LN3Diff_I23D / vit /utils.py
NIRVANALAN
init
11e6f7b
# https://raw.githubusercontent.com/facebookresearch/dino/main/utils.py
# Copyright (c) Facebook, Inc. and its affiliates.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Misc functions.
Mostly copy-paste from torchvision references or other public repos like DETR:
https://github.com/facebookresearch/detr/blob/master/util/misc.py
"""
import os
import sys
import time
import math
import random
import datetime
import subprocess
from collections import defaultdict, deque
import numpy as np
import torch
from torch import nn
import torch.distributed as dist
from PIL import ImageFilter, ImageOps
class GaussianBlur(object):
"""
Apply Gaussian Blur to the PIL image.
"""
def __init__(self, p=0.5, radius_min=0.1, radius_max=2.):
self.prob = p
self.radius_min = radius_min
self.radius_max = radius_max
def __call__(self, img):
do_it = random.random() <= self.prob
if not do_it:
return img
return img.filter(
ImageFilter.GaussianBlur(
radius=random.uniform(self.radius_min, self.radius_max)))
class Solarization(object):
"""
Apply Solarization to the PIL image.
"""
def __init__(self, p):
self.p = p
def __call__(self, img):
if random.random() < self.p:
return ImageOps.solarize(img)
else:
return img
def load_pretrained_weights(model, pretrained_weights, checkpoint_key,
model_name, patch_size):
if os.path.isfile(pretrained_weights):
state_dict = torch.load(pretrained_weights, map_location="cpu")
if checkpoint_key is not None and checkpoint_key in state_dict:
print(f"Take key {checkpoint_key} in provided checkpoint dict")
state_dict = state_dict[checkpoint_key]
# remove `module.` prefix
state_dict = {
k.replace("module.", ""): v
for k, v in state_dict.items()
}
# remove `backbone.` prefix induced by multicrop wrapper
state_dict = {
k.replace("backbone.", ""): v
for k, v in state_dict.items()
}
msg = model.load_state_dict(state_dict, strict=False)
print('Pretrained weights found at {} and loaded with msg: {}'.format(
pretrained_weights, msg))
else:
print(
"Please use the `--pretrained_weights` argument to indicate the path of the checkpoint to evaluate."
)
url = None
if model_name == "vit_small" and patch_size == 16:
url = "dino_deitsmall16_pretrain/dino_deitsmall16_pretrain.pth"
elif model_name == "vit_small" and patch_size == 8:
url = "dino_deitsmall8_pretrain/dino_deitsmall8_pretrain.pth"
elif model_name == "vit_base" and patch_size == 16:
url = "dino_vitbase16_pretrain/dino_vitbase16_pretrain.pth"
elif model_name == "vit_base" and patch_size == 8:
url = "dino_vitbase8_pretrain/dino_vitbase8_pretrain.pth"
elif model_name == "xcit_small_12_p16":
url = "dino_xcit_small_12_p16_pretrain/dino_xcit_small_12_p16_pretrain.pth"
elif model_name == "xcit_small_12_p8":
url = "dino_xcit_small_12_p8_pretrain/dino_xcit_small_12_p8_pretrain.pth"
elif model_name == "xcit_medium_24_p16":
url = "dino_xcit_medium_24_p16_pretrain/dino_xcit_medium_24_p16_pretrain.pth"
elif model_name == "xcit_medium_24_p8":
url = "dino_xcit_medium_24_p8_pretrain/dino_xcit_medium_24_p8_pretrain.pth"
elif model_name == "resnet50":
url = "dino_resnet50_pretrain/dino_resnet50_pretrain.pth"
if url is not None:
print(
"Since no pretrained weights have been provided, we load the reference pretrained DINO weights."
)
state_dict = torch.hub.load_state_dict_from_url(
url="https://dl.fbaipublicfiles.com/dino/" + url)
model.load_state_dict(state_dict, strict=True)
else:
print(
"There is no reference weights available for this model => We use random weights."
