adds cvat xml to pascal voc formatter

cvat/requirements/base.txt

@@ -22,3 +22,4 @@ scipy==1.0.1
 sqlparse==0.2.4
 django-sendfile==0.3.11
 dj-pagination==2.3.2
+pascal-voc-writer==0.1.4

cvat/scripts/pascal_voc.py

@@ -0,0 +1,42 @@
+import os
+import argparse
+import xml.etree.ElementTree
+from PIL import Image
+from pascal_voc_writer import Writer
+
+
+def read_cvat_xml(xml_file, img_dir, annotation_dir):
+    os.makedirs(annotation_dir)
+    cvat_xml = xml.etree.ElementTree.parse(xml_file)
+
+    for img_tag in cvat_xml.findall('image'):
+        filename = img_tag.get('name')
+
+        filepath = os.path.join(img_dir, filename)
+        with Image.open(filepath) as img:
+            width, height = img.size
+
+        writer = Writer(filepath, width, height)
+
+        for box in img_tag.findall('box'):
+            label = box.get('label')
+            xmin = float(box.get('xtl'))
+            ymin = float(box.get('ytl'))
+            xmax = float(box.get('xbr'))
+            ymax = float(box.get('ybr'))
+
+            writer.addObject(label, xmin, ymin, xmax, ymax)
+
+        fname = os.path.splitext(filename)[0] + '.xml'
+        writer.save(os.path.join(annotation_dir, fname))
+
+
+parser = argparse.ArgumentParser(description='Transforms CVAT XML to Pascal '
+                                             'VOC format')
+parser.add_argument('cvat_xml', type=argparse.FileType())
+parser.add_argument('img_dir')
+parser.add_argument('annotation_dir')
+
+if __name__ == '__main__':
+    args = vars(parser.parse_args())
+    read_cvat_xml(args['cvat_xml'], args['img_dir'], args['annotation_dir'])