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# fiftyone.utils.labels

Label utilities.

Copyright 2017-2026, Voxel51, Inc.
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[voxel51.com](https://voxel51.com/)
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**Functions:**

| [`objects_to_segmentations`](#fiftyone.utils.labels.objects_to_segmentations)(sample_collection, ...)    | Converts the instance segmentations or polylines in the specified field of the collection into semantic segmentation masks.                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [`export_segmentations`](#fiftyone.utils.labels.export_segmentations)(sample_collection, ...)            | Exports the semantic segmentations, instance segmentations, or heatmaps stored as in-database arrays in the specified field to images on disk.                                                                                                                                                                                                                     |
| [`import_segmentations`](#fiftyone.utils.labels.import_segmentations)(sample_collection, in_field)       | Imports the semantic segmentations, instance segmentations, or heatmaps stored on disk in the specified field to in-database arrays.                                                                                                                                                                                                                               |
| [`transform_segmentations`](#fiftyone.utils.labels.transform_segmentations)(sample_collection, ...)      | Transforms the segmentations in the given field according to the provided targets map.                                                                                                                                                                                                                                                                             |
| [`segmentations_to_detections`](#fiftyone.utils.labels.segmentations_to_detections)(...[, ...])          | Converts the semantic segmentations masks in the specified field of the collection into [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) with instance masks populated.                                                                                                                                                |
| [`binarize_instances`](#fiftyone.utils.labels.binarize_instances)(sample_collection, in_field)           | Binarizes the instance segmentations in the specified field according to the provided threshold.                                                                                                                                                                                                                                                                   |
| [`instances_to_polylines`](#fiftyone.utils.labels.instances_to_polylines)(sample_collection, ...)        | Converts the instance segmentations in the specified field of the collection into [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) instances.                                                                                                                                                                            |
| [`segmentations_to_polylines`](#fiftyone.utils.labels.segmentations_to_polylines)(...[, ...])            | Converts the semantic segmentations masks in the specified field of the collection into [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) instances.                                                                                                                                                                      |
| [`classification_to_detections`](#fiftyone.utils.labels.classification_to_detections)(...[, progress])   | Converts the [`fiftyone.core.labels.Classification`](fiftyone.core.labels.md#fiftyone.core.labels.Classification) field of the collection into a [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field containing a single detection whose bounding box spans the entire image.                                       |
| [`classifications_to_detections`](#fiftyone.utils.labels.classifications_to_detections)(...[, progress]) | Converts the [`fiftyone.core.labels.Classifications`](fiftyone.core.labels.md#fiftyone.core.labels.Classifications) field of the collection into a [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field containing detections whose bounding boxes span the entire image with one detection for each classification. |
| [`index_to_instance`](#fiftyone.utils.labels.index_to_instance)(sample_collection, label_field)          | Populates [`fiftyone.core.labels.Instance`](fiftyone.core.labels.md#fiftyone.core.labels.Instance) values in the <br/><br/>```<br/>``<br/>```<br/><br/>instance\`\`attribute of the specified label field based on the values in the specified index attribute.                                                                                                    |
| [`perform_nms`](#fiftyone.utils.labels.perform_nms)(sample_collection, in_field[, ...])                  | Performs non-maximum suppression (NMS) on the specified [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field.                                                                                                                                                                                                        |
| [`detections_3d_to_cuboids_2d`](#fiftyone.utils.labels.detections_3d_to_cuboids_2d)(...[, progress])     | High-level orchestration of 3D → 2D label conversion.                                                                                                                                                                                                                                                                                                              |

### fiftyone.utils.labels.objects_to_segmentations(sample_collection, in_field, out_field, mask_size=None, mask_targets=None, thickness=1, output_dir=None, rel_dir=None, overwrite=False, save_mask_targets=False, progress=None)