)
def load_pretrained_linear_weights(linear_classifier, model_name, patch_size):
url = None
if model_name == "vit_small" and patch_size == 16:
url = "dino_deitsmall16_pretrain/dino_deitsmall16_linearweights.pth"
elif model_name == "vit_small" and patch_size == 8:
url = "dino_deitsmall8_pretrain/dino_deitsmall8_linearweights.pth"
elif model_name == "vit_base" and patch_size == 16:
url = "dino_vitbase16_pretrain/dino_vitbase16_linearweights.pth"
elif model_name == "vit_base" and patch_size == 8:
url = "dino_vitbase8_pretrain/dino_vitbase8_linearweights.pth"
elif model_name == "resnet50":
url = "dino_resnet50_pretrain/dino_resnet50_linearweights.pth"
if url is not None:
print("We load the reference pretrained linear weights.")
state_dict = torch.hub.load_state_dict_from_url(
url="https://dl.fbaipublicfiles.com/dino/" + url)["state_dict"]
linear_classifier.load_state_dict(state_dict, strict=True)
else:
print("We use random linear weights.")
def clip_gradients(model, clip):
norms = []
for name, p in model.named_parameters():
if p.grad is not None:
param_norm = p.grad.data.norm(2)
norms.append(param_norm.item())
clip_coef = clip / (param_norm + 1e-6)
if clip_coef < 1:
p.grad.data.mul_(clip_coef)
return norms
def cancel_gradients_last_layer(epoch, model, freeze_last_layer):
if epoch >= freeze_last_layer:
return
for n, p in model.named_parameters():
if "last_layer" in n:
p.grad = None
def restart_from_checkpoint(ckp_path, run_variables=None, **kwargs):
"""
Re-start from checkpoint
"""
if not os.path.isfile(ckp_path):
return
print("Found checkpoint at {}".format(ckp_path))
# open checkpoint file
checkpoint = torch.load(ckp_path, map_location="cpu")
# key is what to look for in the checkpoint file
# value is the object to load
# example: {'state_dict': model}
for key, value in kwargs.items():
if key in checkpoint and value is not None:
try:
msg = value.load_state_dict(checkpoint[key], strict=False)
print("=> loaded '{}' from checkpoint '{}' with msg {}".format(
key, ckp_path, msg))
except TypeError:
try:
msg = value.load_state_dict(checkpoint[key])
print("=> loaded '{}' from checkpoint: '{}'".format(
key, ckp_path))
except ValueError:
print(
"=> failed to load '{}' from checkpoint: '{}'".format(
key, ckp_path))
else:
print("=> key '{}' not found in checkpoint: '{}'".format(
key, ckp_path))
# re load variable important for the run
if run_variables is not None:
for var_name in run_variables:
if var_name in checkpoint:
run_variables[var_name] = checkpoint[var_name]
def cosine_scheduler(base_value,
final_value,
epochs,
niter_per_ep,
warmup_epochs=0,
start_warmup_value=0):
warmup_schedule = np.array([])
warmup_iters = warmup_epochs * niter_per_ep
if warmup_epochs > 0:
warmup_schedule = np.linspace(start_warmup_value, base_value,
warmup_iters)
iters = np.arange(epochs * niter_per_ep - warmup_iters)
schedule = final_value + 0.5 * (base_value - final_value) * (
1 + np.cos(np.pi * iters / len(iters)))
schedule = np.concatenate((warmup_schedule, schedule))
assert len(schedule) == epochs * niter_per_ep
return schedule
def bool_flag(s):
"""
Parse boolean arguments from the command line.
"""
FALSY_STRINGS = {"off", "false", "0"}
TRUTHY_STRINGS = {"on", "true", "1"}
if s.lower() in FALSY_STRINGS:
return False
elif s.lower() in TRUTHY_STRINGS:
return True
else:
raise argparse.ArgumentTypeError("invalid value for a boolean flag")
def fix_random_seeds(seed=31):
"""
Fix random seeds.
"""
torch.manual_seed(seed)
torch.cuda.manual_seed_all(seed)
np.random.seed(seed)
class SmoothedValue(object):
"""Track a series of values and provide access to smoothed values over a
window or the global series average.
"""
def __init__(self, window_size=20, fmt=None):
if fmt is None:
fmt = "{median:.6f} ({global_avg:.6f})"
self.deque = deque(maxlen=window_size)
self.total = 0.0
self.count = 0
self.fmt = fmt
def update(self, value, n=1):
self.deque.append(value)
self.count += n
self.total += value * n
def synchronize_between_processes(self):
"""
Warning: does not synchronize the deque!
