YOLOv3

YOLOv3 is an object detection model that is included in the Transfer Learning Toolkit. YOLOv3 supports the following tasks:

• kmeans

• train

• evaluate

• inference

• prune

• export

These tasks can be invoked from the TLT launcher using the following convention on the command line:

            

            
tlt yolo_v3 <sub_task> <args_per_subtask>
        

where args_per_subtask are the command line arguments required for a given subtask. Each subtask is explained in detail below.

Below is a sample for the YOLOv3 spec file. It has six major components: yolov3_config, training_config, eval_config, nms_config, augmentation_config, and dataset_config. The format of the spec file is a protobuf text (prototxt) message and each of its fields can be either a basic data type or a nested message. The top level structure of the spec file is summarized in the table below.

            

            
random_seed: 42
yolov3_config {
  big_anchor_shape: "[(116,90), (156,198), (373,326)]"
  mid_anchor_shape: "[(30,61), (62,45), (59,119)]"
  small_anchor_shape: "[(10,13), (16,30), (33,23)]"
  matching_neutral_box_iou: 0.5
  arch: "darknet"
  nlayers: 53
  arch_conv_blocks: 2
  loss_loc_weight: 0.8
  loss_neg_obj_weights: 100.0
  loss_class_weights: 1.0
  freeze_bn: false
  freeze_blocks: 0
  freeze_blocks: 1
  force_relu: false
}
training_config {
  batch_size_per_gpu: 16
  checkpoint_interval: 10
  num_epochs: 80
  enable_qat: false
  learning_rate {
    soft_start_annealing_schedule {
      min_learning_rate: 5e-5
      max_learning_rate: 2e-2
      soft_start: 0.15
      annealing: 0.8
    }
  }
  regularizer {
    type: L1
    weight: 3e-5
  }
  optimizer {
    adam {
      epsilon: 1e-7
      beta1: 0.9
      beta2: 0.999
      amsgrad: false
    }
  }
  pretrain_model_path: "EXPERIMENT_DIR/darknet_53.hdf5"
}
eval_config {
  average_precision_mode: SAMPLE
  batch_size: 16
  matching_iou_threshold: 0.5
}
nms_config {
  confidence_threshold: 0.01
  clustering_iou_threshold: 0.6
  top_k: 200
}
augmentation_config {
  hue: 0.1
  saturation: 1.5
  exposure:1.5
  vertical_flip:0
  horizontal_flip: 0.5
  jitter: 0.3
  output_width: 1248
  output_height: 384
  output_channel: 3
  randomize_input_shape_period: 0
  image_mean {
    key: 'b'
    value: 103.9
  }
  image_mean {
    key: 'g'
    value: 116.8
  }
  image_mean {
    key: 'r'
    value: 123.7
  }
}
dataset_config {
  data_sources: {
      label_directory_path: "/workspace/tlt-experiments/data/training/label_2"
      image_directory_path: "/workspace/tlt-experiments/data/training/image_2"
  }
  include_difficult_in_training: true
  target_class_mapping {
      key: "car"
      value: "car"
  }
  target_class_mapping {
      key: "pedestrian"
      value: "pedestrian"
  }
  target_class_mapping {
      key: "cyclist"
      value: "cyclist"
  }
  target_class_mapping {
      key: "van"
      value: "car"
  }
  target_class_mapping {
      key: "person_sitting"
      value: "pedestrian"
  }
  validation_data_sources: {
      label_directory_path: "/workspace/tlt-experiments/data/val/label"
      image_directory_path: "/workspace/tlt-experiments/data/val/image"
  }
}
        

Training Config

The training configuration (training_config) defines the parameters needed for the training, evaluation and inference. Details are summarized in the table below.

Evaluation Config

The evaluation configuration (eval_config) defines the parameters needed for evaluation either during training or as a standalone procedure. Details are summarized in the table below.

NMS Config

The NMS configuration (nms_config) defines the parameters needed for the NMS postprocessing. NMS config applies to the NMS layer of the model in training, validation, evaluation, inference and export. Details are summarized in the table below.

Augmentation Config

The augmentation configuration (augmentation_config) defines the parameters needed for online data augmentation. Details are summarized in the table below.

Dataset Config

The following is an example dataset_config element:

            

            
dataset_config {
   data_sources: {
       label_directory_path: "/workspace/tlt-experiments/data/training/label_2"
       image_directory_path: "/workspace/tlt-experiments/data/training/image_2"
   }
   data_sources: {
       label_directory_path: "/workspace/tlt-experiments/data/training/label_3"
       image_directory_path: "/workspace/tlt-experiments/data/training/image_3"
   }
   include_difficult_in_training: true
   target_class_mapping {
       key: "car"
       value: "car"
   }
   target_class_mapping {
       key: "pedestrian"
       value: "pedestrian"
   }
   target_class_mapping {
       key: "cyclist"
       value: "cyclist"
   }
   target_class_mapping {
       key: "van"
       value: "car"
   }
   target_class_mapping {
       key: "person_sitting"
       value: "pedestrian"
   }
   validation_data_sources: {
       label_directory_path: "/workspace/tlt-experiments/data/val/label_1"
       image_directory_path: "/workspace/tlt-experiments/data/val/image_1"
   }
}
        

The YOLOv3 dataloader assumes the training/validation split is already done and data is prepared in KITTI format: images and labels are in two separate folders and each image file has a corresponding txt label file in the label folder with the same filename. The label file content should also follow KITTI format.