Converts the instance segmentations or polylines in the specified field
of the collection into semantic segmentation masks.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the objects field for which to render
    segmentation masks. Supported types are
    [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection),
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections),
    [`fiftyone.core.labels.Polyline`](fiftyone.core.labels.md#fiftyone.core.labels.Polyline), and
    [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines)
  * **out_field** – the name of the [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation)
    field to populate
  * **mask_size** (*None*) – the `(width, height)` at which to render the
    segmentation masks. If not provided, masks will be rendered to
    match the resolution of each input image
  * **mask_targets** (*None*) – a dict mapping pixel values (2D masks) or RGB hex
    strings (3D masks) to label strings defining which object classes
    to render and which pixel values to use for each class. If omitted,
    all objects are rendered with pixel value 255
  * **thickness** (*1*) – the thickness, in pixels, at which to render
    (non-filled) polylines
  * **output_dir** (*None*) – an optional output directory in which to write the
    segmentation images. If none is provided, the segmentations are
    stored in the database
  * **rel_dir** (*None*) – an optional relative directory to strip from each input
    filepath to generate a unique identifier that is joined with
    `output_dir` to generate an output path for each segmentation
    image. This argument allows for populating nested subdirectories in
    `output_dir` that match the shape of the input paths. The path is
    converted to an absolute path (if necessary) via
    [`fiftyone.core.storage.normalize_path()`](fiftyone.core.storage.md#fiftyone.core.storage.normalize_path)
  * **overwrite** (*False*) – whether to overwrite any existing files in
    `output_dir`
  * **save_mask_targets** (*False*) – whether to store the `mask_targets` on the
    dataset
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.export_segmentations(sample_collection, in_field, output_dir, rel_dir=None, update=True, overwrite=False, progress=None)

Exports the semantic segmentations, instance segmentations, or heatmaps
stored as in-database arrays in the specified field to images on disk.

Any labels without in-memory arrays are skipped.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the
    [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation),
    [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection),
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections), or
    [`fiftyone.core.labels.Heatmap`](fiftyone.core.labels.md#fiftyone.core.labels.Heatmap) field
  * **output_dir** – the directory in which to write the images
  * **rel_dir** (*None*) – an optional relative directory to strip from each input
    filepath to generate a unique identifier that is joined with
    `output_dir` to generate an output path for each image. This
    argument allows for populating nested subdirectories in
    `output_dir` that match the shape of the input paths. The path is
    converted to an absolute path (if necessary) via
    [`fiftyone.core.storage.normalize_path()`](fiftyone.core.storage.md#fiftyone.core.storage.normalize_path)
  * **update** (*True*) – whether to delete the arrays from the database
  * **overwrite** (*False*) – whether to overwrite any existing files in
    `output_dir`
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.import_segmentations(sample_collection, in_field, update=True, delete_images=False, progress=None)

Imports the semantic segmentations, instance segmentations, or heatmaps
stored on disk in the specified field to in-database arrays.

Any labels without images on disk are skipped.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the
    [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation),
    [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection),
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections), or
    [`fiftyone.core.labels.Heatmap`](fiftyone.core.labels.md#fiftyone.core.labels.Heatmap) field
  * **update** (*True*) – whether to delete the image paths from the labels
  * **delete_images** (*False*) – whether to delete any imported images from disk
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.transform_segmentations(sample_collection, in_field, targets_map, output_dir=None, rel_dir=None, update=True, update_mask_targets=False, overwrite=False, progress=None)

Transforms the segmentations in the given field according to the
provided targets map.

This method can be used to transform between grayscale and RGB masks, or it
can be used to edit the pixel values or colors of masks without changing
the number of channels.

