Materials define rendering methods of an object. Mesh indicates the geometric information of 3D objects, and Buffer, buffer view, and accessors indicate information related to references and layouts. Scene and Nodes are the basic structures of Scene, and Camera is an element that sets the time point of a scene.
Figure 2 shows the concept of glTF Asset and related top-level elements. One basic element of glTF is JSON file which specifies the structure or formation of a scene that includes 3D models. The format called glTF was designed specifically for Khronos Group in order to secure efficiency transmission of 3D contents between networks. Importer and Converter of OBJ, FBX, and STL 2.2 glTF Structure The process of conversion by means of the Importer and Converter may cause a time cost to the user.įigure 1. 3D model data shall be converted by means of the corresponding Importer and Converter depending on the Runtime applications.
It is impossible to apply files directly to Graphic APIs such as WebGL immediately after such files are created by an authoring software tool such as Blender and Maya. Figure 1 shows the process steps of existing 3D file formats. STL may be read with binary or ASCII codes in a disc, but no information on model colors is saved. STL is one of the international standard formats that represent 3-D data, and it is used commonly in an input file for most 3D printers. It may be expressed in a binary format disc or ASCII data. FBX was developed by Kaydara, Autodesk has the exclusive ownership. Since it uses a separate material file entitled MTL, MTL files that specify the texture map and material data need to be transferred as well in addition to model information. Data may be saved in an ASCII form (extension: obj) such as DXF and IGES or in a binary format (extension: mod). Background Theory 2.1 OBJ, FBX, STL Importer and Converter StructuresĪmong OBJ, FBX, and STL which are major 3D file formats, OBJ was developed by Wavefront Technologies specifically for Visualizer. Additionally, the rending efficiency of each 3D file format in a web application is analyzed based on the loading time. This study presents details of glTF which is a multi-functional, light-weight 3D file format in comparison of its attributes with those of other 3D file formats being currently used such as OBJ, FBX, and STL. In addition, glTF can save large-size elements such as geometry in a binary format and refers to such binary files through JSON, making the rendering process faster. Among these, glTF features the multi-function support and light-weight in order for standardization of 3D file formats.
Since such 3D file formats were developed for different purposes, their sizes and attributes are different from one another. Major 3D modeling file formats include OBJ, FBX, STL, glTF. This study is expected to contribute to reducing rendering time on the web as 3D file formats are used. As to STL, relatively excessive traffic was observed. Experimental results show that glTF is the most efficient and that it exhibits the best performance. The loading time and packets of each 3D file format are measured according to the web browser environment by means of Google Chrome, Firefox and Microsoft Edge. It also explains the concept and characteristics of glTF and compares its performance with other 3D file formats on the web. This paper presents explanation on OBJ, FBX, and STL which are major examples of existing 3D file formats. glTF helps uniform integration of 3D file formats and allows for more efficient transmission of large 3D geometry files by organizing them in a binary format.
Each format has limitations depending on its configuration and usage, and supported formats are different depending on the software application. 3D file formats typically include OBJ (Wavefront file format), STL (STereoLithography), and FBX (Filmbox).