Get output from a model

Get the tensor output

Use PeekOutput to access the output of the tensor. PeekOutput returns a Tensor object, so you usually need to cast it to a TensorFloat or a TensorInt. For example:

worker.Execute(inputTensor);
TensorFloat outputTensor = worker.PeekOutput() as TensorFloat;

The result of PeekOutput is a shallow copy that points to the same memory as the original output, which means the following:

  • You don't need to use Dispose on the output.
  • If you change the output or you rerun the worker, both the worker output and the PeekOutput copy change.
  • If you use Dispose on the worker, the PeekOutput copy will also be disposed.

To take ownership of the original tensor instead, do either of the following:

  • Use TakeOwnership on the tensor after you use PeekOutput.
  • Use FinishExecutionAndDownloadOutput instead of PeekOutput. Sentis downloads the tensor from native memory.

If you use either method, you must Dispose of the tensor when you're finished with it.

When you read data from the tensor that PeekOutput returns, there might be a performance cost because Sentis waits for the model to finish running then downloads the data from the GPU or Burst to the CPU. You can read output from a model asynchronously to avoid this cost. You can also profile a model to understand more about the performance of a model.

To get intermediate tensors from layers other than the model outputs, refer to Get output from any layer.

Multiple outputs

If the model has multiple outputs, you can use each output name as a parameter in PeekOutput.

For example, the following code sample prints the output from each layer of the model.

using UnityEngine;
using Unity.Sentis;

public class GetMultipleOutputs : MonoBehaviour
{
    ModelAsset modelAsset;
    Model runtimeModel;
    IWorker worker;

    void Start()
    {
        // Create an input tensor
        TensorFloat inputTensor = new TensorFloat(new TensorShape(4), new[] { 2.0f, 1.0f, 3.0f, 0.0f });

        // Create runtime model
        runtimeModel = ModelLoader.Load(modelAsset);

        // Create engine and execute
        worker = WorkerFactory.CreateWorker(BackendType.GPUCompute, runtimeModel);
        worker.Execute(inputTensor);

        // Iterate through the output layer names of the model and print the output from each
        foreach (var outputName in runtimeModel.outputs)
        {
            TensorFloat outputTensor = worker.PeekOutput(outputName) as TensorFloat;
            // Make the tensor readable by downloading it to the CPU
            outputTensor.MakeReadable();
            outputTensor.PrintDataPart(10);
        }
    }
}

You can use the following methods to log tensor data to the Console window:

  • Print.
  • PrintDataPart, which prints the first elements from the tensor data.

Additional resources