trainer.py

# Copyright Niantic 2020. Patent Pending. All rights reserved.
#
# This software is licensed under the terms of the DepthHints licence
# which allows for non-commercial use only, the full terms of which are made
# available in the LICENSE file.

from __future__ import absolute_import, division, print_function

import numpy as np
import time
import random

import torch
import torch.nn.functional as F
import torch.optim as optim
from torch.utils.data import DataLoader
from tensorboardX import SummaryWriter

import json

from utils import *
from kitti_utils import *
from layers import *

import datasets
import networks
from IPython import embed


class Trainer:
    def __init__(self, options):
        self.opt = options
        self.log_path = os.path.join(self.opt.log_dir, self.opt.model_name)

        # checking height and width are multiples of 32
        assert self.opt.height % 32 == 0, "'height' must be a multiple of 32"
        assert self.opt.width % 32 == 0, "'width' must be a multiple of 32"

        self.models = {}
        self.parameters_to_train = []

        self.device = torch.device("cpu" if self.opt.no_cuda else "cuda")

        self.num_scales = len(self.opt.scales)
        self.num_input_frames = len(self.opt.frame_ids)
        self.num_pose_frames = 2 if self.opt.pose_model_input == "pairs" else self.num_input_frames

        assert self.opt.frame_ids[0] == 0, "frame_ids must start with 0"

        self.use_pose_net = not (self.opt.use_stereo and self.opt.frame_ids == [0])

        if self.opt.use_stereo:
            self.opt.frame_ids.append("s")

        if self.opt.use_depth_hints:
            assert 's' in self.opt.frame_ids, "Can't use depth hints without training from stereo" \
                                              "images - either add --use_stereo or remove " \
                                              "--use_depth_hints."

        self.models["encoder"] = networks.ResnetEncoder(
            self.opt.num_layers, self.opt.weights_init == "pretrained")
        self.models["encoder"].to(self.device)
        self.parameters_to_train += list(self.models["encoder"].parameters())

        self.models["depth"] = networks.DepthDecoder(
            self.models["encoder"].num_ch_enc, self.opt.scales)
        self.models["depth"].to(self.device)
        self.parameters_to_train += list(self.models["depth"].parameters())

        if self.use_pose_net:
            if self.opt.pose_model_type == "separate_resnet":
                self.models["pose_encoder"] = networks.ResnetEncoder(
                    self.opt.num_layers,
                    self.opt.weights_init == "pretrained",
                    num_input_images=self.num_pose_frames)

                self.models["pose_encoder"].to(self.device)
                self.parameters_to_train += list(self.models["pose_encoder"].parameters())

                self.models["pose"] = networks.PoseDecoder(
                    self.models["pose_encoder"].num_ch_enc,
                    num_input_features=1,
                    num_frames_to_predict_for=2)

            elif self.opt.pose_model_type == "shared":
                self.models["pose"] = networks.PoseDecoder(
                    self.models["encoder"].num_ch_enc, self.num_pose_frames)

            elif self.opt.pose_model_type == "posecnn":
                self.models["pose"] = networks.PoseCNN(
                    self.num_input_frames if self.opt.pose_model_input == "all" else 2)

            self.models["pose"].to(self.device)
            self.parameters_to_train += list(self.models["pose"].parameters())

        if self.opt.predictive_mask:
            assert self.opt.disable_automasking, \
                "When using predictive_mask, please disable automasking with --disable_automasking"

            # Our implementation of the predictive masking baseline has the the same architecture
            # as our depth decoder. We predict a separate mask for each source frame.
            self.models["predictive_mask"] = networks.DepthDecoder(
                self.models["encoder"].num_ch_enc, self.opt.scales,
                num_output_channels=(len(self.opt.frame_ids) - 1))
            self.models["predictive_mask"].to(self.device)
            self.parameters_to_train += list(self.models["predictive_mask"].parameters())

        self.model_optimizer = optim.Adam(self.parameters_to_train, self.opt.learning_rate)
        self.model_lr_scheduler = optim.lr_scheduler.StepLR(
            self.model_optimizer, self.opt.scheduler_step_size, 0.1)

        if self.opt.load_weights_folder is not None:
            self.load_model()

        print("Training model named:\n  ", self.opt.model_name)
        print("Models and tensorboard events files are saved to:\n  ", self.opt.log_dir)
        print("Training is using:\n  ", self.device)

