Convert Cityscapes to COCO format: How to convert to other classes (ex: traffic light)

[MarceloContreras]

Has somebody successfully converted cityscapes dataset filtering classes such as traffic lights, poles, etc? Indeed, I did the change of desired classes in category_instancesonly and also commented on the invalid contour warning. However, even if I did that, I still get .json output files with 0 annotations after loading all the images.

[Aryan-Mishra24]

To successfully convert the Cityscapes dataset while filtering specific classes such as traffic lights and poles, you can follow the steps below:

First, clone the Cityscapes scripts repository:
bash

git clone https://github.com/mcordts/cityscapesScripts.git
cd cityscapesScripts/cityscapesscripts/preparation
Modify the createTrainIdInstanceImgs.py script to filter out specific classes. In the createTrainIdInstanceImgs.py file, find the following lines:
python

Load the annotation

objects = csHelpers.loadAnnotaton(labelImgPath)
Add a filtering function after the lines mentioned above:
python

def filter_objects(objects, classes_to_keep):
filtered_objects = []
for obj in objects:
if obj.label.name in classes_to_keep:
filtered_objects.append(obj)
return filtered_objects

classes_to_keep = ['traffic light', 'pole']
objects = filter_objects(objects, classes_to_keep)
Replace the classes_to_keep list with the classes you want to keep in the final annotations.

In the json2instanceImg.py script, find the following line:
python

if not anno['regions']:
Replace the above line with the following:
python

if len(anno['regions']) == 0:
Now you can run the createTrainIdInstanceImgs.py script to generate the filtered dataset:
bash

python createTrainIdInstanceImgs.py --cityscapesPath path/to/cityscapes --outputPath path/to/output
Finally, run the json2instanceImg.py script to convert the modified annotations to JSON files:
bash
python json2instanceImg.py --cityscapesPath path/to/cityscapes --outputPath path/to/output
After following these steps, the output JSON files should contain only the filtered classes (e.g., traffic lights and poles). Make sure to replace path/to/cityscapes with the path to your Cityscapes dataset and path/to/output with your desired output path.