"""
if not is_dist_avail_and_initialized():
return
t = torch.tensor([self.count, self.total],
dtype=torch.float64,
device='cuda')
dist.barrier()
dist.all_reduce(t)
t = t.tolist()
self.count = int(t[0])
self.total = t[1]
@property
def median(self):
d = torch.tensor(list(self.deque))
return d.median().item()
@property
def avg(self):
d = torch.tensor(list(self.deque), dtype=torch.float32)
return d.mean().item()
@property
def global_avg(self):
return self.total / self.count
@property
def max(self):
return max(self.deque)
@property
def value(self):
return self.deque[-1]
def __str__(self):
return self.fmt.format(median=self.median,
avg=self.avg,
global_avg=self.global_avg,
max=self.max,
value=self.value)
def reduce_dict(input_dict, average=True):
"""
Args:
input_dict (dict): all the values will be reduced
average (bool): whether to do average or sum
Reduce the values in the dictionary from all processes so that all processes
have the averaged results. Returns a dict with the same fields as
input_dict, after reduction.
"""
world_size = get_world_size()
if world_size < 2:
return input_dict
with torch.no_grad():
names = []
values = []
# sort the keys so that they are consistent across processes
for k in sorted(input_dict.keys()):
names.append(k)
values.append(input_dict[k])
values = torch.stack(values, dim=0)
dist.all_reduce(values)
if average:
values /= world_size
reduced_dict = {k: v for k, v in zip(names, values)}
return reduced_dict
class MetricLogger(object):
def __init__(self, delimiter="\t"):
self.meters = defaultdict(SmoothedValue)
self.delimiter = delimiter
def update(self, **kwargs):
for k, v in kwargs.items():
if isinstance(v, torch.Tensor):
v = v.item()
assert isinstance(v, (float, int))
self.meters[k].update(v)
def __getattr__(self, attr):
if attr in self.meters:
return self.meters[attr]
if attr in self.__dict__:
return self.__dict__[attr]
raise AttributeError("'{}' object has no attribute '{}'".format(
type(self).__name__, attr))
def __str__(self):
loss_str = []
for name, meter in self.meters.items():
loss_str.append("{}: {}".format(name, str(meter)))
return self.delimiter.join(loss_str)
def synchronize_between_processes(self):
for meter in self.meters.values():
meter.synchronize_between_processes()
def add_meter(self, name, meter):
self.meters[name] = meter
def log_every(self, iterable, print_freq, header=None):
i = 0
if not header:
header = ''
start_time = time.time()
end = time.time()
iter_time = SmoothedValue(fmt='{avg:.6f}')
data_time = SmoothedValue(fmt='{avg:.6f}')
space_fmt = ':' + str(len(str(len(iterable)))) + 'd'
if torch.cuda.is_available():
log_msg = self.delimiter.join([
header, '[{0' + space_fmt + '}/{1}]', 'eta: {eta}', '{meters}',
'time: {time}', 'data: {data}', 'max mem: {memory:.0f}'
])
else:
log_msg = self.delimiter.join([
header, '[{0' + space_fmt + '}/{1}]', 'eta: {eta}', '{meters}',
'time: {time}', 'data: {data}'
])
MB = 1024.0 * 1024.0
for obj in iterable:
data_time.update(time.time() - end)
yield obj
iter_time.update(time.time() - end)
if i % print_freq == 0 or i == len(iterable) - 1:
eta_seconds = iter_time.global_avg * (len(iterable) - i)
eta_string = str(datetime.timedelta(seconds=int(eta_seconds)))
if torch.cuda.is_available():
print(
log_msg.format(
i,
len(iterable),
eta=eta_string,
meters=str(self),
time=str(iter_time),
data=str(data_time),
memory=torch.cuda.max_memory_allocated() / MB))
else:
print(
log_msg.format(i,
len(iterable),
eta=eta_string,
meters=str(self),
time=str(iter_time),
data=str(data_time)))
i += 1
end = time.time()
total_time = time.time() - start_time
total_time_str = str(datetime.timedelta(seconds=int(total_time)))
print('{} Total time: {} ({:.6f} s / it)'.format(
header, total_time_str, total_time / len(iterable)))
def get_sha():
cwd = os.path.dirname(os.path.abspath(__file__))
