# Topological Information

The blob scene description provides access to a tree structure that describes the label and topological relationship of each feature in the scene.

The following topological information is available about the blob scene as a whole:

- The number and IDs of all top-level features, which are those features that are not enclosed by any other feature in the scene
- The total number of features within the scene

For each feature in the scene the following topological information is available:

- The label of this feature. In the case of grey-scale connectivity, the label is 0 for holes and 1 for blobs. In the case of labeled connectivity, the label is the feature's label.
- The number and IDs of this feature's child features, which are those features completely and directly enclosed within this feature
- The ID of this feature's parent feature, which is the feature that directly encloses this feature
- The number and IDs of this feature's sibling features, which are any other features which are directly and completely enclosed within the same feature that directly encloses this feature