Hi!
I have just pushed the test folder to the repo: https://github.com/node21challenge/node21_generation_baseline/tree/main/test , which contains a test image (3D image where several CXR images are stacked together), and the corresponding nodules.json file. You could use that to test if your algorithm works as expected.
Indeed, for the zenodo release we do not provide nodules.json format. We expected that you could directly work with csv format (which is a more standard format) for your experiments before creating an algorithm container for submission. Nodules.json format (and 3D image) is only used for algorithm submission to grand-challenge. But if you would like to work directly with this format (3D image and nodules.json format) as explained in the template repo, you could transform simulated location csv to nodules.json format similarly as it was done in this function. Bear in mind that you would need to stack CXR images into a single 3D image, and the z coordinate in the nodules.json file will be used as the identifier of the image as explained here.
If something is unclear and you need help, please let us know :)
Good luck!
Ecem