Read heterogenous nonlist PLY properties as arrays

Summary:
In the original implementation, I had considered PLY properties where there are mixed types of elements in a property to be rare and basically unimportant, so the implementation is very naive.

If we want to support pointcloud PLY files, we need to handle at least the subcase where there are no lists efficiently because this seems to be very common there.

Reviewed By: nikhilaravi, gkioxari

Differential Revision: D22573315

fbshipit-source-id: db6f29446d4e555a2e2b37d38c8e4450d061465b

tests/test_ply_io.py

@@ -5,6 +5,7 @@ import unittest
 from io import BytesIO, StringIO
 from tempfile import NamedTemporaryFile, TemporaryFile
 
+import numpy as np
 import pytorch3d.io.ply_io
 import torch
 from common_testing import TestCaseMixin
@@ -125,7 +126,8 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
             self.assertTupleEqual(data["face"].shape, (6, 4))
             self.assertClose([0, 1, 2, 3], data["face"][0])
             self.assertClose([3, 7, 4, 0], data["face"][5])
-            self.assertTupleEqual(data["vertex"].shape, (8, 3))
+            [vertex0] = data["vertex"]
+            self.assertTupleEqual(vertex0.shape, (8, 3))
             irregular = data["irregular_list"]
             self.assertEqual(len(irregular), 3)
             self.assertEqual(type(irregular), list)
@@ -309,6 +311,49 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
                     file.close()
             self.assertLess(lengths[False], lengths[True], "ascii should be longer")
 
+    def test_heterogenous_property(self):
+        ply_file_ascii = "\n".join(
+            [
+                "ply",
+                "format ascii 1.0",
+                "element vertex 8",
+                "property float x",
+                "property int y",
+                "property int z",
+                "end_header",
+                "0 0 0",
+                "0 0 1",
+                "0 1 1",
+                "0 1 0",
+                "1 0 0",
+                "1 0 1",
+                "1 1 1",
+                "1 1 0",
+            ]
+        )
+        ply_file_binary = "\n".join(
+            [
+                "ply",
+                "format binary_little_endian 1.0",
+                "element vertex 8",
+                "property uchar x",
+                "property char y",
+                "property char z",
+                "end_header",
+                "",
+            ]
+        )
+        data = [0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0]
+        stream_ascii = StringIO(ply_file_ascii)
+        stream_binary = BytesIO(ply_file_binary.encode("ascii") + bytes(data))
+        X = np.array([[0, 0, 0, 0, 1, 1, 1, 1]]).T
+        YZ = np.array([0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0])
+        for stream in (stream_ascii, stream_binary):
+            header, elements = _load_ply_raw(stream)
+            [x, yz] = elements["vertex"]
+            self.assertClose(x, X)
+            self.assertClose(yz, YZ.reshape(8, 2))
+
     def test_load_simple_binary(self):
         for big_endian in [True, False]:
             verts = (
@@ -386,10 +431,11 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
             self.assertClose([0, 1, 2, 3], data["face"][0])
             self.assertClose([3, 7, 4, 0], data["face"][5])
 
-            self.assertTupleEqual(data["vertex"].shape, (8, 3))
-            self.assertEqual(len(data["vertex1"]), 8)
-            self.assertClose(data["vertex"], data["vertex1"])
-            self.assertClose(data["vertex"].flatten(), list(map(float, verts)))
+            [vertex0] = data["vertex"]
+            self.assertTupleEqual(vertex0.shape, (8, 3))
+            self.assertEqual(len(data["vertex1"]), 3)
+            self.assertClose(vertex0, np.column_stack(data["vertex1"]))
+            self.assertClose(vertex0.flatten(), list(map(float, verts)))
 
             irregular = data["irregular_list"]
             self.assertEqual(len(irregular), 3)
@@ -413,7 +459,7 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
             self.assertEqual(mixed[1][0][0], base if big_endian else 256 * base)
 
             self.assertListEqual(
-                data["minus_ones"], [(-1, 255, -1, 65535, -1, 4294967295)]
+                data["minus_ones"], [-1, 255, -1, 65535, -1, 4294967295]
             )
 
     def test_bad_ply_syntax(self):
@@ -513,14 +559,14 @@ class TestMeshPlyIO(TestCaseMixin, unittest.TestCase):
         lines2 = lines.copy()
         lines2.insert(4, "property double y")
 
-        with self.assertRaisesRegex(ValueError, "Too little data for an element."):
+        with self.assertRaisesRegex(ValueError, "Inconsistent data for vertex."):
             _load_ply_raw(StringIO("\n".join(lines2)))
 
         lines2[-2] = "3.3 4.2"
         _load_ply_raw(StringIO("\n".join(lines2)))
 
         lines2[-2] = "3.3 4.3 2"
-        with self.assertRaisesRegex(ValueError, "Too much data for an element."):
+        with self.assertRaisesRegex(ValueError, "Inconsistent data for vertex."):
             _load_ply_raw(StringIO("\n".join(lines2)))
 
         # Now make the ply file actually be readable as a Mesh