Configs in this directory implement the legacy configs used by MMDetection V1.x and its model zoos.
To help users convert their models from V1.x to MMDetection V2.0, we provide v1.x configs to inference the converted v1.x models.
Due to the BC-breaking changes in MMDetection V2.0 from MMDetection V1.x, running inference with the same model weights in these two version will produce different results. The difference will cause within 1% AP absolute difference as can be found in the following table.
## Usage
To upgrade the model version, the users need to do the following steps.
### 1. Convert model weights
There are three main difference in the model weights between V1.x and V2.0 codebases.
1. Since the class order in all the detector's classification branch is reordered, all the legacy model weights need to go through the conversion process.
2. The regression and segmentation head no longer contain the background channel. Weights in these background channels should be removed to fix in the current codebase.
3. For two-stage detectors, their wegihts need to be upgraded since MMDetection V2.0 refactors all the two-stage detectors with `RoIHead`.
The users can do the same modification as mentioned above for the self-implemented
detectors. We provide a scripts `tools/model_converters/upgrade_model_version.py` to convert the model weights in the V1.x model zoo.