vis4d.op.box.poolers

Init sampler module.

class MultiScaleRoIAlign(sampling_ratio, *args, **kwargs)

RoI Align supporting multi-scale inputs.

Creates an instance of the class.

class MultiScaleRoIPool(resolution, strides, canonical_box_size=224, canonical_level=4, aligned=True)

RoI Pool supporting multi-scale inputs.

Multi-scale version of arbitrary RoI pooling operations.

Parameters:

• resolution (tuple[int, int]) – Pooler resolution.

• strides (list[int]) – Feature map strides relative to the input. The strides must be powers of 2 and a monotically decreasing geometric sequence with a factor of 1/2.

• canonical_box_size (int) – Canonical box size in pixels (sqrt(box area)). The default is heuristically defined as 224 pixels in the FPN paper (based on ImageNet pre-training).

• canonical_level (int) – The feature map level index from which a canonical sized box should be placed. The default is defined as level 4 (stride=16) in the FPN paper, i.e., a box of size 224x224 will be placed on the feature with stride=16. The box placement for all boxes will be determined from their sizes w.r.t canonical_box_size. For example, a box whose area is 4x that of a canonical box should be used to pool features from feature level canonical_level+1.

• aligned (bool) – For roi_align op. Shift the box coordinates it by -0.5 for a better alignment with the two neighboring pixel indices.

class RoIPooler(resolution)

Base class for RoI poolers.

Creates an instance of the class.

abstract forward(features, boxes)

Pool features in input bounding boxes from given feature maps.

Return type:

Tensor

Modules

vis4d.op.box.poolers.base	RoI Pooling module base.
vis4d.op.box.poolers.roi_pooler	Vis4D RoI Pooling module.
vis4d.op.box.poolers.utils	Utility functions for RoI poolers.