Annotations

Annotations and annotation drivers provide a unified way to draw annotations on different rendering backends. Currently, two annotation drivers are implemented:

• PanoramaMediaAnnotationDriver allows you to draw on panoramasdk.media object, and

• OpenCVImageAnnotationDriver allows you to draw on an OpenCV image (numpy array) object.

Two types of annotations can be drawn: labels and rectangles. Not all annotation drivers necessarily implement all features specified by annotations, for example, one driver might decide to ignore colors.

Using annotations

You can create one or more annotation driver instances at the beginning of the video frame processing loop, depending on the available backends. During the process of a single frame, you are expected to collect all annotations to be drawn on the frame in a python collection (for example, in a list). When the processing is finished, you can call the render() method on any number of drivers, passing the same collection of annotations. All coordinates used in annotation are normalized to the range of [0; 1).

Example usage:

import panoramasdk
from backpack.annotation import (
    Point, LabelAnnotation, RectAnnotation, TimestampAnnotation,
    OpenCVImageAnnotationDriver,
    PanoramaMediaAnnotationDriver
)

class Application(panoramasdk.node):

    def __init__(self):
        super().__init__()
        # self.skyline = ...
        self.panorama_driver = PanoramaMediaAnnotationDriver()
        self.cv2_driver = OpenCVImageAnnotationDriver()

    # called from video processing loop:
    def process_streams(self):
        streams = self.inputs.video_in.get()
        for idx, stream in enumerate(streams):
            annotations = [
                TimestampAnnotation(),
                RectAnnotation(point1=Point(0.1, 0.1), point2=Point(0.9, 0.9)),
                LabelAnnotation(point=Point(0.5, 0.5), text='Hello World!')
            ]
            self.panorama_driver.render(annotations, stream)

            # TODO: eventually multiplex streams to a single frame
            if idx == 0:
                rendered = self.cv2_driver.render(annotations, stream.image.copy())
                # self.skyline.put(rendered)

For more information, refer to the annotation API documentation.