Element

An Element is the base unit to describe any type of document. At its core, it only has a name, and a type; other fields are optional.

Structure🔗

To represent a document in Arkindex, we'll need to:

1. Apply a Type to each element. Types are managed at projects level, and can be thought of as categories for elements,
2. Link elements together, so we can build a complex hierarchy that will represent your document: this is where we'll use the Path,
3. Link images to some elements; each Element can use a part of an Image by specifying the image and polygon to use.

Types🔗

For example, a project with historical books could have the following simple structure:

In this example, we have 4 different Element types:

• Volume is a folder, that will be used to group several elements of type Page
• Page represents a single page of a Volume. These elements will be directly linked to a full image provided by the client.
• Paragraph will be created either by a human annotator, or by a Machine Learning tool.
• Line will generally be generated by a Machine Learning tool. In this case it could either be directly linked to a Page and/or a Paragraph.

Arkindex does not assume any structure for a Project's types, the Project administrator is free to create as many types as needed. To know more about Element types, please read the next page dedicated to Types.

Hierarchy🔗

The hierarchy between elements is not enforced at the Type level (there is no graph between different types), but at the Element level.

A user can create any hierarchy between Elements using multiple Paths. A Path is simply a link between elements, linking a Parent element with Children elements. Using the example above, we can see that different instances of Page are all linked to a single Volume.

We would then have two paths to represent that hierarchy:

1. From Page 1 to Volume 1
2. From Page 2 to Volume 1

To know more about Element paths, please read the page dedicated to Paths.

Associate to an image🔗

An Element may have a link towards an Image, but this is not mandatory. Some elements are purely present for organisation purposes (like a folder on a file system).

In the example above, different elements would be linked to parts of images:

• Page elements would be linked to full size images directly provided by the client,
• Paragraph elements would be linked to a large portion of an image,
• Line elements would be linked to a thinner portion of an image.

Elements can be linked to images with a polygon. A polygon lists three or more points that specify which part of the image is represented by an element.

API Endpoints🔗

These endpoints are the most useful to handle Element:

• CreateElement
• CreateElementParent
• ListElements
• RetrieveElement
• DestroyElement