title: What parameters do I change to train a pytorch model from scratch?
body: <p>I followed this tutorial to train a pytorch model for instance segmentation:
  <a href="https://pytorch.org/tutorials/intermediate/torchvision_tutorial.html" rel="nofollow noreferrer">https://pytorch.org/tutorials/intermediate/torchvision_tutorial.html</a></p>
  <p>I would not like to train a model on entirely different data and classes, totally unrelated to COCO. What changes do I need to make to retrain the model. From my reading I'm guessing besides have the correct number of classes I just need to train this line:</p>
  <pre><code>model = torchvision.models.detection.maskrcnn_resnet50_fpn(pretrained=True)
  </code></pre>
  <p>to</p>
  <pre><code>model = torchvision.models.detection.maskrcnn_resnet50_fpn(pretrained=False)
  </code></pre>
  <p>But I notice there is another parameters: <code>pretrained_backbone=True, trainable_backbone_layers=None</code> should they be changed too?</p>