Note that any pixel values not in `targets_map` will be zero in the
transformed masks.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation)
    field
  * **targets_map** – a dict mapping existing pixel values (2D masks) or RGB hex
    strings (3D masks) to new pixel values or RGB hex strings to use.
    You may convert between grayscale and RGB using this argument
  * **output_dir** (*None*) – an optional directory in which to write the
    transformed images
  * **rel_dir** (*None*) – an optional relative directory to strip from each input
    filepath to generate a unique identifier that is joined with
    `output_dir` to generate an output path for each image. This
    argument allows for populating nested subdirectories in
    `output_dir` that match the shape of the input paths. The path is
    converted to an absolute path (if necessary) via
    [`fiftyone.core.storage.normalize_path()`](fiftyone.core.storage.md#fiftyone.core.storage.normalize_path)
  * **update** (*True*) – whether to update the mask paths on the instances
  * **update_mask_targets** (*False*) – whether to update the mask targets on the
    dataset to reflect the transformed targets
  * **overwrite** (*False*) – whether to overwrite any existing files in
    `output_dir`
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.segmentations_to_detections(sample_collection, in_field, out_field, mask_targets=None, mask_types='stuff', output_dir=None, rel_dir=None, overwrite=False, progress=None)

Converts the semantic segmentations masks in the specified field of the
collection into [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) with instance
masks populated.

Each `"stuff"` class will be converted to a single
[`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection) whose instance mask spans all
region(s) of the class.

Each `"thing"` class will result in one
[`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection) instance per connected region of
that class in the segmentation.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation)
    field to convert
  * **out_field** – the name of the
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field to populate
  * **mask_targets** (*None*) – a dict mapping pixel values (2D masks) or RGB hex
    strings (3D masks) to label strings defining which object classes
    to label and which pixel values to use for each class. If omitted,
    all labels are assigned to the pixel values
  * **mask_types** ( *"stuff"*) – 

    whether the classes are `"stuff"` (amorphous
    regions of pixels) or `"thing"` (connected regions, each
    representing an instance of the thing). Can be any of the
    following:
    - `"stuff"` if all classes are stuff classes
    - `"thing"` if all classes are thing classes
    - a dict mapping pixel values (2D masks) or RGB hex strings (3D
      masks) to `"stuff"` or `"thing"` for each class
  * **output_dir** (*None*) – an optional output directory in which to write
    instance segmentation images. If none is provided, the instance
    segmentations are stored in the database
  * **rel_dir** (*None*) – an optional relative directory to strip from each input
    filepath to generate a unique identifier that is joined with
    `output_dir` to generate an output path for each instance
    segmentation image. This argument allows for populating nested
    subdirectories in `output_dir` that match the shape of the input
    paths. The path is converted to an absolute path (if necessary) via
    [`fiftyone.core.storage.normalize_path()`](fiftyone.core.storage.md#fiftyone.core.storage.normalize_path)
  * **overwrite** (*False*) – whether to overwrite any existing files in
    `output_dir`
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.binarize_instances(sample_collection, in_field, threshold=1, output_dir=None, rel_dir=None, overwrite=False, progress=None)

Binarizes the instance segmentations in the specified field according to
the provided threshold.

Each instance mask is updated in-place with `mask >= threshold`.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of a
    [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection) or
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field containing instance
    segmentations
  * **threshold** (*1*) – the threshold for “instance” pixels
  * **output_dir** (*None*) – an optional output directory in which to write the
    instance segmentation images. If none is provided, the
    segmentations are overwritten in-place, either on disk or in the
    database
  * **rel_dir** (*None*) – an optional relative directory to strip from each input
    filepath to generate a unique identifier that is joined with
    `output_dir` to generate an output path for each instance
    segmentation image. This argument allows for populating nested
    subdirectories in `output_dir` that match the shape of the input
    paths. The path is converted to an absolute path (if necessary) via
    [`fiftyone.core.storage.normalize_path()`](fiftyone.core.storage.md#fiftyone.core.storage.normalize_path)
  * **overwrite** (*False*) – whether to overwrite any existing files in
    `output_dir`
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.instances_to_polylines(sample_collection, in_field, out_field, tolerance=2, filled=True, progress=None)

Converts the instance segmentations in the specified field of the
collection into [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) instances.