The parameters in dataset_config are defined as follows:

• data_sources: Captures the path to datasets to train on. If you have multiple data sources for training, you may use multiple data_sources. This field contains 2 parameters:

  • label_directory_path: Path to the data source label folder

  • image_directory_path: Path to the data source image folder

• include_difficult_in_training: Specifies whether to include difficult boxes in training. If set to False, difficult boxes will be ignored. Difficult boxes are those with occlusion level 2 in KITTI labels.

• target_class_mapping: This parameter maps the class names in the labels to the target class to be trained in the network. An element is defined for every source class to target class mapping. This field is included with the intention of grouping similar class objects under one umbrella. For example, “car”, “van”, “heavy_truck”, etc. may be grouped under “automobile”. The “key” field is the value of the class name in the tfrecords file, and the “value” field corresponds to the value that the network is expected to learn.

• validation_data_sources: Captures the path to datasets to validate on. If you have multiple data sources for validation, you may use multiple validation_data_sources. Like data_sources, this field contains two parameters.

YOLOv3 Config

The YOLOv3 configuration (yolov3_config) defines the parameters needed for building the YOLOv3 model. Details are summarized in the table below.

The anchor shape should match most ground truth boxes in the dataset to help the network learn bounding boxes. You can use the kmeans algorithm to generate the anchor shapes. The algorithm is implemented in TLT as the tlt yolo_v3 kmeans command. You can use the output of the algorithm as the anchor shape in the yolov3_config spec file.

            

            
tlt yolo_v3 kmeans [-h] -l <label_folders>
                        -i <image_folders>
                        -x <network base input width>
                        -y <network base input height>
                        [-n <num_clusters>]
                        [--max_steps <kmeans max steps>]
                        [--min_x <ignore boxes with width less than this value>]
                        [--min_y <ignore boxes with height less than this value>]
        

Required Arguments

• -l: The paths to the training label folders. Multiple folder paths should be separated with spaces.

• -i: The paths to corresponding training image folders. Folder counts and orders must match label folders.

• -x: The base network input width, which should be output_width in the augmentation config section of your spec file.

• -y: The base network input height, which should be output_height in the augmentation config section of your spec file.

Optional Arguments

• -n: The number of shape clusters. This defines how many shape centers the command will output. The default is 9 (3 per group, with 3 groups)

• --max_steps: The maximum number of steps the kmeans algorithm should run. If the algorithm does not converge at this step, a suboptimal result will be returned. The default value is 10000.

• --min_x: Ignore ground-truth boxes with width less than this value in the reshaped image (images are first reshaped to the network base shape as -x, -y)

• --min_y: Ignore ground-truth boxes with height less than this value in the reshaped image (images are first reshaped to the network base shape as -x, -y)

• -h, --help: Show this help message and exit.

Train the YOLOv3 model using this command:

            

            
tlt yolo_v3 train [-h] -e <experiment_spec>
                       -r <output_dir>
                       -k <key>
                       [--gpus <num_gpus>]
                       [--gpu_index <gpu_index>]
                       [--use_amp]
                       [--log_file <log_file_path>]
        

Required Arguments

• -r, --results_dir: Path to the folder where the experiment output is written.

• -k, --key: Provide the encryption key to decrypt the model.

• -e, --experiment_spec_file: Experiment specification file to set up the evaluation experiment. This should be the same as the training specification file.

Optional Arguments

• --gpus: The number of GPUs to be used for training in a multi-GPU scenario (the default value is 1).

• --gpu_index: The GPU indices used to run training. You can use GPU indicies to specify the GPU(s) to use for training when the machine has multiple GPUs installed.

• --use_amp: A flag to enable AMP training.

• --log_file: The path to the log file. The default path is “stdout”.

• -h, --help: Show this help message and exit.

Input Requirement

• Input size: C * W * H (where C = 1 or 3, W >= 128, H >= 128, W, H are multiples of 32)

• Image format: JPG, JPEG, PNG

• Label format: KITTI detection

Sample Usage

Here’s an example of using the train command on a YOLOv3 model:

            

            
tlt yolo_v3 train --gpus 2 -e /path/to/spec.txt -r /path/to/result -k $KEY
        

To run evaluation for a YOLOv3 model use this command:

            

            
tlt yolo_v3 evaluate [-h] -e <experiment_spec_file>
                          -m <model_file>
                          -k <key>
                          [--gpu_index <gpu_index>]
                          [--log_file <log_file_path>]
        

Required Arguments

• -e, --experiment_spec_file: Experiment spec file to set up the evaluation experiment. This should be the same as the training specification file.

