Expose ALIKED feature extractor from LightGlue (#375)

Co-authored-by: Paul-Edouard Sarlin <15985472+sarlinpe@users.noreply.github.com>

hloc/extract_features.py

@@ -114,6 +114,17 @@
             "resize_max": 1600,
         },
     },
+    "aliked-n16": {
+        "output": "feats-aliked-n16",
+        "model": {
+            "name": "aliked",
+            "model_name": "aliked-n16",
+        },
+        "preprocessing": {
+            "grayscale": False,
+            "resize_max": 1024,
+        },
+    },
     # Global descriptors
     "dir": {
         "output": "global-feats-dir",

hloc/extractors/aliked.py

@@ -0,0 +1,26 @@
+from lightglue import ALIKED as ALIKED_
+
+from ..utils.base_model import BaseModel
+
+
+class ALIKED(BaseModel):
+    default_conf = {
+        "model_name": "aliked-n16",
+        "max_num_keypoints": -1,
+        "detection_threshold": 0.2,
+        "nms_radius": 2,
+    }
+    required_inputs = ["image"]
+
+    def _init(self, conf):
+        conf.pop("name")
+        self.model = ALIKED_(**conf)
+
+    def _forward(self, data):
+        features = self.model(data)
+
+        return {
+            "keypoints": [f for f in features["keypoints"]],
+            "keypoint_scores": [f for f in features["keypoint_scores"]],
+            "descriptors": [f.t() for f in features["descriptors"]],
+        }

hloc/match_features.py

@@ -35,6 +35,13 @@
             "features": "disk",
         },
     },
+    "aliked+lightglue": {
+        "output": "matches-aliked-lightglue",
+        "model": {
+            "name": "lightglue",
+            "features": "aliked",
+        },
+    },
     "superglue": {
         "output": "matches-superglue",
         "model": {