Exporting model from ML-Agents to run inference in python with tensorflow

Unity Engine
,
1

As the title implies, I am working on a pipeline for taking a model trained in ML-Agents and exporting it such that I can run inference with the model from inside a python script using tensor flow. Informed by this and this forum post, my planned pipeline is:

  1. export model trained in ML-Agents to ONNX using tf2onnx
  2. import onnx model in python script
  3. create tensorflow representation in python with onnx-tx
  4. run inference using tensorflow similar to tutorial here: tutorials/tutorials/OnnxTensorflowImport.ipynb at master · onnx/tutorials · GitHub

Steps 1 and 2 seem to work but I am stuck on an error at step 3 when trying to create a tensorflow representation of the onnx model created in ML-Agents. Given a trained onnx model “model.onnx”, here is a simple python script that reproduces the error:

import onnx
from onnx_tf.backend import prepare
onnx_model = onnx.load('model.onnx')
tf_model = prepare(onnx_model)

The error I receive:

Traceback (most recent call last):
File “/home/ross/miniconda3/envs/autofly_py3/lib/python3.7/site-packages/tensorflow/python/framework/ops.py”, line 1654, in _create_c_op
c_op = pywrap_tf_session.TF_FinishOperation(op_desc)
tensorflow.python.framework.errors_impl.InvalidArgumentError: Input must be scalar but has rank 1 for ‘{{node one_hot}} = OneHot[T=DT_FLOAT, TI=DT_INT32, axis=-1](strided_slice__20, const_fold_opt__56, strided_slice_3, strided_slice_2)’ with input shapes: [2147483647], [1], [ ], [ ] and with computed input tensors: input[1] = <2>.

I realize that my problem may well be specific to my model.onnx file, but I am posting in the hopes that this is a more general problem others have seen and can help fix. For reference, I am using:

python==3.7.6
onnx=1.7.0
onnx-tf @ git+https://github.com/onnx/onnx-tensorflow@44c09275a803e04eeeb4e0d24c372adf1f9ff1f5
tensorboard==2.2.2
tensorflow==2.2.0
tensorflow-addons==0.10.0
tensorflow-estimator==2.2.0

2

Hi,
We do not support running the generated models outside of Unity as of today, but I think you will have more success using a TensorFlow model directly. In the results folder, look for the frozen_graph_def.pb file. It contains the TensorFlow model directly.
I do not know what the error you are getting is, but I suspect converting from TensorFlow to onnx and then back to TensorFlow using different libraries might loose some data.

3

Thank you for the response. A previous forum post ( https://discussions.unity.com/t/800269/2 ) had discouraged me from trying to directly use the frozen graph .pb file, but I will give it a shot. I will also reach out to the developer who supported ml-agents onnx integration (https://github.com/Unity-Technologies/ml-agents/pull/3101) as well as the onnx-tf developers to see if they have further insights.

1 Like