• -m, --model: Path to the model file to use for evaluation. Model can be either .tlt model file or TensorRT engine.

• -k, --key: Provide the key to load the model (not needed if model is a TensorRT engine).

Optional Arguments

• -h, --help: show this help message and exit.

• --gpu_index: The GPU index used to run the evaluation. We can specify the GPU index used to run evaluation when the machine has multiple GPUs installed. Note that evaluation can only run on a single GPU.

• --log_file: Path to the log file. Defaults to stdout.

The inference tool for YOLOv3 networks may be used to visualize bboxes or generate frame-by-frame KITTI-format labels on a single image or a directory of images. An example of the command for this tool is shown here:

            

            
tlt yolo_v3 inference [-h] -i <input directory>
                           -o <output annotated image directory>
                           -e <experiment spec file>
                           -m <model file>
                           -k <key>
                           [-l <output label directory>]
                           [-t <visualization threshold>]
                           [--gpu_index <gpu_index>]
                           [--log_file <log_file_path>]
        

Required Arguments

• -m, --model: Path to the trained model (TLT model) or TensorRT engine.

• -i, --in_image_dir: The directory of input images for inference.

• -o, --out_image_dir: The directory path to output annotated images.

• -k, --key: Key to load model (not needed if model is a TensorRT engine).

• -e, --config_path: Path to an experiment spec file for training.

Optional Arguments

• -t, --draw_conf_thres: The threshold for drawing a bbox. The default value is 0.3.

• -h, --help: Show this help message and exit.

• -l, --out_label_dir: The directory to output KITTI labels.

• --gpu_index: The GPU index used to run inference. You can specify the index of the GPU to run evaluation when the machine has multiple GPUs installed. Note that evaluation can only run on a single GPU.

• --log_file: The path to the log file. The default path is “stdout”.

Pruning removes parameters from the model to reduce the model size without compromising the integrity of the model itself using the tlt yolo_v3 prune command.

The tlt yolo_v3 prune command includes these parameters:

            

            
tlt yolo_v3 prune [-h] -m <pretrained_model>
                       -o <output_file>
                       -k <key>
                       [-n <normalizer>]
                       [-eq <equalization_criterion>]
                       [-pg <pruning_granularity>]
                       [-pth <pruning threshold>]
                       [-nf <min_num_filters>]
                       [-el [<excluded_list>]
        

Required Arguments

• -m, --model: Path to pretrained YOLOv3 model.

• -o, --output_file: Path to output checkpoints.

• -k, --key: Key to load a .tlt model.

Optional Arguments

• -h, --help: Show this help message and exit.

• -n, –normalizer: max to normalize by dividing each norm by the maximum norm within a layer; L2 to normalize by dividing by the L2 norm of the vector comprising all kernel norms. (default: max)

• -eq, --equalization_criterion: Criteria to equalize the stats of inputs to an element wise op layer, or depth-wise convolutional layer. This parameter is useful for resnets and mobilenets. Options are arithmetic_mean,:code:geometric_mean, union, and intersection. (default: union)

• -pg, -pruning_granularity: Number of filters to remove at a time (default:8)

• -pth: Threshold to compare normalized norm against (default:0.1)

• -nf, --min_num_filters: Minimum number of filters to keep per layer (default:16).

• -el, --excluded_layers: List of excluded_layers. Examples: -i item1 item2 (default: []).

After pruning, the model needs to be retrained. See Re-training the Pruned Model for more details.

Using the Prune Command

Here’s an example of using the tlt yolo_v3 prune command:

            

            
tlt yolo_v3 prune -m /workspace/output/weights/resnet_003.tlt \
                  -o /workspace/output/weights/resnet_003_pruned.tlt \
                  -eq union \
                  -pth 0.7 -k $KEY
        

Once the model has been pruned, there might be a slight decrease in accuracy because some previously useful weights may be removed. To regain accuracy, NVIDIA recommends that you retrain this pruned model over the same dataset. To do this, use the tlt yolo_v3 train command as documented in Training the model, with an updated spec file that points to the newly pruned model as the pruned_model_path.

We recommend turning off the regularizer in the training_config for detectnet to recover the accuracy when retraining a pruned model. To do this, set the regularizer type to NO_REG as mentioned Training config. All the other parameters may be retained in the spec file from the previous training.

Exporting the model decouples the training process from inference and allows conversion to TensorRT engines outside the TLT environment. TensorRT engines are specific to each hardware configuration and should be generated for each unique inference environment. The exported model may be used universally across training and deployment hardware.

The exported model format is referred to as .etlt. Like the .tlt model format, .etlt is an encrypted model format, and it uses the same key as the .tlt model that it is exported from. This key is required when deploying this model.