        # data
        datasets_dict = {"kitti": datasets.KITTIRAWDataset,
                         "kitti_odom": datasets.KITTIOdomDataset}
        self.dataset = datasets_dict[self.opt.dataset]

        fpath = os.path.join(os.path.dirname(__file__), "splits", self.opt.split, "{}_files.txt")

        train_filenames = readlines(fpath.format("train"))
        val_filenames = readlines(fpath.format("val"))
        img_ext = '.png' if self.opt.png else '.jpg'

        num_train_samples = len(train_filenames)
        self.num_total_steps = num_train_samples // self.opt.batch_size * self.opt.num_epochs

        train_dataset = self.dataset(
            self.opt.data_path, train_filenames, self.opt.height, self.opt.width,
            self.opt.frame_ids, 4, self.opt.use_depth_hints, self.opt.depth_hint_path,
            is_train=True, img_ext=img_ext)
        self.train_loader = DataLoader(
            train_dataset, self.opt.batch_size, True,
            num_workers=self.opt.num_workers, pin_memory=True, drop_last=True)
        val_dataset = self.dataset(
            self.opt.data_path, val_filenames, self.opt.height, self.opt.width,
            self.opt.frame_ids, 4, self.opt.use_depth_hints, self.opt.depth_hint_path,
            is_train=False, img_ext=img_ext)
        self.val_loader = DataLoader(
            val_dataset, self.opt.batch_size, True,
            num_workers=self.opt.num_workers, pin_memory=True, drop_last=True)
        self.val_iter = iter(self.val_loader)

        self.writers = {}
        for mode in ["train", "val"]:
            self.writers[mode] = SummaryWriter(os.path.join(self.log_path, mode))

        if not self.opt.no_ssim:
            self.ssim = SSIM()
            self.ssim.to(self.device)

        self.backproject_depth = {}
        self.project_3d = {}
        for scale in self.opt.scales:
            h = self.opt.height // (2 ** scale)
            w = self.opt.width // (2 ** scale)

            self.backproject_depth[scale] = BackprojectDepth(self.opt.batch_size, h, w)
            self.backproject_depth[scale].to(self.device)

            self.project_3d[scale] = Project3D(self.opt.batch_size, h, w)
            self.project_3d[scale].to(self.device)

        self.depth_metric_names = [
            "de/abs_rel", "de/sq_rel", "de/rms", "de/log_rms", "da/a1", "da/a2", "da/a3"]

        print("Using split:\n  ", self.opt.split)
        print("There are {:d} training items and {:d} validation items\n".format(
            len(train_dataset), len(val_dataset)))

        self.save_opts()

    def set_train(self):
        """Convert all models to training mode
        """
        for m in self.models.values():
            m.train()

    def set_eval(self):
        """Convert all models to testing/evaluation mode
        """
        for m in self.models.values():
            m.eval()

    def train(self):
        """Run the entire training pipeline
        """
        self.epoch = 0
        self.step = 0
        self.start_time = time.time()
        for self.epoch in range(self.opt.num_epochs):
            self.run_epoch()
            if (self.epoch + 1) % self.opt.save_frequency == 0:
                self.save_model()

    def run_epoch(self):
        """Run a single epoch of training and validation
        """
        self.model_lr_scheduler.step()

        print("Training")
        self.set_train()

        for batch_idx, inputs in enumerate(self.train_loader):

            before_op_time = time.time()

            outputs, losses = self.process_batch(inputs)

            self.model_optimizer.zero_grad()
            losses["loss"].backward()
            self.model_optimizer.step()

            duration = time.time() - before_op_time

            # log less frequently after the first 2000 steps to save time & disk space
            early_phase = batch_idx % self.opt.log_frequency == 0 and self.step < 2000
            late_phase = self.step % 2000 == 0