def _run(command):
return subprocess.check_output(command,
cwd=cwd).decode('ascii').strip()
sha = 'N/A'
diff = "clean"
branch = 'N/A'
try:
sha = _run(['git', 'rev-parse', 'HEAD'])
subprocess.check_output(['git', 'diff'], cwd=cwd)
diff = _run(['git', 'diff-index', 'HEAD'])
diff = "has uncommited changes" if diff else "clean"
branch = _run(['git', 'rev-parse', '--abbrev-ref', 'HEAD'])
except Exception:
pass
message = f"sha: {sha}, status: {diff}, branch: {branch}"
return message
def is_dist_avail_and_initialized():
if not dist.is_available():
return False
if not dist.is_initialized():
return False
return True
def get_world_size():
if not is_dist_avail_and_initialized():
return 1
return dist.get_world_size()
def get_rank():
if not is_dist_avail_and_initialized():
return 0
return dist.get_rank()
def is_main_process():
return get_rank() == 0
def save_on_master(*args, **kwargs):
if is_main_process():
torch.save(*args, **kwargs)
def setup_for_distributed(is_master):
"""
This function disables printing when not in master process
"""
import builtins as __builtin__
builtin_print = __builtin__.print
def print(*args, **kwargs):
force = kwargs.pop('force', False)
if is_master or force:
builtin_print(*args, **kwargs)
__builtin__.print = print
def init_distributed_mode(args):
# launched with torch.distributed.launch
if 'RANK' in os.environ and 'WORLD_SIZE' in os.environ:
args.rank = int(os.environ["RANK"])
args.world_size = int(os.environ['WORLD_SIZE'])
args.gpu = int(os.environ['LOCAL_RANK'])
# launched with submitit on a slurm cluster
elif 'SLURM_PROCID' in os.environ:
args.rank = int(os.environ['SLURM_PROCID'])
args.gpu = args.rank % torch.cuda.device_count()
# launched naively with `python main_dino.py`
# we manually add MASTER_ADDR and MASTER_PORT to env variables
elif torch.cuda.is_available():
print('Will run the code on one GPU.')
args.rank, args.gpu, args.world_size = 0, 0, 1
os.environ['MASTER_ADDR'] = '127.0.0.1'
os.environ['MASTER_PORT'] = '29500'
else:
print('Does not support training without GPU.')
sys.exit(1)
dist.init_process_group(
backend="nccl",
init_method=args.dist_url,
world_size=args.world_size,
rank=args.rank,
)
torch.cuda.set_device(args.gpu)
print('| distributed init (rank {}): {}'.format(args.rank, args.dist_url),
flush=True)
dist.barrier()
setup_for_distributed(args.rank == 0)
def accuracy(output, target, topk=(1, )):
"""Computes the accuracy over the k top predictions for the specified values of k"""
maxk = max(topk)
batch_size = target.size(0)
_, pred = output.topk(maxk, 1, True, True)
pred = pred.t()
correct = pred.eq(target.reshape(1, -1).expand_as(pred))
return [
correct[:k].reshape(-1).float().sum(0) * 100. / batch_size
for k in topk
]
def _no_grad_trunc_normal_(tensor, mean, std, a, b):
# Cut & paste from PyTorch official master until it's in a few official releases - RW
# Method based on https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf
def norm_cdf(x):
# Computes standard normal cumulative distribution function
return (1. + math.erf(x / math.sqrt(2.))) / 2.
if (mean < a - 2 * std) or (mean > b + 2 * std):
warnings.warn(
"mean is more than 2 std from [a, b] in nn.init.trunc_normal_. "
"The distribution of values may be incorrect.",
stacklevel=2)
with torch.no_grad():
# Values are generated by using a truncated uniform distribution and
# then using the inverse CDF for the normal distribution.
# Get upper and lower cdf values
l = norm_cdf((a - mean) / std)
u = norm_cdf((b - mean) / std)
# Uniformly fill tensor with values from [l, u], then translate to
# [2l-1, 2u-1].
tensor.uniform_(2 * l - 1, 2 * u - 1)
# Use inverse cdf transform for normal distribution to get truncated
# standard normal
tensor.erfinv_()
# Transform to proper mean, std
tensor.mul_(std * math.sqrt(2.))
