plugin/multilevelProposeROI/README.md
This plugin is deprecated since TensorRT 10.12 and will be removed in a future release. No alternatives are planned to be provided.
Table Of Contents
The MultilevelProposeROI plugin generates the first-stage detection (ROI candidates) from the scores, refinement information from RPN(Region Proposal Network) and pre-defined anchors. It is
used in sampleMaskRCNN.
This plugin supports the NCHW format. It takes two input tensors: object_score and object_delta
object_score is the objectness score from RPN. object_score's shape is [N, anchors, 2, 1] where N is the batch_size, anchors is the total number of anchors and 2 means 2
classes of objectness --- foreground and background .
object_delta is the refinement information from RPN of shape [N, anchors, 4, 1]. 4 means 4 elements of refinement information --- [dy, dx, dh, dw]
This plugin generates one output tensor of shape [N, keep_topk, 4] where keep_topk is the maximum number of detections left after NMS and 4 means coordinates of ROI
candidates [y1, x1, y2, x2]
Instead of fed as input in Keras, the default anchors used in this plugin are generated upon initialization.
For resnet50 + 832*1344 input shape, the number of anchors can be computed as
Anchors in feature map P2: 208*336*3
Anchors in feature map P3: 104*168*3
Anchors in feature map P4: 52*84*3
Anchors in feature map P5: 26*42*3
Anchors in feature map P6(maxpooling): 13*21*3
This plugin has the plugin creator class MultilevelProposeROIPluginCreator and the plugin class MultilevelProposeROI.
The following parameters were used to create MultilevelProposeROI instance:
| Type | Parameter | Description |
|---|---|---|
int | prenms_topk | The number of ROIs which will be kept before NMS. |
int | keep_topk | Number of detections will be kept after NMS. |
float | iou_threshold | IOU threshold value used in NMS. |
int[3] | image_size | Input image shape in CHW. Defaults to [3, 832, 1344] |
The attribute prenms_topk is capped at 4096 to support embedded devices with smaller shared memory capacity.
To enable support for a device with higher memory, calls to sortPerClass, PerClassNMS and KeepTopKGatherBoxScore can be modified in MultilevelPropose (maskRCNNKernels.cu).
For terms and conditions for use, reproduction, and distribution, see the TensorRT Software License Agreement documentation.
May 2025 Add deprecation note.
January 2022: The Limitations section was added to this README.md file to document limitations of the plugin related to the maximum number of anchors it can support.
June 2020: This is the first release of this README.md file.
There are no known issues in this plugin.