For detections with masks, the returned polylines will trace the boundaries
of the masks; otherwise, the polylines will trace the bounding boxes
themselves.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections)
    field to convert
  * **out_field** – the name of the [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines)
    field to populate
  * **tolerance** (*2*) – a tolerance, in pixels, when generating approximate
    polylines for each region. Typical values are 1-3 pixels
  * **filled** (*True*) – whether the polylines should be filled
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.segmentations_to_polylines(sample_collection, in_field, out_field, mask_targets=None, mask_types='stuff', tolerance=2, progress=None)

Converts the semantic segmentations masks in the specified field of the
collection into [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) instances.

Each `"stuff"` class will be converted to a single
[`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) that may contain multiple disjoint
shapes capturing the class.

Each `"thing"` class will result in one
[`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) instance per connected region of
that class.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Segmentation`](fiftyone.core.labels.md#fiftyone.core.labels.Segmentation)
    field to convert
  * **out_field** – the name of the
    [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) field to populate
  * **mask_targets** (*None*) – a dict mapping pixel values (2D masks) or RGB hex
    strings (3D masks) to label strings defining which object classes
    to label and which pixel values to use for each class. If omitted,
    all labels are assigned to the pixel values
  * **mask_types** ( *"stuff"*) – 

    whether the classes are `"stuff"` (amorphous
    regions of pixels) or `"thing"` (connected regions, each
    representing an instance of the thing). Can be any of the
    following:
    - `"stuff"` if all classes are stuff classes
    - `"thing"` if all classes are thing classes
    - a dict mapping pixel values (2D masks) or RGB hex strings (3D
      masks) to `"stuff"` or `"thing"` for each class
  * **tolerance** (*2*) – a tolerance, in pixels, when generating approximate
    polylines for each region. Typical values are 1-3 pixels
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.classification_to_detections(sample_collection, in_field, out_field, progress=None)

Converts the [`fiftyone.core.labels.Classification`](fiftyone.core.labels.md#fiftyone.core.labels.Classification) field of the
collection into a [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field containing
a single detection whose bounding box spans the entire image.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Classification`](fiftyone.core.labels.md#fiftyone.core.labels.Classification)
    field
  * **out_field** – the name of the [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections)
    field to populate
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.classifications_to_detections(sample_collection, in_field, out_field, progress=None)

Converts the [`fiftyone.core.labels.Classifications`](fiftyone.core.labels.md#fiftyone.core.labels.Classifications) field of the
collection into a [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field containing
detections whose bounding boxes span the entire image with one detection
for each classification.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Classifications`](fiftyone.core.labels.md#fiftyone.core.labels.Classifications)
    field
  * **out_field** – the name of the [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections)
    field to populate
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.index_to_instance(sample_collection, label_field, index_attr='index', clear_index=False, progress=None)

Populates [`fiftyone.core.labels.Instance`](fiftyone.core.labels.md#fiftyone.core.labels.Instance) values in the

```
``
```

instance\`\`attribute of the specified label field based on the values in
the specified index attribute.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **label_field** – the label field to process. Supported types are
    [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection),
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections),
    [`fiftyone.core.labels.Polyline`](fiftyone.core.labels.md#fiftyone.core.labels.Polyline),
    [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines),
    [`fiftyone.core.labels.Keypoint`](fiftyone.core.labels.md#fiftyone.core.labels.Keypoint), and
    [`fiftyone.core.labels.Keypoints`](fiftyone.core.labels.md#fiftyone.core.labels.Keypoints)
  * **index_attr** ( *"index"*) – the attribute whose unique values define the
    object instances. When `index_attr="index"` specifically, the
    `(label, index)` of each object is used as the unique identifier.
    Otherwise, the `index_attr` values alone are used. In either
    case, any objects whose index attribute is None/missing are not
    assigned an `instance`
  * **clear_index** (*False*) – whether to clear the values in `index_attr`
    (True) or leave them (False) after populating the `instance`
    attribute
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.perform_nms(sample_collection, in_field, out_field=None, iou_thresh=0.5, confidence_thresh=None, classwise=True, progress=None)

Performs non-maximum suppression (NMS) on the specified
[`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field.