INT8 Mode Overview

TensorRT engines can be generated in INT8 mode to improve performance but require a calibration cache at engine creation-time. The calibration cache is generated using a calibration tensor file, if tlt yolo_v3 export is run with the --data_type flag set to int8. Pre-generating the calibration information and caching it removes the need for calibrating the model on the inference machine. Moving the calibration cache is usually much more convenient than moving the calibration tensorfile, since it is a much smaller file and can be moved with the exported model. Using the calibration cache also speeds up engine creation as building the cache can take several minutes to generate depending on the size of the Tensorfile and the model itself.

The export tool can generate the INT8 calibration cache by ingesting training data using one of these options:

• Option 1: Using the training data loader to load the training images for INT8 calibration. This option is now the recommended approach to support multiple image directories by leveraging the training dataset loader. This also ensures two important aspects of data during calibration:

  • Data pre-processing in the INT8 calibration step is the same as in the training process.

  • The data batches are sampled randomly across the entire training dataset, thereby improving the accuracy of the INT8 model.

• Option 2: Pointing the tool to a directory of images that you want to use to calibrate the model. For this option, make sure to create a sub-sampled directory of random images that best represent your training dataset.

FP16/FP32 Model

The calibration.bin is only required if you need to run inference at INT8 precision. For FP16/FP32-based inference, the export step is much simpler. All you need to do is provide a .tlt model from the training/retraining step to be converted into .etlt format.

Exporting the Model

Here’s an example of the command line arguments of the tlt yolo_v3 export command:

            

            
tlt yolo_v3 export [-h]
                    -m <path to the .tlt model file generated by tlt train>
                    -k <key>
                    [-o <path to output file>]
                    [--cal_data_file <path to tensor file>]
                    [--cal_image_dir <path to the directory images to calibrate the model]
                    [--cal_cache_file <path to output calibration file>]
                    [--data_type <Data type for the TensorRT backend during export>]
                    [--batches <Number of batches to calibrate over>]
                    [--max_batch_size <maximum trt batch size>]
                    [--max_workspace_size <maximum workspace size]
                    [--batch_size <batch size to TensorRT engine>]
                    [--experiment_spec <path to experiment spec file>]
                    [--engine_file <path to the TensorRT engine file>]
                    [--gen_ds_config]
                    [--verbose]
                    [--strict_type_constraints]
                    [--force_ptq]
                    [--gpu_index <gpu_index>]
                    [--log_file <log_file_path>]
        

Required Arguments

• -m, --model: The path to the .tlt model file to be exported.

• -k, --key: The key used to save the .tlt model file.

• -e, --experiment_spec: The path to the spec file.

Optional Arguments

• -h, --help: Show this help message and exit.

• -o, --output_file: The path to save the exported model to. The default path is ./<input_file>.etlt.

• --data_type: The desired engine data type. The options are fp32, fp16, int8. The default value is fp32. A calibration cache will be generated in INT8 mode. If using INT8, the following INT8 arguments are required.

• --gen_ds_config: A Boolean flag indicating whether to generate the template DeepStream related configuration (“nvinfer_config.txt”) as well as a label file (“labels.txt”) in the same directory as the output_file. Note that the config file is NOT a complete configuration file and requires the user to update the sample config files in DeepStream with the parameters generated.

• -s, --strict_type_constraints: A Boolean flag indicating whether to apply the TensorRT strict type constraints when building the TensorRT engine.

• --gpu_index: The index of (discrete) GPUs used for exporting the model. You can specify the index of the GPU to run export if the machine has multiple GPUs installed. Note that export can only run on a single GPU.

• --log_file: The path to the log file. The default path is “stdout”.

INT8 Export Mode Required Arguments

• --cal_data_file: tensorfile generated for calibrating the engine. This can also be an output file if used with --cal_image_dir.

• --cal_image_dir: Directory of images to use for calibration.

INT8 Export Optional Arguments

• --cal_cache_file: The path to save the calibration cache file to. The default value is ./cal.bin.

• --batches: Number of batches to use for calibration and inference testing.The default value is 10.

• --batch_size: Batch size to use for calibration. The default value is 8.

• --max_batch_size: Maximum batch size of TensorRT engine. The default value is 16.

• --max_workspace_size: Maximum workspace size of TensorRT engine. The default value is: 1073741824 = 1<<30).

• --engine_file: Path to the serialized TensorRT engine file. Note that this file is hardware specific, and cannot be generalized across GPUs. Useful to quickly test your model accuracy using TensorRT on the host. As TensorRT engine file is hardware specific, you cannot use this engine file for deployment unless the deployment GPU is identical to training GPU.

• --force_ptq: A boolean flag to force post training quantization on the exported etlt model.

