3D and rich media need alternative descriptions

PDF/UA check MULTIMEDIA_ALT_DESCRIPTION · Annotations · severity Critical · PDF/UA 8.9.2.4.18 / 8.9.2.4.19 3D and RichMedia

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Why it matters#

Interactive 3D models and rich media are entirely visual. Without alternative descriptions, they are completely inaccessible to blind users.

What you will see#

A 3D model or rich media annotation has no alternative description.

How to fix#

Add a Contents entry to the 3D or RichMedia annotation dictionary describing what the model or media shows and what interaction it offers (e.g. 'Interactive 3D model of the engine assembly; rotate to view components').

Step-by-step guide#

1. Locate each flagged 3D or RichMedia annotation from the report's page numbers and previews.
2. Compose a Contents description stating what the model or media shows and what interaction it offers, e.g. Interactive 3D model of the engine assembly; rotate to view components.
3. Add the description in the authoring application before export - Acrobat Pro's 3D and rich media placement tools provide no field that writes this entry (8.9.2.4.19), so a file already missing it must be regenerated from source with the description in place.
4. Make the text meaningful: empty or whitespace-only Contents fails, and a bare file name does not convey the media's purpose.
5. If the directly enclosing structure element has an Alt entry, make it identical to Contents (8.9.4.2), and for RichMedia audio or video also supply media clip CT and Alt entries (MEDIA_CLIP_CT, MEDIA_CLIP_ALT).

Verify: Re-run the EQChecker scan; MULTIMEDIA_ALT_DESCRIPTION should pass.

Note: PDF/UA-2 only covers the alternate description; per the 8.9.2.4.19 NOTE, additional requirements such as WCAG (captions, transcripts, keyboard-operable players) apply on top when 3D, video or audio is included. This check runs under PDF/UA-2 only.

WCAG success criteria#

1.1.1 Non-text Content — Level A#

All non-text content (images, icons, controls) needs a text alternative that conveys the same purpose, or be marked decorative so assistive tech can ignore it.

Understanding 1.1.1

Standards#

This check contributes to the following standards:

PDF/UA WCAG A EN 301 549