Recherche multimodale

A text query might retrieve an image, or an image might find related documents. The modalities must be represented in compatible ways, and similarity still needs evaluation against the user’s task.

Points clés à retenir

• Define the required evidence by modality.
• Use compatible representations.
• Preserve provenance and permissions across derived assets.

Choose what each query and result should mean. Searching for a visually similar product is different from finding a video containing a spoken phrase. A model trained to align captions and images may not support every audio or temporal task. Preserve metadata and original assets. Source, time range, permissions, and descriptive text can help ranking and verification. An embedding alone may lose exact identifiers, negation, or details that matter to the query. Combine signals where appropriate. Keyword matching can support exact names, while learned representations support semantic or visual relationships. Evaluate the fusion and ranking on realistic examples instead of assuming that adding modalities always improves relevance. Test difficult distinctions: similar-looking but different objects, images with important text, videos whose appearance matches but audio does not, and queries involving absence or spatial relationships. Keep access controls consistent across derived embeddings, thumbnails, transcripts, and original files.

1. Use the invented query “a dog barking” against a video collection.
2. A visual matcher may return a silent clip showing a dog. Confirm whether the task requires the sound, the visible action, or either.
3. Evaluate results using the required evidence instead of accepting a broadly related image match.

The constructed example separates topical similarity from satisfying a multimodal query.