Hey, guys! I’ve just partly fixed the problem(fix the problem using COCO dataset). Now, I can use lr_find(learn) and learn.recorder.plot() without error. Also see this link:Image Segmentation on COCO dataset - summary, questions and suggestions.
I think there are 2 problems in this error: 1)The value of the mask array should be {0,1}, not {0,255}or some other stuff, that’s what many other people said. The link above find ways to generate {0,1} mask. But how to fix it by not transforming data into COCO form, I haven’t tried; 2)The class list. Mine is a bynary segmentation project(to segment “row” ), so CATEGORY_NAMES=[0, ‘row’]. If CATEGORY_NAMES=[‘row’], I found the loss would always be 0, when using lr_find(learn) and learn.recorder.plot().
I think there still are something more to figure out, but for now, at leat I can use unet and lr_find(learn).