## Description

I am currently trying to optimize SSDMobilenetV2 for inference speed on the Jetson TX2 by pruning anchor boxes that are not used by the classes in my dataset. The initial number of anchor boxes in the default implementation of SSDMobilenetV2 from the Tensorflow object detection zoo is 1917. And after pruning the number of boxes comes to 1885. Not a significant decrease but still I plan to do more optimizations later on and hence this info might be useful.

I am successfully able to convert the default SSDMobilenetV2 model to a TensorRT binary with the plugins provided by TensorRT, but I cannot convert the custom model. The compilation stops by throwing an aassertion error at line 246 of NMSPlugin.cpp. This is the line which checks the following:

ASSERT(numPriors * numLocClasses * nbBoxCoordinates == inputDims[param.inputOrder[0]].d[0]);

Printing the values of these variables for different input orders (given in ) I get,

```
pruned:[021] numPriors:0 numLocClasses:1 C1:2 C2:5655 C3:1
pruned:[012] numPriors:0 numLocClasses:1 C1:2 C2:7540 C3:1
pruned:[102] numPriors:0 numLocClasses:1 C1:7540 C2:2 C3:1
pruned:[120] numPriors:1917 numLocClasses:1 C1:7540 C2:5655 C3:7668
pruned:[201] numPriors:0 numLocClasses:1 C1:5655 C2:2 C3:1
pruned:[210] numPriors:1917 numLocClasses:1 C1:5655 C2:7540 C3:7668
```

The right value of numPriors should be 1885 (which is 7540/4). But I get 1917(which is 7668/4) which is the older number of boxes. **Why do I get the older value of anchor boxes here?**

I do not understand from where inputDims gets its values. Is this configurable?

## Environment

**TensorRT Version**: 7.1.0

**GPU Type**: PASCAL

**Nvidia Driver Version**:

**CUDA Version**: 10.2

**CUDNN Version**: 8.0

**Operating System + Version**: L4T from JetPack 4.4 DP

**Python Version (if applicable)**: 3.6.9

**TensorFlow Version (if applicable)**: 1.15.0

**PyTorch Version (if applicable)**:

**Baremetal or Container (if container which image + tag)**:

## Relevant Files

Please attach or include links to any models, data, files, or scripts necessary to reproduce your issue. (Github repo, Google Drive, Dropbox, etc.)

## Steps To Reproduce

Please include:

- Exact steps/commands to build your repro
- Exact steps/commands to run your repro
- Full traceback of errors encountered

**Log when using trtexec:**

`... [08/09/2020-15:57:13] [V] [TRT] Plugin creator registration succeeded - ::Split [08/09/2020-15:57:13] [V] [TRT] Plugin creator registration succeeded - ::SpecialSlice_TRT [08/09/2020-15:57:13] [V] [TRT] Plugin creator registration succeeded - ::InstanceNormalization_TRT [08/09/2020-15:57:14] [V] [TRT] UFFParser: Parsing MultipleGridAnchorGenerator[Op: _GridAnchor_TRT]. [08/09/2020-15:57:14] [V] [TRT] UFFParser: Parsing concat_priorbox[Op: Concat]. Inputs: MultipleGridAnchorGenerator [08/09/2020-15:57:14] [V] [TRT] UFFParser: concat_priorbox -> [2,7668,1] [08/09/2020-15:57:14] [V] [TRT] UFFParser: Applying order forwarding to: concat_priorbox [08/09/2020-15:57:14] [V] [TRT] UFFParser: Parsing Input[Op: Input]. [08/09/2020-15:57:14] [V] [TRT] UFFParser: Input -> [1,3,300,300] [08/09/2020-15:57:14] [V] [TRT] UFFParser: Applying order forwarding to: Input [08/09/2020-15:57:14] [V] [TRT] UFFParser: Parsing FeatureExtractor/MobilenetV2/Conv/weights[Op: Const]. [08/09/2020-15:57:14] [V] [TRT] UFFParser: FeatureExtractor/MobilenetV2/Conv/weights -> [3,3,3,32] [08/09/2020-15:57:14] [V] [TRT] UFFParser: Applying order forwarding to: FeatureExtractor/MobilenetV2/Conv/weights [08/09/2020-15:57:14] [V] [TRT] UFFParser: Parsing FeatureExtractor/MobilenetV2/Conv/Conv2D[Op: Conv]. Inputs: Input, FeatureExtractor/MobilenetV2/Conv/weights [08/09/2020-15:57:14] [V] [TRT] UFFParser: Inserting transposes for FeatureExtractor/MobilenetV2/Conv/Conv2D [08/09/2020-15:57:14] [E] [TRT] UffParser: Parser error: FeatureExtractor/MobilenetV2/Conv/Conv2D: Order size is not matching the number dimensions of TensorRT [08/09/2020-15:57:14] [E] Failed to parse uff file [08/09/2020-15:57:14] [E] Parsing model failed [08/09/2020-15:57:14] [E] Engine creation failed [08/09/2020-15:57:14] [E] Engine set up failed &&&& FAILED TensorRT.trtexec # /usr/src/tensorrt/bin/trtexec --uff=tmp_v2_coco.uff --uffInput=image_tensor:0,3,300,300 --output=NMS:0 --fp16 --verbose --saveEngine=trt.bin`

**Log using build_engine.py:**

python build_engine.py

…

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_13/expand/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_13/expand/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x64_relu_interior_nn_v1

[TensorRT] VERBOSE: BoxPredictor_0/ClassPredictor/Conv2D || BoxPredictor_0/BoxEncodingPredictor/Conv2D (hcudnn_winograd) Set Tactic Name: maxwell_fp16x2_hcudnn_winograd_fp16x2_128x128_ldg1_ldg4_relu_tile148m_nt_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_13/project/Conv2D (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_14/expand/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_14/expand/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_14/project/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_14/add (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_15/expand/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_15/expand/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_15/project/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_15/add (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_16/expand/Conv2D + FeatureExtractor/MobilenetV2/expanded_conv_16/expand/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/expanded_conv_16/project/Conv2D (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x64_relu_interior_nn_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/Conv_1/Conv2D + FeatureExtractor/MobilenetV2/Conv_1/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x128_relu_interior_nn_v1

[TensorRT] VERBOSE: BoxPredictor_1/ClassPredictor/Conv2D || BoxPredictor_1/BoxEncodingPredictor/Conv2D (hcudnn_winograd) Set Tactic Name: maxwell_fp16x2_hcudnn_winograd_fp16x2_128x128_ldg1_ldg4_relu_tile148m_nt_v1

[TensorRT] VERBOSE: FeatureExtractor/MobilenetV2/layer_19_1_Conv2d_2_1x1_256/Conv2D + FeatureExtractor/MobilenetV2/layer_19_1_Conv2d_2_1x1_256/Relu6 (hcudnn) Set Tactic Name: maxwell_fp16x2_hcudnn_fp16x2_128x64_relu_interior_nn_v1

#assertionnmsPlugin.cpp,246

Aborted (core dumped)