TypeError: unhashable type: 'numpy.ndarray' when saving test results with Custom3D dataset

[joao-sgoncalves]

Checklist

• I have searched for similar issues.
• I have tested with the latest development wheel.
• I have checked the release documentation and the latest documentation (for master branch).

Describe the issue

Hello,

First of all, thank you for the awesome library.

We are trying to train the RandLANet model with a custom dataset to perform 3D semantic segmentation.
For that we are using the Custom3D dataset which, from our understanding, is the class to use if we need our own dataset.

We created a folder for our dataset with three folders inside, like expected by the Custom3D dataset class ("Expect point clouds to be in npy format with train, val and test files in separate folders.").

To each of this folders we saved our training, validation and test files, in the expected format (x, y, z, class, feat_1, feat_2, ..., feat_n).

We also had to override the get_label_to_names static method in the Custom3D class so that it returned our own label mappings, instead of the ones that were implemented.

We managed to train the model on the custom dataset using this class, using the run_train function of the pipeline, but when we tried evaluating the model performance (run_test function of the pipeline), it threw the error described below.

Could you help out with this issue?

Also, is this the correct approach to train models on custom datasets in Open3D?

Thanks for your help.

Steps to reproduce the bug

import pathlib
import numpy as np
import open3d as o3d
import open3d.ml as ml3d
import open3d.ml.tf


@staticmethod
def get_label_to_names():
    return {
        0: "unclassified",
        1: "bunny",
    }


# Create custom dataset

bunny_mesh = o3d.data.BunnyMesh()
mesh = o3d.io.read_triangle_mesh(bunny_mesh.path)
pcd = mesh.sample_points_uniformly(number_of_points=500)

points = np.asarray(pcd.points)
labels = np.ones(shape=500)

train_dataset = np.column_stack((points, labels))
val_dataset = train_dataset
test_dataset = points

pathlib.Path("custom/train").mkdir(parents=True, exist_ok=True)
np.save("custom/train/bunny.npy", train_dataset)

pathlib.Path("custom/val").mkdir(parents=True, exist_ok=True)
np.save("custom/val/bunny.npy", val_dataset)

pathlib.Path("custom/test").mkdir(parents=True, exist_ok=True)
np.save("custom/test/bunny.npy", test_dataset)

# Train model using custom dataset

framework = "tf"
config = ml3d.utils.Config.load_from_file("randlanet.yml")

Dataset = ml3d.utils.get_module("dataset", config.dataset.name)
Dataset.get_label_to_names = get_label_to_names
dataset = Dataset(**config.dataset)

Model = ml3d.utils.get_module("model", config.model.name, framework)
model = Model(**config.model)

Pipeline = ml3d.utils.get_module("pipeline", config.pipeline.name, framework)
pipeline = Pipeline(model, dataset, **config.pipeline)

pipeline.run_train()

pipeline.run_test()


### randlanet.yml ###

dataset:
  name: Custom3D
  dataset_path: custom
  train_dir: train
  val_dir: val
  test_dir: test
model:
  name: RandLANet
  batcher: DefaultBatcher
  ckpt_path: # path/to/your/checkpoint
  num_neighbors: 16
  num_layers: 4
  num_points: 65536
  num_classes: 1
  ignored_label_inds: [0]
  sub_sampling_ratio: [4, 4, 4, 4]
  in_channels: 3
  dim_features: 8
  dim_output: [16, 64, 128, 256]
  grid_size: 0.06
  augment:
    recenter:
      dim: [0, 1]
pipeline:
  name: SemanticSegmentation
  optimizer:
    lr: 0.001
  batch_size: 4
  main_log_dir: ./logs
  max_epoch: 1
  save_ckpt_freq: 5
  scheduler_gamma: 0.9886
  test_batch_size: 1
  train_sum_dir: ./train_log
  val_batch_size: 2
  summary:
    record_for: []
    max_pts:
    use_reference: false
    max_outputs: 1

Error message

File .venv/lib/python3.10/site-packages/open3d/_ml3d/datasets/customdataset.py:223, in Custom3D.save_test_result(self, results, attr)
220 make_dir(path)
222 pred = results['predict_labels']
--> 223 pred = np.array(self.label_to_names[pred])
225 store_path = join(path, name + '.npy')
226 np.save(store_path, pred)

TypeError: unhashable type: 'numpy.ndarray'

Expected behavior

We would expect that the save_test_result function from the Custom3D dataset didn't fail by trying to use a numpy array to access the label_to_names dict by key.

Open3D, Python and System information

- Operating system: macOS Ventura 13.4.1
- Python version: 3.10.12
- Open3D version: 0.17.0
- System type: x64
- Is this remote workstation?: no
- How did you install Open3D?: pip

Additional information

No response