            if early_phase or late_phase:
                self.log_time(batch_idx, duration, losses["loss"].cpu().data)

                if "depth_gt" in inputs:
                    self.compute_depth_losses(inputs, outputs, losses)

                self.log("train", inputs, outputs, losses)
                self.val()

            self.step += 1

    def process_batch(self, inputs):
        """Pass a minibatch through the network and generate images and losses
        """
        for key, ipt in inputs.items():
            inputs[key] = ipt.to(self.device)

        if self.opt.pose_model_type == "shared":
            # If we are using a shared encoder for both depth and pose (as advocated
            # in monodepthv1), then all images are fed separately through the depth encoder.
            all_color_aug = torch.cat([inputs[("color_aug", i, 0)] for i in self.opt.frame_ids])
            all_features = self.models["encoder"](all_color_aug)
            all_features = [torch.split(f, self.opt.batch_size) for f in all_features]

            features = {}
            for i, k in enumerate(self.opt.frame_ids):
                features[k] = [f[i] for f in all_features]

            outputs = self.models["depth"](features[0])
        else:
            # Otherwise, we only feed the image with frame_id 0 through the depth encoder
            features = self.models["encoder"](inputs["color_aug", 0, 0])
            outputs = self.models["depth"](features)

        if self.opt.predictive_mask:
            outputs["predictive_mask"] = self.models["predictive_mask"](features)

        if self.use_pose_net:
            outputs.update(self.predict_poses(inputs, features))

        self.generate_images_pred(inputs, outputs)
        losses = self.compute_losses(inputs, outputs)

        return outputs, losses

    def predict_poses(self, inputs, features):
        """Predict poses between input frames for monocular sequences.
        """
        outputs = {}
        if self.num_pose_frames == 2:
            # In this setting, we compute the pose to each source frame via a
            # separate forward pass through the pose network.

            # select what features the pose network takes as input
            if self.opt.pose_model_type == "shared":
                pose_feats = {f_i: features[f_i] for f_i in self.opt.frame_ids}
            else:
                pose_feats = {f_i: inputs["color_aug", f_i, 0] for f_i in self.opt.frame_ids}

            for f_i in self.opt.frame_ids[1:]:
                if f_i != "s":
                    # To maintain ordering we always pass frames in temporal order
                    if f_i < 0:
                        pose_inputs = [pose_feats[f_i], pose_feats[0]]
                    else:
                        pose_inputs = [pose_feats[0], pose_feats[f_i]]

                    if self.opt.pose_model_type == "separate_resnet":
                        pose_inputs = [self.models["pose_encoder"](torch.cat(pose_inputs, 1))]
                    elif self.opt.pose_model_type == "posecnn":
                        pose_inputs = torch.cat(pose_inputs, 1)

                    axisangle, translation = self.models["pose"](pose_inputs)
                    outputs[("axisangle", 0, f_i)] = axisangle
                    outputs[("translation", 0, f_i)] = translation

                    # Invert the matrix if the frame id is negative
                    outputs[("cam_T_cam", 0, f_i)] = transformation_from_parameters(
                        axisangle[:, 0], translation[:, 0], invert=(f_i < 0))

        else:
            # Here we input all frames to the pose net (and predict all poses) together
            if self.opt.pose_model_type in ["separate_resnet", "posecnn"]:
                pose_inputs = torch.cat(
                    [inputs[("color_aug", i, 0)] for i in self.opt.frame_ids if i != "s"], 1)

                if self.opt.pose_model_type == "separate_resnet":
                    pose_inputs = [self.models["pose_encoder"](pose_inputs)]

            elif self.opt.pose_model_type == "shared":
                pose_inputs = [features[i] for i in self.opt.frame_ids if i != "s"]

            axisangle, translation = self.models["pose"](pose_inputs)

            for i, f_i in enumerate(self.opt.frame_ids[1:]):
                if f_i != "s":
                    outputs[("axisangle", 0, f_i)] = axisangle
                    outputs[("translation", 0, f_i)] = translation
                    outputs[("cam_T_cam", 0, f_i)] = transformation_from_parameters(
                        axisangle[:, i], translation[:, i])