Sample Usage

Here’s a sample command to export a YOLOv3 model in INT8 mode:

            

            
tlt yolo_v3 export -m /workspace/yolov3_resnet18_epoch_100.tlt  \
                         -o /workspace/yolov3_resnet18_epoch_100_int8.etlt \
                         -e /workspace/yolov3_retrain_resnet18_kitti.txt \
                         -k $KEY \
                         --cal_image_dir /workspace/data/training/image_2 \
                         --data_type int8 \
                         --batch_size 8 \
                         --batches 10 \
                         --cal_cache_file /export/cal.bin  \
                         --cal_data_file /export/cal.tensorfile
        

The deep learning and computer vision models that you’ve trained can be deployed on edge devices, such as a Jetson Xavier or Jetson Nano, a discrete GPU, or in the cloud with NVIDIA GPUs. TLT has been designed to integrate with DeepStream SDK, so models trained with TLT will work out of the box with DeepStream SDK.

DeepStream SDK is a streaming analytic toolkit to accelerate building AI-based video analytic applications. This section will describe how to deploy your trained model to DeepStream SDK.

To deploy a model trained by TLT to DeepStream we have two options:

• Option 1: Integrate the .etlt model directly in the DeepStream app. The model file is generated by export.

• Option 2: Generate a device specific optimized TensorRT engine using tlt-converter. The generated TensorRT engine file can also be ingested by DeepStream.

Machine-specific optimizations are done as part of the engine creation process, so a distinct engine should be generated for each environment and hardware configuration. If the TensorRT or CUDA libraries of the inference environment are updated (including minor version updates), or if a new model is generated, new engines need to be generated. Running an engine that was generated with a different version of TensorRT and CUDA is not supported and will cause unknown behavior that affects inference speed, accuracy, and stability, or it may fail to run altogether.

Option 1 is very straightforward. The .etlt file and calibration cache are directly used by DeepStream. DeepStream will automatically generate the TensorRT engine file and then run inference. TensorRT engine generation can take some time depending on size of the model and type of hardware. Engine generation can be done ahead of time with Option 2. With option 2, the tlt-converter is used to convert the .etlt file to TensorRT; this file is then provided directly to DeepStream.

See the Exporting the Model section for more details on how to export a TLT model.

TensorRT Open Source Software (OSS)

For YOLOv3, we need the batchTilePlugin and batchedNMSPlugin plugins from the TensorRT OSS build.

If the deployment platform is x86 with an NVIDIA GPU, follow the TensorRT OSS on x86 instructions. On the other hand, if your deployment is on the NVIDIA Jetson platform, follow the TensorRT OSS on Jetson (ARM64) instructions.

TensorRT OSS on x86

Building TensorRT OSS on x86:

1. Install Cmake (>=3.13).

   Note

   TensorRT OSS requires cmake version v3.13 or greater, so install cmake 3.13 if your cmake version is lower than 3.13c.

   Copy

   Copied!

               
   
               
   sudo apt remove --purge --auto-remove cmake
   wget https://github.com/Kitware/CMake/releases/download/v3.13.5/cmake-3.13.5.tar.gz
   tar xvf cmake-3.13.5.tar.gz
   cd cmake-3.13.5/
   ./configure
   make -j$(nproc)
   sudo make install
   sudo ln -s /usr/local/bin/cmake /usr/bin/cmake
           

   
   

2. Get your GPU architecture. The GPU_ARCHS value can be retrieved by the deviceQuery CUDA sample:

   Copy

   Copied!

               
   
               
   cd /usr/local/cuda/samples/1_Utilities/deviceQuery
   sudo make
   ./deviceQuery
           

   If the /usr/local/cuda/samples doesn’t exist in your system, you could download deviceQuery.cpp from this repo. Compile and run deviceQuery:

   Copy

   Copied!

               
   
               
   nvcc deviceQuery.cpp -o deviceQuery
   ./deviceQuery
           

   This command will output something like this, which indicates that the GPU_ARCHS is 75 based on the CUDA Capability major/minor version.

   Copy

   Copied!

               
   
               
   Detected 2 CUDA Capable device(s)
   
   Device 0: "Tesla T4"
     CUDA Driver Version / Runtime Version          10.2 / 10.2
     CUDA Capability Major/Minor version number:    7.5
           

3. Build TensorRT OSS:

   Copy

   Copied!

               
   
               
   git clone -b release/7.0 https://github.com/nvidia/TensorRT
   cd TensorRT/
   git submodule update --init --recursive
   export TRT_SOURCE=`pwd`
   cd $TRT_SOURCE
   mkdir -p build && cd build
           

   Note

   Make sure your GPU_ARCHS from step 2 is in TensorRT OSS CMakeLists.txt. If GPU_ARCHS is not in TensorRT OSS CMakeLists.txt, add -DGPU_ARCHS=<VER> as below, where <VER> represents the GPU_ARCHS from step 2.

   Copy

   Copied!

