COCO annotations

The focus of this example is to introduce user to writer.CocoAnnotationsWriter module.

Usage

Execute in the BlenderProc main directory:

python run.py examples/advanced/coco_annotations/config.yaml examples/resources/camera_positions examples/advanced/coco_annotations/scene.blend examples/advanced/coco_annotations/output

examples/advanced/coco_annotations/config.yaml: path to the configuration file with pipeline configuration.
examples/resources/camera_positions: text file with parameters of camera positions.
examples/advanced/coco_annotations/scene.blend: path to the blend file with the basic scene.
examples/advanced/coco_annotations/output: path to the output directory.

Visualizing Annotations

You can use vis_coco_annotation.py with the following command to visualize the annotations blended over a rendered rgb image:

python scripts/vis_coco_annotation.py [-i <image index>] [-c <coco annotations json>] [-b <base folder of coco json and image files>]

Working Examples

With specific values:

python scripts/vis_coco_annotation.py -i 1 -c coco_annotations.json -b examples/advanced/coco_annotations/output/coco_data

Above are also the default values, i.e. for the same result call:

python scripts/vis_coco_annotation.py

Steps

Loads scene.blend: loader.BlendLoader module. The BlendLoader is used here as we always load the cp_category_id for each object, which is stored in the .blend file.
Creates a point light: lighting.LightLoader module.
Loads camera positions from camera_positions: camera.CameraLoader module.
Renders rgb: renderer.RgbRenderer module.
Renders instance segmentation: renderer.SegMapRenderer module.
Writes coco annotations: writer.CocoAnnotationsWriter module.

Config file

SegMapRenderer

  {
    "module": "renderer.SegMapRenderer",
    "config": {
      "map_by": ["instance", "class", "name"],
    }
  }

The renderer.SegMapRenderer needs to render both instance and class maps. The class is defined in terms of a custom property category_id which must be previously defined for each instance. The category_id can be either set in a custom Loader module or in a .blend file. We also add "name" to the mapping, s.t. we can later use the object's names for labeling the categories in the coco annotations writer.