detection_utils.py

import math

import numpy as np
import PIL
import torch


############################################
# Predict detections with MegaDetector v5a model
def predict_md(
    im,
    megadetector_model,  # Megadet_Models[mega_model_input]
    size=640,
):

    # resize image
    g = size / max(im.size)  # multipl factor to make max size of the image equal to input size
    im = im.resize((int(x * g) for x in im.size), PIL.Image.Resampling.LANCZOS)  # resize
    # device: yolov5's select_device expects a CUDA index ('0') or 'cpu', not 'cuda'
    md_device = "0" if torch.cuda.is_available() else "cpu"

    # megadetector
    MD_model = torch.hub.load(
        "ultralytics/yolov5",  # repo_or_dir
        "custom",  # model
        megadetector_model,  # args for callable model
        skip_validation=True,  # avoid GitHub API rate limit (403)
        device=md_device,
        trust_repo=True,
    )

    ## detect objects
    # vars(results).keys(): imgs, pred, names, files, times, xyxy, xywh, xyxyn, xywhn, n, t, s
    results = MD_model(im)

    return results


##########################################
def crop_animal_detections(img_in, yolo_results, likelihood_th):

    ## Extract animal crops
    list_labels_as_str = [i for i in yolo_results.names.values()]  # ['animal', 'person', 'vehicle']
    list_np_animal_crops = []
    list_animal_bboxes = []  # detection rows [x1,y1,x2,y2,conf,label] matching each crop

    # image to crop (scale as input for megadetector)
    img_in = img_in.resize((yolo_results.ims[0].shape[1], yolo_results.ims[0].shape[0]))
    # for every detection in the img
    for det_array in yolo_results.xyxy:
        # for every detection
        for j in range(det_array.shape[0]):
            # compute coords around bbox rounded to the nearest integer (for pasting later)
            xmin_rd = int(math.floor(det_array[j, 0]))  # int() should suffice?
            ymin_rd = int(math.floor(det_array[j, 1]))

            xmax_rd = int(math.ceil(det_array[j, 2]))
            ymax_rd = int(math.ceil(det_array[j, 3]))

            pred_llk = det_array[j, 4]
            pred_label = det_array[j, 5]
            # keep animal crops above threshold
            if (pred_label == list_labels_as_str.index("animal")) and (pred_llk >= likelihood_th):
                area = (xmin_rd, ymin_rd, xmax_rd, ymax_rd)

                # pdb.set_trace()
                crop = img_in.crop(area)  # Image.fromarray(img_in).crop(area)
                crop_np = np.asarray(crop)

                # add to list
                list_np_animal_crops.append(crop_np)
                list_animal_bboxes.append(det_array[j, :].tolist())

    return list_np_animal_crops, list_animal_bboxes