wehub-resource-sync
84 lines
3.5 KiB
Markdown
84 lines
3.5 KiB
Markdown
# MultilevelProposeROI Plugin [DEPRECATED]
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**This plugin is deprecated since TensorRT 10.12 and will be removed in a future release. No alternatives are planned to be provided.**
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**Table Of Contents**
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- [Description](#description)
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* [Structure](#structure)
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- [Parameters](#parameters)
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- [Additional resources](#additional-resources)
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- [License](#license)
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- [Changelog](#changelog)
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- [Known issues](#known-issues)
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## Description
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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
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used in sampleMaskRCNN.
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### Structure
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This plugin supports the NCHW format. It takes two input tensors: `object_score` and `object_delta`
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`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
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classes of objectness --- foreground and background .
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`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]`
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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
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candidates `[y1, x1, y2, x2]`
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Instead of fed as input in Keras, the default anchors used in this plugin are generated upon `initialization`.
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For resnet50 + 832*1344 input shape, the number of anchors can be computed as
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```
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Anchors in feature map P2: 208*336*3
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Anchors in feature map P3: 104*168*3
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Anchors in feature map P4: 52*84*3
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Anchors in feature map P5: 26*42*3
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Anchors in feature map P6(maxpooling): 13*21*3
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```
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## Parameters
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This plugin has the plugin creator class `MultilevelProposeROIPluginCreator` and the plugin class `MultilevelProposeROI`.
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The following parameters were used to create `MultilevelProposeROI` instance:
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| Type | Parameter | Description
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|-------------------|----------------------------------|--------------------------------------------------------
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|`int` |`prenms_topk` |The number of ROIs which will be kept before NMS.
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|`int` |`keep_topk` |Number of detections will be kept after NMS.
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|`float` |`iou_threshold` |IOU threshold value used in NMS.
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|`int[3]` |`image_size` |Input image shape in CHW. Defaults to [3, 832, 1344]
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## Limitations
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The attribute `prenms_topk` is capped at 4096 to support embedded devices with smaller shared memory capacity.
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To enable support for a device with higher memory, calls to `sortPerClass`, `PerClassNMS` and `KeepTopKGatherBoxScore` can be modified in `MultilevelPropose` ([maskRCNNKernels.cu](https://github.com/NVIDIA/TensorRT/blob/main/plugin/common/kernels/maskRCNNKernels.cu)).
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## Additional resources
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## License
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For terms and conditions for use, reproduction, and distribution, see the [TensorRT Software License Agreement](https://docs.nvidia.com/deeplearning/sdk/tensorrt-sla/index.html)
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documentation.
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## Changelog
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May 2025
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Add deprecation note.
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January 2022: The [Limitations](#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.
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June 2020: This is the first release of this `README.md` file.
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## Known issues
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There are no known issues in this plugin.
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