               
   
               
   /usr/local/bin/cmake .. -DGPU_ARCHS=xy  -DTRT_LIB_DIR=/usr/lib/aarch64-linux-gnu/ -DCMAKE_C_COMPILER=/usr/bin/gcc -DTRT_BIN_DIR=`pwd`/out
   make nvinfer_plugin -j$(nproc)
           

   After building ends successfully, libnvinfer_plugin.so* will be generated under \`pwd\`/out/.

4. Replace the original libnvinfer_plugin.so*:

   Copy

   Copied!

               
   
               
   sudo mv /usr/lib/x86_64-linux-gnu/libnvinfer_plugin.so.7.x.y ${HOME}/libnvinfer_plugin.so.7.x.y.bak   // backup original libnvinfer_plugin.so.x.y
   sudo cp $TRT_SOURCE/`pwd`/out/libnvinfer_plugin.so.7.m.n  /usr/lib/x86_64-linux-gnu/libnvinfer_plugin.so.7.x.y
   sudo ldconfig
           

TensorRT OSS on Jetson (ARM64)

1. Install Cmake (>=3.13)

   Note

   TensorRT OSS requires cmake version v3.13 or greater, while the default version of cmake on Jetson/Ubuntu 18.04 is cmake 3.10.2.

   Upgrade TensorRT OSS as follows:

   Copy

   Copied!

               
   
               
   sudo apt remove --purge --auto-remove cmake
   wget https://github.com/Kitware/CMake/releases/download/v3.13.5/cmake-3.13.5.tar.gz
   tar xvf cmake-3.13.5.tar.gz
   cd cmake-3.13.5/
   ./configure
   make -j$(nproc)
   sudo make install
   sudo ln -s /usr/local/bin/cmake /usr/bin/cmake
           

2. Get the GPU architecture for your platform. The GPU_ARCHS for different Jetson platforms are given in the following table:

   Jetson Platform	GPU_ARCHS
   Nano/Tx1	53
   Tx2	62
   AGX Xavier/Xavier NX	72

3. Build TensorRT OSS:

   Copy

   Copied!

               
   
               
   git clone -b release/7.0 https://github.com/nvidia/TensorRT
   cd TensorRT/
   git submodule update --init --recursive
   export TRT_SOURCE=`pwd`
   cd $TRT_SOURCE
   mkdir -p build && cd build
           

   Note

   The -DGPU_ARCHS=72 below is for Jetson Xavier or NX; for other Jetson platforms, change 72 to the GPU_ARCHS number shown in step 2.

   Copy

   Copied!

               
   
               
   /usr/local/bin/cmake .. -DGPU_ARCHS=72  -DTRT_LIB_DIR=/usr/lib/aarch64-linux-gnu/ -DCMAKE_C_COMPILER=/usr/bin/gcc -DTRT_BIN_DIR=`pwd`/out
   make nvinfer_plugin -j$(nproc)
           

   After building completes successfully, libnvinfer_plugin.so* will be generated under ‘pwd’/out/.

4. Replace "libnvinfer_plugin.so*" with the newly generated version:

   Copy

   Copied!

               
   
               
   sudo mv /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.x.y ${HOME}/libnvinfer_plugin.so.7.x.y.bak   // backup original libnvinfer_plugin.so.x.y
   sudo cp `pwd`/out/libnvinfer_plugin.so.7.m.n  /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.x.y
   sudo ldconfig
           

Generating an Engine Using tlt-converter

The tlt-converter tool is provided with the Transfer Learning Toolkit to facilitate the deployment of TLT trained models on TensorRT and/or Deepstream. This section elaborates on how to generate a TensorRT engine using tlt-converter.

For deployment platforms with an x86-based CPU and discrete GPUs, the tlt-converter is distributed within the TLT docker. Therefore, we suggest using the docker to generate the engine. However, this requires that the user adhere to the same minor version of TensorRT as distributed with the docker. The TLT docker includes TensorRT version 7.2.

Instructions for x86

1. Copy /opt/nvidia/tools/tlt-converter to the target machine.

2. Install TensorRT 7.0+ for the respective target machine.

3. For YOLOv3, you need to build TensorRT Open source software on the machine. Instructions to build TensorRT OSS on x86 can be found in TensorRT OSS on x86 section above or in this GitHub repo.

4. Run tlt-converter using the sample command below and generate the engine.

Instructions for Jetson

For the Jetson platform, the tlt-converter is available to download in the dev zone. Once the tlt-converter is downloaded, please follow the instructions below to generate a TensorRT engine.

1. Unzip tlt-converter-trt7.1.zip on the target machine.

2. Install the open ssl package using this command:

   Copy

   Copied!

               
   
               
   sudo apt-get install libssl-dev
           

3. Export the following environment variables:

            

            
$ export TRT_LIB_PATH=”/usr/lib/aarch64-linux-gnu”
$ export TRT_INC_PATH=”/usr/include/aarch64-linux-gnu”
        

4. For Jetson devices, TensorRT 7.1 comes pre-installed with Jetpack. If you are using an older version of JetPack, upgrade to JetPack 4.4.

