The implementation is inspired by the Keras implementations from https://github.com/keras-team/keras-applications/blob/master/keras_applications/resnet50.py and https://github.com/matterport/Mask_RCNN/blob/master/mrcnn/model.py.
You will find pre-trained weights and an example file to run this gist here https://github.com/pvdhove/owl-resnet.