IKeypointSelector
This module selects keypoint given current frame and (optionally) estimated depth, depth_cov, and flow_cov.
The selector also receives an argument numPoint
as hint to how many keypoints to select.
The numPoint
hint may not be followed strictly by the selector. Number of keypoint will fluctuate based on different selection strategy and the input conditions.
Keypoints in this codebase are always arranged in (u, v) format. This means that you need to output the index of keypoints in different coordinate system as pytorch. Use image[kp[..., 1], kp[..., 0]]
to read value of image on all u-v coords of keypoints.
Interface
class IKeypointSelector(ABC, ConfigTestableSubclass):
@abstractmethod
def select_point(
self,
frame: SourceDataFrame,
numPoint: int,
depth_map: torch.Tensor | None,
depth_cov_map: torch.Tensor | None,
flow_cov_map: torch.Tensor | None,
) -> torch.Tensor:
...
Methods to Implement
-
IKeypointSelector.select_point
Select keypoint for tracking using given frame, (optionally) estimated depth, depth_cov, and flow_cov. Return keypoint as a
torch.Tensor
withdtype=torch.float
and shape (N, 2) where keypoints are arranged in (u, v) format.
Implemenations
-
class SelectorCompose(IKeypointSelector)
A higher-order module that combines multiple
IKeypointSelector
instances with a relative weight. This module distribute keypoint selection to all "sub-selectors" according to the provided weight on everyselect_point
call.warningThe distribution of keypoint selection is achieved by estimating and setting
numPoint
for each selector included. Therefore, it might not be an accurate split, and the module makes no guarantee to the number of keypoints selected. -
class RandomSelector(IKeypointSelector)
Uniformly random select keypoints within the scope of [mask_width : -mask_width].
mask_width
is the width of image border that we don't want to select keypoint from. -
class GradientSelector(IKeypointSelector)
Select keypoint based on gradient information. Will random select points with sufficiently large local image gradient (calculated by Sobel filter).
-
class SparseGradienSelector(IKeypointSelector)
Select keypoint based on gradient information. Will random select points with sufficiently large local image gradient (calculated by Sobel filter).
Ensured sparsity of keypoint by applying non-maximum suppresion (NMS) on image gradient of keypoint candidates.
-
class GridSelector(IKeypointSelector)
Select keypoint following the grid - strictly uniform across the entire image.
The requested
numPoint
will be used to estimate the spacing between keypoints, but the selector may not generate exactlynumPoint
amount of keypoints.infoThis selector is deterministic and is used for internal benchmarking when we want reproducible results.
-
class CovAwareSelector(IKeypointSelector)
The keypoint selector used by the MAC-VO.
Selecting keypoints based on estimated depth, depth_cov, and flow_cov. See sect III.B of paper for detail.
-
class CovAwareSelector_NoDepth(IKeypointSelector)
Selecting keypoints based on estimated flow_cov.
The main difference with CovAwareSelector is dropping filters related with depth (i.e.
max_depth
anddepth_cov
).