Catch bad JSON input, added missing test file

opendm/config.py

@@ -159,7 +159,7 @@ def config():
 
     parser.add_argument('--cameras',
                         default='',
-                        metavar='<string>',
+                        metavar='<json>',
                         type=path_or_json_string,
                         help='Use the camera parameters computed from '
                              'another dataset instead of calculating them. '

opendm/osfm.py

@@ -89,8 +89,9 @@ class OSFMContext:
             # check for cameras
             if args.cameras:
                 try:
+                    camera_overrides = camera.get_opensfm_camera_models(args.cameras)
                     with open(os.path.join(self.opensfm_project_path, "camera_models_overrides.json"), 'w') as f:
-                        f.write(json.dumps(camera.get_opensfm_camera_models(args.cameras)))
+                        f.write(json.dumps(camera_overrides))
                     log.ODM_DEBUG("Wrote camera_models_overrides.json to OpenSfM directory")
                 except Exception as e:
                     log.ODM_WARNING("Cannot set camera_models_overrides.json: %s" % str(e))

tests/assets/gcp_extras.txt

@@ -0,0 +1,4 @@
+WGS84 UTM 16N
+609924.8180680283 4950688.771811823 171.662982 1331 350 DJI_0002.JPG gcp1
+609924.8180680283 4950688.771811823 171.662982 2028 87 DJI_0003.JPG gcp1
+609924.8180680283 4950688.771811823 171.662982 2101 1181 DJI_0004.JPG gcp1