DetectNet: Deep Neural Network for Object Detection in DIGITS

The NVIDIA Deep Learning GPU Training System (DIGITS) puts the power of deep learning in the hands of data scientists and researchers. Using DIGITS you can…

Andrew Tao
10 min readintermediate
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Overview

DetectNet is a deep neural network model integrated into NVIDIA's DIGITS platform, designed for efficient object detection in images. The article details its architecture, data format, training process, and inference capabilities, emphasizing its ability to detect multiple objects and generate accurate bounding boxes.

What You'll Learn

1

How to use DetectNet for object detection in images

2

Why a fixed 3-dimensional label format is essential for training DetectNet

3

How to implement online data augmentation in training with DetectNet

Prerequisites & Requirements

  • Understanding of deep learning concepts and neural networks
  • Familiarity with NVIDIA DIGITS and Caffe framework

Key Questions Answered

What is DetectNet and how does it work for object detection?
DetectNet is a deep neural network model designed for object detection in images, using a fixed 3-dimensional label format to predict object classes and bounding box coordinates. It processes images through a fully-convolutional network (FCN) to efficiently detect multiple objects and generate bounding boxes.
How does the training process for DetectNet differ from traditional image classification?
Unlike traditional image classification that uses single-object images, DetectNet requires larger images with multiple objects and bounding box coordinates. It uses a fixed label format to maintain consistency in training data, allowing for effective loss function definition.
What are the key components of DetectNet's architecture?
DetectNet's architecture consists of data layers for image ingestion, a fully-convolutional network for feature extraction, and loss functions to measure prediction errors for object coverage and bounding box corners. This structure allows for efficient training and inference.
What performance metrics are used to evaluate DetectNet's object detection capabilities?
DetectNet uses a simplified mean Average Precision (mAP) score to evaluate performance, calculated from the Intersection over Union (IoU) of predicted and ground truth bounding boxes. This metric assesses the model's sensitivity and precision in detecting objects.

Key Statistics & Figures

Training time
63 minutes
Training DetectNet on a dataset of 307 training images with 24 validation images, all sized 1536×1024 pixels.
Inference time
41 ms
DetectNet can perform inference on 1536×1024 pixel images at approximately 24 FPS using a Titan X GPU.

Technologies & Tools

Software
Digits
Platform for training and deploying deep learning models.
Framework
Caffe
Deep learning framework used for training DetectNet.
Library
Cudnn
GPU-accelerated library for deep neural networks used in conjunction with Caffe.

Key Actionable Insights

1
Utilizing DetectNet's fixed 3-dimensional label format can significantly streamline the training process for object detection tasks.
This approach allows for consistent data representation, making it easier to define loss functions and manage varying numbers of objects in training images.
2
Incorporating online data augmentation during training can enhance the robustness of the DetectNet model.
By applying random transformations to training images, the model becomes less prone to overfitting and can better generalize to variations in object appearance.
3
Leveraging the pre-trained GoogLeNet model as a base for DetectNet can reduce training time and improve accuracy.
This strategy allows DetectNet to benefit from established feature extraction capabilities, enhancing its performance on object detection tasks.

Common Pitfalls

1
Failing to properly configure the grid spacing and stride parameters can lead to suboptimal detection performance.
Incorrect settings may result in missed detections or excessive false positives, as the model may not effectively cover the image area.
2
Neglecting data augmentation can cause the model to overfit to the training dataset.
Without augmentation, the model may struggle to generalize to new images, leading to poor performance in real-world applications.

Related Concepts

Deep Learning For Object Detection
Fully-convolutional Networks
Bounding Box Regression
Mean Average Precision (map)