Improve documentation concerning the new config files

📚 Documentation Improvements

In short

Concerning: https://detectron2.readthedocs.io/en/latest/tutorials/configs.html Problem: Documentation does not seem to have been updated to reflect the new config files (.py rather than .yaml) Solution: Update the documentation

Problem description

FAIR recently published new Mask R-CNN baselines and this was my first introduction to the new config file that no longer relies on YAML files but on ‘raw’ .py files. I am trying to load the new baselines using the config files mentioned in the MODEL_ZOO (see this table). For example:

from detectron2 import model_zoo
model = model_zoo.get("new_baselines/mask_rcnn_regnetx_4gf_dds_FPN_400ep_LSJ.py", trained=True)

This gives

RuntimeError: new_baselines/mask_rcnn_regnetx_4gf_dds_FPN_400ep_LSJ not available in Model Zoo!

I have installed Detectron2 using the installation instructions. When looking up the documentation on configs, it seems that this has not been updated to reflect the new configs and still solely mentions YAML files.

Proposed solution

It could be that the CONFIG_PATH_TO_URL_SUFFIX dictionary in _ModelZooUrls class still has to be updated and that this is actually a bug (see here), but I find it hard to estimate wheter this is meant behavior (i.e. the new config file should be loaded differently) or a bug due to my limited understanding of the new config files. Either way, I therefore feel like the documentation on readthedocs should be updated to reflect the change from .yaml to .py.

[orbiskcw]

@ppwwyyxx One more question that recently came up while working with the detectron2 repo: What is the best way to extend a config from the model zoo? I expected something like this to work:

# In /path/to/custom_config.py

from detectron2.model_zoo.configs.new_baselines.mask_rcnn_regnetx_4gf_dds_FPN_400ep_LSJ import  (
    dataloader,
    lr_multiplier,
    model,
    optimizer,
    train,
)

train.max_iter = 10

But if I then try to load the new config with:

LazyConfig.load('/path/to/custom_config.py')

I get:

  File "/home/cas/Documents/repositories/detectron2-model-training/detectron2_model_training/config.py", line 98, in load
    return LazyConfig.load(config_path)
  File "/home/cas/Documents/repositories/detectron2-model-training/.venv/lib/python3.8/site-packages/detectron2/config/lazy.py", line 202, in load
    exec(compile(content, filename, "exec"), module_namespace)
  File "configs/default.py", line 1, in <module>
    from detectron2.model_zoo.configs.new_baselines.mask_rcnn_regnetx_4gf_dds_FPN_100ep_LSJ import (  # noqa
  File "/home/cas/Documents/repositories/detectron2-model-training/.venv/lib/python3.8/site-packages/detectron2/config/lazy.py", line 145, in new_import
    return old_import(name, globals, locals, fromlist=fromlist, level=level)
  File "/home/cas/Documents/repositories/detectron2-model-training/.venv/lib/python3.8/site-packages/detectron2/model_zoo/configs/new_baselines/mask_rcnn_regnetx_4gf_dds_FPN_100ep_LSJ.py", line 1, in <module>
    from .mask_rcnn_R_50_FPN_100ep_LSJ import (
  File "/home/cas/Documents/repositories/detectron2-model-training/.venv/lib/python3.8/site-packages/detectron2/config/lazy.py", line 145, in new_import
    return old_import(name, globals, locals, fromlist=fromlist, level=level)
  File "/home/cas/Documents/repositories/detectron2-model-training/.venv/lib/python3.8/site-packages/detectron2/model_zoo/configs/new_baselines/mask_rcnn_R_50_FPN_100ep_LSJ.py", line 13, in <module>
    train.init_checkpoint = ""
AttributeError: 'dict' object has no attribute 'init_checkpoint'

Could you confirm whether this is expected behavior or a bug? Could you clarify if it is possible to do this and if so, what the conditions / requirements are?

[ppwwyyxx]

https://github.com/facebookresearch/detectron2/blob/master/tools/lazyconfig_train_net.py is the training script to use these configs. We’ll add documentation soon.