NMS is a post-processing technique used in object detection to eliminate
duplicate detections and select the most relevant detected objects. This
helps reduce false positives.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **in_field** – the name of the [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections)
    field
  * **out_field** (*None*) – the name of the
    [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) field to populate. If not
    specified, the input field is updated in-place
  * **iou_thresh** (*0.5*) – an intersection over union (IoU) threshold to use.
    This determines the minimum overlap required between bounding boxes
    to be considered duplicates. Bounding boxes with IoU values greater
    than or equal to this threshold will be suppressed
  * **confidence_thresh** (*None*) – a minimum confidence score required for a
    detection to be considered valid. Detections with confidence scores
    lower than this threshold will be discarded
  * **classwise** (*True*) – whether to treat each class `label` separately
    (True) or suppress all detections jointly (False)
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead

### fiftyone.utils.labels.detections_3d_to_cuboids_2d(sample_collection: ~fiftyone.core.collections.SampleCollection, spatial_slice_name: str, camera_slice_name: str, in_field: str, out_field: str, transformations: ~typing.Dict[str, ~typing.List[~typing.Tuple[list[float] | ~numpy.ndarray, list[list[float]] | ~numpy.ndarray]]], camera_params: ~typing.Dict[str, ~typing.Dict[str, ~typing.Any]], forward_transform_flags: ~typing.Dict[str, ~typing.List[bool]] | None = None, camera_model: ~typing.Callable = <function pinhole_projector>, transformation_key_field: str = 'id', camera_key_field: str = 'id', progress=None)

High-level orchestration of 3D → 2D label conversion. Processes the
`in_field` on the `spatial_slice_name` slice of a grouped sample
collection, uses the transformations and camera parameters to convert the
labels to 2D polylines, and saves them to the `out_field` on the
`camera_slice_name` slice.

* **Parameters:**
  * **sample_collection** – a
    [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection)
  * **spatial_slice_name** – the name of the spatial slice in the sample_collection
  * **camera_slice_name** – the name of the camera slice in the sample_collection
  * **in_field** – the name of the [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection) field
    containing 3D labels to convert
  * **out_field** – the name of the [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines)
    field to populate with 2D cuboids
  * **transformations** – a dict mapping `transformation_key_field` to a list of
    transformation tuples (translation, rotation) for each sample in the
    sample_collection. Translation is a 3-element list or np.ndarray,
    and rotation is a (3, 3) list of lists or np.ndarray representing a
    rotation matrix.
  * **camera_params** – a dict mapping `camera_key_field` to per-camera
    parameter dicts required by `camera_model`. Each dict must include
    an `"intrinsics"` 3x3 (or 4x4) matrix if using the default pinhole
    camera model; additional keys such as distortion parameters may be
    provided depending on the model
  * **forward_transform_flags** – an optional dict mapping
    `transformation_key_field` to lists of booleans indicating whether
    to apply forward or inverse transformations for each transform in
    the list of transformations for each sample
  * **camera_model** (*fou3d.pinhole_projector*) – a callable that takes 3D points
    in the camera coordinate system and the camera parameters dict and
    returns the projected 2D points in pixel coordinates
  * **transformation_key_field** ( *"id"*) – the key field to use for looking up
    transformations for each sample
  * **camera_key_field** ( *"id"*) – the key field to use for looking up camera
    parameters for each camera sample
  * **progress** (*None*) – whether to render a progress bar (True/False), use the
    default value `fiftyone.config.show_progress_bars` (None), or a
    progress callback function to invoke instead