5. For YOLOv3, instructions to build TensorRT OSS on Jetson can be found in the TensorRT OSS on Jetson (ARM64) section above or in this GitHub repo.

6. Run the tlt-converter using the sample command below and generate the engine.

Using the tlt-converter

            

            
tlt-converter [-h] -k <encryption_key>
              -d <input_dimensions>
              -o <comma separated output nodes>
              [-c <path to calibration cache file>]
              [-e <path to output engine>]
              [-b <calibration batch size>]
              [-m <maximum batch size of the TRT engine>]
              [-t <engine datatype>]
              [-w <maximum workspace size of the TRT Engine>]
              [-i <input dimension ordering>]
              [-p <optimization_profiles>]
              [-s]
              [-u <DLA_core>]
              input_file
        

Required Arguments

• input_file: The path to the .etlt model exported using tlt yolo_v3 export.

• -k: The key used to encode the .tlt model when doing the training.

• -d: A comma-separated list of input dimensions that should match the dimensions used for tlt yolo_v3 export.

• -o: A comma-separated list of output blob names that should match the output configuration. used for tlt yolo_v3 export. For YOLOv3, set this argument to BatchedNMS.

• -p: Optimization profiles for .etlt models with dynamic shape. Use a comma-separated list of optimization profile shapes in the format <input_name>,<min_shape>,<opt_shape>,<max_shape>, where each shape has the format: <n>x<c>x<h>x<w>. The input name for YOLOv3 is Input

Optional Arguments

• -e: The path to save the engine to. The default path is ./saved.engine.

• -t: The desired engine data type. The options are fp32, fp16, or int8. Selecting INT8 mode will generate a calibration cache.

• -w: The maximum workspace size for the TensorRT engine. The default value is 1073741824(1<<30).

• -i: The input-dimension ordering. All other TLT commands use NCHW. The options are nchw, nhwc, and nc. The default value is nchw, so you can omit this argument for YOLOv3.

• -s: A Boolean value specifying wheter to apply TensorRT strict-type constraints when building the TensorRT engine.

• -u: Only needed if use DLA core. Specifying DLA core index when building the TensorRT engine on Jetson devices.

INT8 Mode Arguments

• -c: The path to calibration cache file (only used in INT8 mode). The default value is ./cal.bin.

• -b: The batch size used during the export step for INT8 calibration cache generation (default: 8).

• -m: The maximum batch size for the TensorRT engine. The default value is 16. If out-of-memory issues occur, decrease the batch size accordingly. This parameter is not required for .etlt models generated with dynamic shape, which is only possible for new models introduced in TLT 3.0.

Sample Output Log

Here is a sample log for exporting a YOLOv3 model.

            

            
tlt-converter -k $KEY  \
                    -d 3,384,1248 \
                    -o BatchedNMS \
                    -e /export/trt.fp16.engine \
                    -t fp16 \
                    -i nchw \
                    -m 8 \
                    /ws/yolov3_resnet18_epoch_100.etlt
        

Integrating the model to DeepStream

To integrate a model trained by TLT with DeepStream, you shoud generate a device-specific optimized TensorRT engine using tlt-converter. The generated TensorRT engine file can then be ingested by DeepStream (Currently, YOLOv3 etlt files are not supported by DeepStream).

For YOLOv3, you will need to build the TensorRT open source plugins and custom bounding-box parser. The instructions to build TensorRT open source plugins are provided in the TensorRT OSS section above. The instructions to build custom bounding-box parser is provided below in prerequisite section and the required code can be found in this GitHub repo.

To integrate the models with DeepStream, you will need the following:

1. The DeepStream SDK (download from the DeepStream SDK Download Page). The installation instructions for DeepStream are provided in the DeepStream Development Guide.

2. An exported .etlt model file and optional calibration cache for INT8 precision.

3. TensorRT 7+ OSS Plugins .

4. A labels.txt file containing the labels for classes in the order in which the networks produce outputs.

5. A sample config_infer_*.txt file to configure the nvinfer element in DeepStream. The nvinfer element handles everything related to TensorRT optimization and engine creation in DeepStream.

DeepStream SDK ships with an end-to-end reference application which is fully configurable. Users can configure input sources, the inference model, and output sinks. The app requires a primary object-detection model, followed by an optional secondary classification model. The reference application is installed as deepstream-app. The graphic below shows the architecture of the reference application:

Typically, two or more configuration files are used with this app. In the install directory, the config files are located in samples/configs/deepstream-app or sample/configs/tlt_pretrained_models. The main config file configures all the high-level parameters in the pipeline above. This will set the input source and resolution, number of inferences, tracker, and output sinks. The other supporting config files are for each individual inference engine. The inference-specific configuration files are used to specify the models, inference resolution, batch size, number of classes, and other customizations. The main configuration file will call all the supporting configuration files.

Here are some configuration files in samples/configs/deepstream-app for reference:

• source4_1080p_dec_infer-resnet_tracker_sgie_tiled_display_int8.txt: The main configuration file.

