some concepts that not appear at paper

[ShinoSpace]

hello! thanks for your great works!

when i go into source code, i found "sweep", "ida" and "bda". these maybe something we have not seen in LSS. can you kindly explain the meaning of the three concepts? thanks!

--- update ---

sorry for my not familiar with nuscenes data. i google and found sweep images are not annotated intermediate frames (the counterpart of annotated keyframe). maybe the first sweep image (index 0 of sweep axis) in your code is keyframe. is that correct? but i still not know about "ida" and "bda". hope you can kindly make some explanation for them. thanks!

for example in LSSFPN

def forward(self,
                sweep_imgs,
                mats_dict,
                timestamps=None,
                is_return_depth=False):
        """Forward function.

        Args:
            sweep_imgs(Tensor): Input images with shape of (B, num_sweeps,
                num_cameras, 3, H, W).
            mats_dict(dict):
                # ...
                ida_mats(Tensor): Transformation matrix for ida with
                    shape of (B, num_sweeps, num_cameras, 4, 4).
                # ...
                bda_mat(Tensor): Rotation matrix for bda with shape
                    of (B, 4, 4).
            # ...
        """
        batch_size, num_sweeps, num_cams, num_channels, img_height, \
            img_width = sweep_imgs.shape
        # ... ...

[yinchimaoliang]

Hello! ida represents image data augmentation and bda represents bev data augmentation.

[ww249]

Is there more detailed explanation about ida and bda?