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Pre-trained Segformer - CityScapes

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Pre-trained segformer models trained on CityScapes.



Latest Version



September 27, 2023


39.54 MB

Cityscapes SegFormer Model Card

Model Overview

The model described in this card segments cityscapes urban city classes within an image and returns a semantic segmentation mask.

Model Architecture

Segformer is a real-time state of the art transformer based semantic segmentation model. SegFormer is a simple, efficient yet powerful semantic segmentation framework which unifies Transformers with lightweight multilayer perception (MLP) decoders. It then predicts a class label for every pixel in the input image. This model was trained on the cityscapes dataset and segments the urban cityscapes 19 classes which include:

  1. road
  2. sidewalk
  3. building
  4. wall
  5. fence
  6. pole
  7. traffic light
  8. traffic sign
  9. vegetation
  10. terrain
  11. sky
  12. person
  13. rider
  14. car
  15. truck
  16. bus
  17. train
  18. motorcycle
  19. bicycle

Training Algorithm

The training algorithm optimizes the network to minimize the cross-entropy loss for every pixel of the mask.

Training Data Ground-truth Labeling Guidelines

  • This model was trained on the cityscapes dataset[3].


Evaluation Data

The inference performance of Cityscapes model was measured on the cityscapes validation dataset.

Methodology and KPI

The KPI for the evaluation data are reported in the table below. Model is evaluated based on Mean Intersection-Over-Union. Mean Intersection-Over-Union (MIOU) is a common evaluation metric for semantic image segmentation, which first computes the IOU for each semantic class and then computes the average over classes.

Model Cityscapes SegFormer
fan_hybrid_base 83.5

Real-time Inference Performance

The inference is run on the provided unpruned models at INT8 precision. On the Jetson Nano FP16 precision is used. The inference performance is run using trtexec on Jetson Nano, AGX Xavier, Xavier NX and NVIDIA T4 GPU. The Jetson devices are running at Max-N configuration for maximum GPU frequency. The performance shown here is the inference only performance. The end-to-end performance with streaming video data might slightly vary depending on other bottlenecks in the hardware and software.

BS - Batch Size


Platform BS FPS
Jetson Orin Nano - -
Orin NX 16GB - -
AGX Orin 64GB - -
A2 16 230
T4 16 374
A30 16 1098
L4 4 750
L40 8 1985
A100 64 2381
H100 64 4189


Platform BS FPS
Jetson Orin Nano - -
Orin NX 16GB - -
AGX Orin 64GB - -
A2 16 174
T4 8 272
A30 16 834
L4 4 581
L40 8 1510
A100 64 1808
H100 64 3143


Platform BS FPS
Jetson Orin Nano - -
Orin NX 16GB - -
AGX Orin 64GB - -
A2 16 129
T4 8 198
A30 16 606
L4 4 442
L40 8 1144
A100 64 1808
H100 64 2306


Platform BS FPS
Jetson Orin Nano - -
Orin NX 16GB - -
AGX Orin 64GB - -
A2 16 97.7
T4 8 156.7
A30 16 465
L4 4 341
L40 8 840
A100 64 1000
H100 64 1732

How to use this model

These models need to be used with NVIDIA Hardware and Software. For Hardware, the models can run on any NVIDIA GPU including NVIDIA Jetson devices. These models can only be used with Train Adapt Optimize (TAO) Toolkit, DeepStream SDK or TensorRT.

The model is intended for primarily deploying and doing inference using DeepStream.

Primary use case intended for the model is segmenting urban city classes in a color (RGB) image. The model can be used to segment urban city transport/ setting from photos and videos by using appropriate video or image decoding and pre-processing. Note this model performs semantic segmentation and not instance based segmentation.


Color Images of resolution 1024x1024x3 which the model was trained with. Any resolution input can be fed into the model.


Outputs a semantic of urban city classes for the input image.

Output image

Instructions to deploy these models with DeepStream

To create the entire end-to-end video analytics application, deploy these models with DeepStream SDK. DeepStream SDK is a streaming analytics toolkit to accelerate building AI-based video analytics applications. DeepStream supports direct integration of these models into the deepstream sample app.

To deploy these models with DeepStream 6.1, please follow the instructions below:

Download and install DeepStream SDK. The installation instructions for DeepStream are provided in DeepStream development guide. The config files for the purpose-built models are located in:

/opt/nvidia/deepstream is the default DeepStream installation directory. This path will be different if you are installing in a different directory.

You will need 1 config files and 1 label file. These files are provided in [NVIDIA-AI-IOT](@todo : update).

nvinfer_config.txt - File to configure inference settings for Cityscapes
labels.txt - Label file with 19 classes

Key Parameters in nvinfer_config.txt

# You can either provide the onnx model and key or trt engine obtained by using tao-converter
# onnx-file=../../path/to/.onnx file
# Since the model input channel is 3, using RGB color format.
## 0=FP32, 1=INT8, 2=FP16 mode
## 0=Detector, 1=Classifier, 2=Semantic Segmentation, 3=Instance Segmentation, 100=Other

Run ds-tao-segmentation:

ds-tao-segmentation -c nvinfer_config.txt -i file:///opt/nvidia/deepstream/deepstream/samples/streams/sample_720p.mp4

Documentation to deploy with DeepStream is provided in "Deploying to DeepStream" chapter of TAO User Guide.


Under-represented classes

NVIDIA Cityscapes model was trained to detect classes that are predominantly found in road transport setting. It relatively performs poorly on under-represented classes in our internal Intelligent Transport System dataset. Some of these classes include: rider, truck, train, motorcycle.

Model versions:

FAN Cityscapes:
  • trainable_fan_base_hybrid_v1.0 - cityscapes FAN Base Hybrid model trainable.
  • trainable_fan_tiny_hybrid_v1.0 - cityscapes FAN Tiny Hybrid model trainable.
  • trainable_fan_small_hybrid_v1.0 - cityscapes FAN Small Hybrid model trainable.
  • deployable_fan_base_hybrid_v1.0 - cityscapes FAN Base Hybrid model deployable to deepstream.
  • deployable_fan_tiny_hybrid_v1.0 - cityscapes FAN Tiny Hybrid model deployable to deepstream.
  • deployable_fan_small_hybrid_v1.0 - cityscapes FAN Small Hybrid model deployable to deepstream.



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This work is licensed under the Creative Commons Attribution NonCommercial ShareAlike 4.0 License (CC-BY-NC-SA-4.0). To view a copy of this license, please visit this link, or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Ethical Considerations

Training and evaluation dataset mostly consists of North American content. An ideal training and evaluation dataset would additionally include content from other geographies.

NVIDIA’s platforms and application frameworks enable developers to build a wide array of AI applications. Consider potential algorithmic bias when choosing or creating the models being deployed. Work with the model’s developer to ensure that it meets the requirements for the relevant industry and use case; that the necessary instruction and documentation are provided to understand error rates, confidence intervals, and results; and that the model is being used under the conditions and in the manner intended.