tensor.add_(mean)
# Clamp to ensure it's in the proper range
tensor.clamp_(min=a, max=b)
return tensor
def trunc_normal_(tensor, mean=0., std=1., a=-2., b=2.):
# type: (Tensor, float, float, float, float) -> Tensor
return _no_grad_trunc_normal_(tensor, mean, std, a, b)
class LARS(torch.optim.Optimizer):
"""
Almost copy-paste from https://github.com/facebookresearch/barlowtwins/blob/main/main.py
"""
def __init__(self,
params,
lr=0,
weight_decay=0,
momentum=0.9,
eta=0.001,
weight_decay_filter=None,
lars_adaptation_filter=None):
defaults = dict(lr=lr,
weight_decay=weight_decay,
momentum=momentum,
eta=eta,
weight_decay_filter=weight_decay_filter,
lars_adaptation_filter=lars_adaptation_filter)
super().__init__(params, defaults)
@torch.no_grad()
def step(self):
for g in self.param_groups:
for p in g['params']:
dp = p.grad
if dp is None:
continue
if p.ndim != 1:
dp = dp.add(p, alpha=g['weight_decay'])
if p.ndim != 1:
param_norm = torch.norm(p)
update_norm = torch.norm(dp)
one = torch.ones_like(param_norm)
q = torch.where(
param_norm > 0.,
torch.where(update_norm > 0,
(g['eta'] * param_norm / update_norm),
one), one)
dp = dp.mul(q)
param_state = self.state[p]
if 'mu' not in param_state:
param_state['mu'] = torch.zeros_like(p)
mu = param_state['mu']
mu.mul_(g['momentum']).add_(dp)
p.add_(mu, alpha=-g['lr'])
class MultiCropWrapper(nn.Module):
"""
Perform forward pass separately on each resolution input.
The inputs corresponding to a single resolution are clubbed and single
forward is run on the same resolution inputs. Hence we do several
forward passes = number of different resolutions used. We then
concatenate all the output features and run the head forward on these
concatenated features.
"""
def __init__(self, backbone, head):
super(MultiCropWrapper, self).__init__()
# disable layers dedicated to ImageNet labels classification
backbone.fc, backbone.head = nn.Identity(), nn.Identity()
self.backbone = backbone
self.head = head
def forward(self, x):
# convert to list
if not isinstance(x, list):
x = [x]
idx_crops = torch.cumsum(
torch.unique_consecutive(
torch.tensor([inp.shape[-1] for inp in x]),
return_counts=True,
)[1], 0)
start_idx, output = 0, torch.empty(0).to(x[0].device)
for end_idx in idx_crops:
_out = self.backbone(torch.cat(x[start_idx:end_idx]))
# The output is a tuple with XCiT model. See:
# https://github.com/facebookresearch/xcit/blob/master/xcit.py#L404-L405
if isinstance(_out, tuple):
_out = _out[0]
# accumulate outputs
output = torch.cat((output, _out))
start_idx = end_idx
# Run the head forward on the concatenated features.
return self.head(output)
def get_params_groups(model):
regularized = []
not_regularized = []
for name, param in model.named_parameters():
if not param.requires_grad:
continue
# we do not regularize biases nor Norm parameters
if name.endswith(".bias") or len(param.shape) == 1:
not_regularized.append(param)
else:
regularized.append(param)
return [{
'params': regularized
}, {
'params': not_regularized,
'weight_decay': 0.
}]
def has_batchnorms(model):
bn_types = (nn.BatchNorm1d, nn.BatchNorm2d, nn.BatchNorm3d,
nn.SyncBatchNorm)
for name, module in model.named_modules():
if isinstance(module, bn_types):
return True
return False
class PCA():
"""
Class to compute and apply PCA.
"""
def __init__(self, dim=256, whit=0.5):
self.dim = dim
self.whit = whit
self.mean = None
def train_pca(self, cov):
"""
Takes a covariance matrix (np.ndarray) as input.
