Annotation types
Below you will find a table with all the annotation answer types that are currently supported on Grand Challenge. Details on the json and storage format be found in the Grand Challenge technical documentation.
| Answer type | Description | Stored as | Sidenote |
|---|---|---|---|
| Point | single point | 3D location of the point (json) | - |
| Multiple points | multiple points | array of points (json) | - |
| Distance measurement | single line drawn on a single plane | 3D locations of the start and end positions of the line (json) | - |
| Multiple distance measurements | multiple lines, each drawn on a single plane | array of lines (json) | - |
| 2D Bounding Box | rectangle drawn on a single plane | 3D locations of the four corners of the rectangle (json) | - |
| Multiple 2D Bounding Boxes | multiple rectangles, each drawn on a single plane | array of rectangles (json) | - |
| Line | line drawn on a single plane | array of 3D locations of the seed points of the line (json) | - |
| Multiple lines | multiple lines, each drawn on a single plane | array of lines (json) | - |
| Angle | two lines that do not need to intersect | two sets of two 3D locations marking the start and end point of the two lines | 1 |
| Multiple angles | multiple angles | array of angles (json) | 1 |
| Three-point angle | three points that form an angle | array of points (json) | - |
| Multiple three-point angle | multiple three point angles | array of 3-point angles(json) | - |
| Ellipse | two lines denoting the axis that describe the ellipse | 2 sets of 2 3D locations marking the start and end point of the two lines | - |
| Multiple ellipses | mulltiple sets of lines | array of ellipses | - |
| Polygon | shape drawn on a single plane | array of 3D locations of the seed points of the polygon (json) | 2 |
| Multiple polygons | multiple shapes, each drawn on a single plane | array of polygons (json) | 2 |
| Mask | multiple shapes, each drawn on a single plane | mha file | 3 |
Sidenotes:¶
1). For calculating the angle between two lines that intersect, the angle is calculated on the closest point on the intersected line. This results in an apparent "jumping" of the calculated angle (see video), but this is merely the result of the change in the reference point. The location of the dashed line and the label shows which angle is calculated.
Use the three-point angle answer type to enforce that the two lines meet.
2). For (Multiple) polygons answer types, it is possible to create a large (number of) polygon(s) for a single question. This can lead to issues when saving these answers to Grand Challenge, as the answer becomes very large. You should consider using the Mask answer type if you expect a high number of polygons. With the option to switch between editors, you can utilize the polygon tool options and the mask tool options.
Use Mask answer type if you expect a high number of annotations for a single question or you if prefer your answer in image format
Use Polygon or Multiple polygons answer type if you don't expect a high number of annotations for a single question and you prefer the answers in a json format
3) Masks are not supported for multi-resolution images and 4D images. To create a multi-category mask answer in a Reader Study, you need to define two additional settings, the overlay segments, which specify the different categories in your mask, and the lookup table, which defines the color and alpha of the various categories.
You can set the overlay segment and look up table directly in the question (go to your reader study -> Questions -> Edit question). It is also possible to set the overlay segment and look up table in the interface of the default answer if you provide a default answer.
Requirements:
- The question needs to be of type Mask
- The interface (in case of default answers) needs to be of kind Segmentation
- The overlay segments and look-up table will be sourced from the following, if available:
- as defined in the interface of a default answer
- as defined in the question
- as defined in the Viewer configuration
- as defined in the internal look-up table of the Viewer.