> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cognite.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Contextualize CAD models in asset-centric and hybrid projects

> Review CAD node metadata through the 3D nodes endpoints and contextualize by linking CAD nodes to assets using 3D asset mappings.

## Contextualize

In **asset-centric (legacy)** and **hybrid** projects, CAD node metadata is extracted during CAD processing and stored in the 3D database. You can review this metadata through the 3D nodes endpoints and then contextualize by creating 3D asset mappings that connect CAD nodes to assets.

<Steps>
  <Step title="Review CAD node metadata">
    CAD node metadata is produced implicitly during CAD processing. The optimizer extracts node metadata from the CAD file and stores it in the 3D database, where it is exposed through the 3D nodes endpoints.

    Use the 3D nodes endpoints to list and filter nodes for the CAD revision you want to contextualize:

    * [Filter 3D nodes](https://api-docs.cognite.com/20230101-beta/tag/3D-Model-Revisions/operation/filter3DNodes)
    * [List 3D nodes](https://api-docs.cognite.com/20230101-beta/tag/3D-Model-Revisions/operation/get3DNodes)
  </Step>

  <Step title="Create contextualization approvals">
    To approve contextualization, create 3D asset mappings with the [Create 3D asset mappings](https://docs.cognite.com/20230101/3d-asset-mapping/create-3d-asset-mappings) API endpoint.

    In **hybrid** projects, map a CAD node to a data modeling service (DMS) instance by using `nodeId` and `assetInstanceId`.
  </Step>
</Steps>