BoundingBoxUtil

public final class BoundingBoxUtil

Helper class for converting values that represents bounding boxes into rectangles.

The class provides a static function to create bounding boxes as RectF from different types of configurations.

Generally, a bounding box could be represented by 4 float values, but the values could be interpreted in many ways. We now support 3 BoundingBoxUtil.Type of configurations, and the order of elements in each type is configurable as well.

Nested Classes

enum BoundingBoxUtil.CoordinateType Denotes if the coordinates are actual pixels or relative ratios. 
enum BoundingBoxUtil.Type Denotes how a bounding box is represented. 

Public Methods

static List<RectF>
convert(TensorBuffer tensor, int[] valueIndex, int boundingBoxAxis, BoundingBoxUtil.Type type, BoundingBoxUtil.CoordinateType coordinateType, int height, int width)
Creates a list of bounding boxes from a TensorBuffer which represents bounding boxes.

Inherited Methods

Public Methods

public static List<RectF> convert (TensorBuffer tensor, int[] valueIndex, int boundingBoxAxis, BoundingBoxUtil.Type type, BoundingBoxUtil.CoordinateType coordinateType, int height, int width)

Creates a list of bounding boxes from a TensorBuffer which represents bounding boxes.

Parameters
tensor holds the data representing some boxes.
valueIndex denotes the order of the elements defined in each bounding box type. An empty index array represent the default order of each bounding box type. For example, to denote the default order of BOUNDARIES, {left, top, right, bottom}, the index should be {0, 1, 2, 3}. To denote the order {left, right, top, bottom}, the order should be {0, 2, 1, 3}.

The index array can be applied to all bounding box types to adjust the order of their corresponding underlying elements.
boundingBoxAxis specifies the index of the dimension that represents bounding box. The size of that dimension is required to be 4. Index here starts from 0. For example, if the tensor has shape 4x10, the axis for bounding boxes is likely to be 0. Negative axis is also supported: -1 gives the last axis and -2 gives the second, .etc. theFor shape 10x4, the axis is likely to be 1 (or -1, equivalently).
type defines how values should be converted into boxes. See BoundingBoxUtil.Type
coordinateType defines how values are interpreted to coordinates. See BoundingBoxUtil.CoordinateType
height the height of the image which the boxes belong to. Only has effects when coordinateType is BoundingBoxUtil.CoordinateType.RATIO
width the width of the image which the boxes belong to. Only has effects when coordinateType is BoundingBoxUtil.CoordinateType.RATIO
Returns
  • A list of bounding boxes that the tensor represents. All dimensions except boundingBoxAxis will be collapsed with order kept. For example, given tensor with shape {1, 4, 10, 2} and boundingBoxAxis = 1, The result will be a list of 20 bounding boxes.
Throws
IllegalArgumentException if size of bounding box dimension (set by boundingBoxAxis) is not 4.
IllegalArgumentException if boundingBoxAxis is not in (-(D+1), D) where D is the number of dimensions of the tensor.
IllegalArgumentException if tensor has data type other than DataType.FLOAT32.