"""
d, v = np.linalg.eigh(cov)
eps = d.max() * 1e-5
n_0 = (d < eps).sum()
if n_0 > 0:
d[d < eps] = eps
# total energy
totenergy = d.sum()
# sort eigenvectors with eigenvalues order
idx = np.argsort(d)[::-1][:self.dim]
d = d[idx]
v = v[:, idx]
print("keeping %.2f %% of the energy" % (d.sum() / totenergy * 100.0))
# for the whitening
d = np.diag(1. / d**self.whit)
# principal components
self.dvt = np.dot(d, v.T)
def apply(self, x):
# input is from numpy
if isinstance(x, np.ndarray):
if self.mean is not None:
x -= self.mean
return np.dot(self.dvt, x.T).T
# input is from torch and is on GPU
if x.is_cuda:
if self.mean is not None:
x -= torch.cuda.FloatTensor(self.mean)
return torch.mm(torch.cuda.FloatTensor(self.dvt),
x.transpose(0, 1)).transpose(0, 1)
# input if from torch, on CPU
if self.mean is not None:
x -= torch.FloatTensor(self.mean)
return torch.mm(torch.FloatTensor(self.dvt),
x.transpose(0, 1)).transpose(0, 1)
def compute_ap(ranks, nres):
"""
Computes average precision for given ranked indexes.
Arguments
---------
ranks : zerro-based ranks of positive images
nres : number of positive images
Returns
-------
ap : average precision
"""
# number of images ranked by the system
nimgranks = len(ranks)
# accumulate trapezoids in PR-plot
ap = 0
recall_step = 1. / nres
for j in np.arange(nimgranks):
rank = ranks[j]
if rank == 0:
precision_0 = 1.
else:
precision_0 = float(j) / rank
precision_1 = float(j + 1) / (rank + 1)
ap += (precision_0 + precision_1) * recall_step / 2.
return ap
def compute_map(ranks, gnd, kappas=[]):
"""
Computes the mAP for a given set of returned results.
Usage:
map = compute_map (ranks, gnd)
computes mean average precsion (map) only
map, aps, pr, prs = compute_map (ranks, gnd, kappas)
computes mean average precision (map), average precision (aps) for each query
computes mean precision at kappas (pr), precision at kappas (prs) for each query
Notes:
1) ranks starts from 0, ranks.shape = db_size X #queries
2) The junk results (e.g., the query itself) should be declared in the gnd stuct array
3) If there are no positive images for some query, that query is excluded from the evaluation
"""
map = 0.
nq = len(gnd) # number of queries
aps = np.zeros(nq)
pr = np.zeros(len(kappas))
prs = np.zeros((nq, len(kappas)))
nempty = 0
for i in np.arange(nq):
qgnd = np.array(gnd[i]['ok'])
# no positive images, skip from the average
if qgnd.shape[0] == 0:
aps[i] = float('nan')
prs[i, :] = float('nan')
nempty += 1
continue
try:
qgndj = np.array(gnd[i]['junk'])
except:
qgndj = np.empty(0)
# sorted positions of positive and junk images (0 based)
pos = np.arange(ranks.shape[0])[np.in1d(ranks[:, i], qgnd)]
junk = np.arange(ranks.shape[0])[np.in1d(ranks[:, i], qgndj)]
k = 0
ij = 0
if len(junk):
# decrease positions of positives based on the number of
# junk images appearing before them
ip = 0
while (ip < len(pos)):
while (ij < len(junk) and pos[ip] > junk[ij]):
k += 1
ij += 1
pos[ip] = pos[ip] - k
ip += 1
# compute ap
ap = compute_ap(pos, len(qgnd))
map = map + ap
aps[i] = ap
# compute precision @ k
pos += 1 # get it to 1-based
for j in np.arange(len(kappas)):
kq = min(max(pos), kappas[j])
prs[i, j] = (pos <= kq).sum() / kq
pr = pr + prs[i, :]
map = map / (nq - nempty)
pr = pr / (nq - nempty)
return map, aps, pr, prs
def multi_scale(samples, model):
v = None
for s in [1, 1 / 2**(1 / 2), 1 / 2]: # we use 3 different scales
if s == 1:
inp = samples.clone()
else:
inp = nn.functional.interpolate(samples,
scale_factor=s,
mode='bilinear',
align_corners=False)
feats = model(inp).clone()
if v is None:
v = feats
else:
v += feats
v /= 3
v /= v.norm()
return v