, select "GLB" (binary format) or "GLTF" (text format) as your preferred format. GLB files are more compact, while GLTF files are easier for humans to read.
- If necessary, configure other export settings, such as applying modifiers, selecting objects to export, or adjusting animation settings.
- Choose a destination folder for the exported files and give it a name.
- Click Export to save the file in the format of your choice.
9. Troubleshooting Guide
When you're working with 3D content in Blender, you can run into issues like broken texture appearances, but these are usually due to human errors that are easy to fix. Here are some of the most common scenarios:
- Check for errors: Reimport the exported glTF file into Blender to see if it is displayed correctly. If not, check the Blender console for any error messages, as they may provide useful information about the problem.
- Validate Materials and Textures: Make sure materials and textures are correctly applied to your model in Blender. Missing or improperly assigned textures can result in a corrupted appearance. Also, make sure you use a supported material type for glTF export.
- Check UV Mapping: Carefully check your model's UV mapping to ensure that textures are correctly mapped to geometry. Incorrect UV maps can cause distorted or misplaced textures on exported models.
- Apply Transforms: Before exporting, apply any transforms (scale, rotation, position) to the model by selecting the object, pressing Ctrl+A, and choosing All Transforms.
- Apply modifiers: If your model has any modifiers (such as subdivision surfaces or booleans), apply them before exporting to ensure the correct geometry is included in the exported file.
- It is also good practice to double check the export settings.
10. Taking mobile augmented reality to the next level
As this guide proves, Blender is a powerful 3D modeling and animation software that offers numerous advantages for creating mobile augmented reality projects.
Its versatility enables developers to create complex 3D models and animations and export them to 3D editors. The software's compatibility with the glTF file format ensures efficient compression of models and animations for mobile devices while maintaining their high quality.
With a large collection of plugins and add-ons for AR-specific content, Blender is the first choice for augmented reality developers eager to create immersive and best-in-class AR experiences for mobile devices.
Original Link: Blender Augmented Reality Model Making—BimAnt