%reload_ext autoreload
%autoreload 2
%matplotlib inline

from fastai import *
from fastai.vision import *
from fastai.callbacks.hooks import *

path = Path('./data/camvid-tiramisu')

path.ls()

fnames = get_image_files(path/'val')
fnames[:3]

lbl_names = get_image_files(path/'valannot')
lbl_names[:3]

img_f = fnames[0]
img = open_image(img_f)
img.show(figsize=(5,5))

def get_y_fn(x): return Path(str(x.parent)+'annot')/x.name

codes = array(['Sky', 'Building', 'Pole', 'Road', 'Sidewalk', 'Tree',
    'Sign', 'Fence', 'Car', 'Pedestrian', 'Cyclist', 'Void'])

mask = open_mask(get_y_fn(img_f))
mask.show(figsize=(5,5), alpha=1)

src_size = np.array(mask.shape[1:])
src_size,mask.data

bs,size = 8,src_size//2

src = (SegmentationItemList.from_folder(path)
       .split_by_folder(valid='val')
       .label_from_func(get_y_fn, classes=codes))

data = (src.transform(get_transforms(), tfm_y=True)
        .databunch(bs=bs)
        .normalize(imagenet_stats))

data.show_batch(2, figsize=(10,7))

name2id = {v:k for k,v in enumerate(codes)}
void_code = name2id['Void']

def acc_camvid(input, target):
    target = target.squeeze(1)
    mask = target != void_code
    return (input.argmax(dim=1)[mask]==target[mask]).float().mean()

metrics=acc_camvid
wd=1e-2

learn = unet_learner(data, models.resnet34, metrics=metrics, wd=wd, bottle=True)

lr_find(learn)
learn.recorder.plot()

lr=2e-3

learn.fit_one_cycle(10, slice(lr), pct_start=0.8)

learn.save('stage-1')

learn.load('stage-1');

learn.unfreeze()

lrs = slice(lr/100,lr)

learn.fit_one_cycle(12, lrs, pct_start=0.8)

learn.save('stage-2');

learn=None
gc.collect()

size = src_size
bs=8

data = (src.transform(get_transforms(), size=size, tfm_y=True)
        .databunch(bs=bs)
        .normalize(imagenet_stats))

learn = unet_learner(data, models.resnet34, metrics=metrics, wd=wd, bottle=True).load('stage-2');

lr_find(learn)
learn.recorder.plot()

lr=1e-3

learn.fit_one_cycle(10, slice(lr), pct_start=0.8)

learn.save('stage-1-big')

learn.load('stage-1-big');

learn.unfreeze()

lrs = slice(lr/1000,lr/10)

learn.fit_one_cycle(10, lrs)

learn.save('stage-2-big')

learn.load('stage-2-big');

learn.show_results(rows=3, figsize=(9,11))

# start: 480x360

print(learn.summary())