How to convert CATIA V6 (3D XML)
to X3D?

3DXML is an open-standard proprietary 3D file format developed and supported by Dassault Systemes. 3DXML files are typically created as exports from Dassault Systemes' 3DEXPERIENCE application. The 3DXML file is a zip archive file consisting of a BOM file and one or more 3D representations stored in either XML or binary format. Compact file size allows users to transfer 3D XML quickly and embed it into websites, emails, and various MS Office documents. Therefore, the format is commonly used to integrate 3D data into technical documentation.

X3D is ISO standard XML-based file format for representing 3D computer graphics. X3D features extensions to VRML (e.g. CAD, geospatial, humanoid animation, NURBS etc.), the ability to encode the scene using an XML syntax as well as the Open Inventor-like syntax of VRML97, or binary formatting, and enhanced application programming interfaces (APIs).

The X3D extension supports multi-stage and multi-texture rendering; it also supports shading with lightmap and normalmap. Starting in 2010, X3D has supported deferred rendering architecture. Now X3D can import SSAO, CSM and Realtime Environment Reflection/Lighting. The user can also use optimizations including BSP/QuadTree/OctTree or culling in the X3D scene.