Skeleton of ShapeNetCore class

Summary: Skeleton of ShapeNetCore class that loads ShapeNet v1 from a given directory to a Dataset object. Overrides _init_, _len_, and _getitem_ from torch.utils.data.Dataset. Currently getitem returns verts, faces and id_str, where id_str is a concatenation of synset_id and obj_id. Planning on adding support for loading ShapeNet v2, retrieving textures and returning wordnet synsets (not just ids) in next diffs.

Reviewed By: nikhilaravi

Differential Revision: D21986222

fbshipit-source-id: c2c515303f1898b6c495b52cb53c74d691585326

pytorch3d/datasets/shapenet/shapenet_core.py

+# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+
+import os
+import warnings
+from os import path
+
+import torch
+from pytorch3d.io import load_obj
+
+
+class ShapeNetCore(torch.utils.data.Dataset):
+    """
+    This class loads ShapeNet v.1 from a given directory into a Dataset object.
+    """
+
+    def __init__(self, data_dir):
+        """
+        Stores each object's synset id and models id from data_dir.
+        Args:
+            data_dir (path): Path to shapenet data
+        """
+        self.data_dir = data_dir
+
+        # List of subdirectories of data_dir each containing a category of models.
+        # The name of each subdirectory is the wordnet synset offset of that category.
+        wnsynset_list = [
+            wnsynset
+            for wnsynset in os.listdir(data_dir)
+            if path.isdir(path.join(data_dir, wnsynset))
+        ]
+
+        # Extract synset_id and model_id of each object from directory names.
+        # Each grandchildren directory of data_dir contains an object, and the name
+        # of the directory is the object's model_id.
+        self.synset_ids = []
+        self.model_ids = []
+        for synset in wnsynset_list:
+            for model in os.listdir(path.join(data_dir, synset)):
+                if not path.exists(path.join(data_dir, synset, model, "model.obj")):
+                    msg = """ model.obj not found in the model directory %s
+                        under synset directory %s.""" % (
+                        model,
+                        synset,
+                    )
+                    warnings.warn(msg)
+                else:
+                    self.synset_ids.append(synset)
+                    self.model_ids.append(model)
+
+    def __len__(self):
+        """
+        Returns # of total models in shapenet core
+        """
+        return len(self.model_ids)
+
+    def __getitem__(self, idx):
+        """
+        Read a model by the given index.
+        Returns:
+            dictionary with following keys:
+            - verts: FloatTensor of shape (V, 3).
+            - faces: LongTensor of shape (F, 3) which indexes into the verts tensor.
+            - synset_id (str): synset id
+            - model_id (str): model id
+        """
+        model = {}
+        model["synset_id"] = self.synset_ids[idx]
+        model["model_id"] = self.model_ids[idx]
+        model_path = path.join(
+            self.data_dir, model["synset_id"], model["model_id"], "model.obj"
+        )
+        model["verts"], faces, _ = load_obj(model_path)
+        model["faces"] = faces.verts_idx
+        return model

tests/test_shapenet_core.py

+# Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
+"""
+Sanity checks for loading ShapeNet Core v1.
+"""
+import os
+import random
+import unittest
+import warnings
+
+import torch
+from common_testing import TestCaseMixin
+from pytorch3d.datasets.shapenet.shapenet_core import ShapeNetCore
+
+
+SHAPENET_PATH = None
+
+
+class TestShapenetCore(TestCaseMixin, unittest.TestCase):
+    def test_load_shapenet_core(self):
+
+        # The ShapeNet dataset is not provided in the repo.
+        # Download this separately and update the `shapenet_path`
+        # with the location of the dataset in order to run this test.
+        if SHAPENET_PATH is None or not os.path.exists(SHAPENET_PATH):
+            url = "https://www.shapenet.org/"
+            msg = """ShapeNet data not found, download from %s, save it at the path %s,
+                update SHAPENET_PATH at the top of the file, and rerun""" % (
+                url,
+                SHAPENET_PATH,
+            )
+            warnings.warn(msg)
+            return True
+
+        # Load ShapeNetCore without specifying any particular categories.
+        shapenet_dataset = ShapeNetCore(SHAPENET_PATH)
+
+        # Count the number of grandchildren directories (which should be equal to
+        # the total number of objects in the dataset) by walking through the given
+        # directory.
+        wnsynset_list = [
+            wnsynset
+            for wnsynset in os.listdir(SHAPENET_PATH)
+            if os.path.isdir(os.path.join(SHAPENET_PATH, wnsynset))
+        ]
+        model_num_list = [
+            (len(next(os.walk(os.path.join(SHAPENET_PATH, wnsynset)))[1]))
+            for wnsynset in wnsynset_list
+        ]
+        # Check total number of objects in the dataset is correct.
+        self.assertEqual(len(shapenet_dataset), sum(model_num_list))
+
+        # Randomly retrieve an object from the dataset.
+        rand_obj = random.choice(shapenet_dataset)
+        self.assertEqual(len(rand_obj), 4)
+        # Check that data types and shapes of items returned by __getitem__ are correct.
+        verts, faces = rand_obj["verts"], rand_obj["faces"]
+        self.assertTrue(verts.dtype == torch.float32)
+        self.assertTrue(faces.dtype == torch.int64)
+        self.assertEqual(verts.ndim, 2)
+        self.assertEqual(verts.shape[-1], 3)
+        self.assertEqual(faces.ndim, 2)
+        self.assertEqual(faces.shape[-1], 3)