For 12.x and later products, the Oct. 13, 2015 release changes the default product behavior because the dynamic nature of 3D provides the potential for it to be subject to security vulnerabilities. Several changes have been implemented:

• 3D is disabled by default.
• The user interface has a new checkbox at Preferences > 3D and Multimedia > Enable 3D Content.
• 3D content has been integrated into the Trust Framework so that it's possible to display 3D content for trusted content even when 3D is disabled. You can trust files, folders, and hosts as privileged locations via Preferences > Security (Enhanced) > Privileged Locations panel so that when a PDF with 3D content opens:
• If it is trusted, the 3D content renders.
• If it is not trusted, a Yellow Message Bar appears which states that the file might pose pose a security risk. The Options button provides options for trusting once or always.
• Trusting the document for always adds the file to the privileged locations list and sets a registry entry under \TrustManager\cTrustedFolders\cTrustedFor3D.

Summary table

b3DEnableContent	Specifies whether to trust and render 3D content.
bEnable3D	Specifies whether to trust and render 3D content.