• config_infer_primary.txt: The supporting configuration file for the primary detector in the pipeline above.

• config_infer_secondary_*.txt: The supporting configuration file for the secondary classifier in the pipeline above.

The deepstream-app will only work with the main configuration file. This file will most likely remain the same for all models and can be used directly from the DeepStream SDK with little to no change. You will only have to modify or create config_infer_primary.txt and config_infer_secondary_*.txt.

Integrating a YOLOv3 Model

To run a YOLOv3 model in DeepStream, you need a label file and a DeepStream configuration file. In addition, you need to compile the TensorRT 7+ Open source software and YOLOv3 bounding box parser for DeepStream.

A DeepStream sample with documentation on how to run inference using the trained YOLOv3 models from TLT is provided on GitHub repo.

Prerequisite for YOLOv3 Model

1. YOLOv3 requires the batchTilePlugin, resizeNearestPlugin and batchedNMSPlugin. These plugins are available in the TensorRT open source repo, but not in TensorRT 7.0. Detailed instructions to build TensorRT OSS can be found in the TensorRT Open Source Software (OSS) section.

2. YOLOv3 requires custom bounding box parsers that are not built in to the DeepStream SDK. The source code to build custom bounding box parsers for YOLOv3 is available in GitHub repo. The following instructions can be used to build the bounding-box parser:

   1. Install git-lfs (git >= 1.8.2)

      Copy

      Copied!

                  
      
                  
      curl -s https://packagecloud.io/install/repositories/github/git-lfs/
      script.deb.sh | sudo bash
      sudo apt-get install git-lfs
      git lfs install
              

This generates libnvds_infercustomparser_tlt.so in the directory post_processor.

Label File

The label file is a text file containing the names of the classes that the YOLOv3 model is trained to detect. The order in which the classes are listed here must match the order in which the model predicts the output. During the training, TLT YOLOv3 will specify all class names in lower case and sort them in alphabetical order. For example, if the dataset_config is:

            

            
dataset_config {
  data_sources: {
      label_directory_path: "/workspace/tlt-experiments/data/training/label_2"
      image_directory_path: "/workspace/tlt-experiments/data/training/image_2"
  }
  target_class_mapping {
    key: "car"
    value: "car"
  }
  target_class_mapping {
    key: "person"
    value: "person"
  }
  target_class_mapping {
    key: "bicycle"
    value: "bicycle"
  }
  validation_data_sources: {
      label_directory_path: "/workspace/tlt-experiments/data/val/label"
      image_directory_path: "/workspace/tlt-experiments/data/val/image"
  }
}
        

Then the corresponding yolov3_labels.txt file would be:

            

            
bicycle
car
person
        

DeepStream Configuration File

The detection model is typically used as a primary inference engine. It can also be used as a secondary inference engine. To run this model in the sample deepstream-app, you must modify the existing config_infer_primary.txt file to point to this model.

Integrate the TensorRT engine file with the DeepStream app

1. Generate the TensorRT engine using tlt-converter. Detailed instructions are provided in the Generating an engine using tlt-converter section above.

2. Once the engine file is generated successfully, modify the following parameters to use this engine with DeepStream:

            

            
model-engine-file=<PATH to generated TensorRT engine>
        

All other parameters are common between the two approaches. To use the custom bounding box parser instead of the default parsers in DeepStream, modify the following parameters in the [property] section of the primary infer configuration file:

            

            
parse-bbox-func-name=NvDsInferParseCustomBatchedNMSTLT
custom-lib-path=<PATH to libnvds_infercustomparser_tlt.so>
        

Add the label file generated above using the following:

            

            
labelfile-path=<YOLOv3 labels>
        

For all the options, see the configuration file below. To learn more about all the parameters, refer to the DeepStream Development Guide.

Here’s a sample config file, pgie_yolov3_config.txt:

            

            
[property]
gpu-id=0
net-scale-factor=1.0
offsets=103.939;116.779;123.68
model-color-format=1
labelfile-path=<Path to yolov3_labels.txt>
model-engine-file=<PATH to generated TensorRT engine>
tlt-model-key=<Key to decrypt model>
infer-dims=3;384;1248
maintain-aspect-ratio=1
uff-input-order=0
uff-input-blob-name=Input
batch-size=1
## 0=FP32, 1=INT8, 2=FP16 mode
network-mode=0
num-detected-classes=3
interval=0
gie-unique-id=1
is-classifier=0
#network-type=0
#no cluster
cluster-mode=3
output-blob-names=BatchedNMS
parse-bbox-func-name=NvDsInferParseCustomBatchedNMSTLT
custom-lib-path=<Path to libnvds_infercustomparser_tlt.so>

[class-attrs-all]
pre-cluster-threshold=0.3
roi-top-offset=0
roi-bottom-offset=0
detected-min-w=0
detected-min-h=0
detected-max-w=0
detected-max-h=0