The implementation of interpolatation in STDCHead isn't consistent with config setting.

[jiehuang165]

Checklist

1. I have searched related issues but cannot get the expected help.
2. The bug has not been fixed in the latest version.

Describe the bug
When calculating losses in Moudle STDCHead, seg_logit needs to be resized back to the size of seg_label. It has a attribute align_corners to control whether align_corners=True or False in "configs/base/models/stdc.py" line 71:

mmsegmentation/configs/_base_/models/stdc.py

Lines 61 to 72 in 4b905cb

	dict(
	type='STDCHead',
	in_channels=256,
	channels=64,
	num_convs=1,
	num_classes=2,
	boundary_threshold=0.1,
	in_index=0,
	norm_cfg=norm_cfg,
	concat_input=False,
	align_corners=False,
	loss_decode=[

But in code implementation, the align_corners is forced to True, ignoring the setting in configuration file, in line 87.

mmsegmentation/mmseg/models/decode_heads/stdc_head.py

Lines 83 to 89 in 4b905cb

	seg_logit = F.interpolate(
	seg_logit,
	boundary_targets.shape[2:],
	mode='bilinear',
	align_corners=True)
	loss = super(STDCHead, self).losses(seg_logit,
	boudary_targets_pyramid.long())

Bug fix
Actually STDCHead.losses calls BaseDecodeHead.losses(line 88-89), and BaseDecodeHead.losses will resize seg_logit to the same size of seg_label using configuration's setting align_corners(line 239).

mmsegmentation/mmseg/models/decode_heads/stdc_head.py

Lines 88 to 89 in 4b905cb

	loss = super(STDCHead, self).losses(seg_logit,
	boudary_targets_pyramid.long())

mmsegmentation/mmseg/models/decode_heads/decode_head.py

Lines 232 to 239 in 4b905cb

	def losses(self, seg_logit, seg_label):
	"""Compute segmentation loss."""
	loss = dict()
	seg_logit = resize(
	input=seg_logit,
	size=seg_label.shape[2:],
	mode='bilinear',
	align_corners=self.align_corners)

Therefore, there is no need to do interpolate in STDCHead.losses again. Just deleting the code block line 83-87 in "mmseg/models/decode_heads/stdc_head.py" fixes the bug.

[MengzhangLI]

Hi, thanks for your warm-hearted reminder. I would fix it asap.