        return outputs

    def val(self):
        """Validate the model on a single minibatch
        """
        self.set_eval()
        try:
            inputs = self.val_iter.next()
        except StopIteration:
            self.val_iter = iter(self.val_loader)
            inputs = self.val_iter.next()

        with torch.no_grad():
            outputs, losses = self.process_batch(inputs)

            if "depth_gt" in inputs:
                self.compute_depth_losses(inputs, outputs, losses)

            self.log("val", inputs, outputs, losses)
            del inputs, outputs, losses

        self.set_train()

    def generate_images_pred(self, inputs, outputs):
        """Generate the warped (reprojected) color images for a minibatch.
        Generated images are saved into the `outputs` dictionary.
        """
        for scale in self.opt.scales:
            disp = outputs[("disp", scale)]
            if self.opt.v1_multiscale:
                source_scale = scale
            else:
                disp = F.interpolate(
                    disp, [self.opt.height, self.opt.width], mode="bilinear", align_corners=False)
                source_scale = 0

            _, depth = disp_to_depth(disp, self.opt.min_depth, self.opt.max_depth)

            outputs[("depth", 0, scale)] = depth

            for i, frame_id in enumerate(self.opt.frame_ids[1:]):

                if frame_id == "s":
                    T = inputs["stereo_T"]
                else:
                    T = outputs[("cam_T_cam", 0, frame_id)]

                # from the authors of https://arxiv.org/abs/1712.00175
                if self.opt.pose_model_type == "posecnn":

                    axisangle = outputs[("axisangle", 0, frame_id)]
                    translation = outputs[("translation", 0, frame_id)]

                    inv_depth = 1 / depth
                    mean_inv_depth = inv_depth.mean(3, True).mean(2, True)

                    T = transformation_from_parameters(
                        axisangle[:, 0], translation[:, 0] * mean_inv_depth[:, 0], frame_id < 0)

                cam_points = self.backproject_depth[source_scale](
                    depth, inputs[("inv_K", source_scale)])
                pix_coords = self.project_3d[source_scale](
                    cam_points, inputs[("K", source_scale)], T)

                outputs[("sample", frame_id, scale)] = pix_coords

                outputs[("color", frame_id, scale)] = F.grid_sample(
                    inputs[("color", frame_id, source_scale)],
                    outputs[("sample", frame_id, scale)],
                    padding_mode="border")

                if not self.opt.disable_automasking:
                    outputs[("color_identity", frame_id, scale)] = \
                        inputs[("color", frame_id, source_scale)]

                if self.opt.use_depth_hints:
                    if self.opt.v1_multiscale:
                        raise NotImplementedError("Depth hints are currently not implemented for v1"
                                                  "multiscale, please remove --v1_multiscape flag ")

                    elif frame_id == 's' and scale == 0:
                        # generate depth hint warped image (only max scale and for stereo image)
                        depth = inputs['depth_hint']
                        cam_points = self.backproject_depth[source_scale](
                            depth, inputs[("inv_K", source_scale)])
                        pix_coords = self.project_3d[source_scale](
                            cam_points, inputs[("K", source_scale)], T)

                        outputs[("color_depth_hint", frame_id, scale)] = F.grid_sample(
                            inputs[("color", frame_id, source_scale)],
                            pix_coords, padding_mode="border")

    def compute_reprojection_loss(self, pred, target):
        """Computes reprojection loss between a batch of predicted and target images
        """
        abs_diff = torch.abs(target - pred)
        l1_loss = abs_diff.mean(1, True)

        if self.opt.no_ssim:
            reprojection_loss = l1_loss
        else:
            ssim_loss = self.ssim(pred, target).mean(1, True)
            reprojection_loss = 0.85 * ssim_loss + 0.15 * l1_loss

        return reprojection_loss

    @staticmethod
    def compute_proxy_supervised_loss(pred, target, valid_pixels, loss_mask):
        """ Compute proxy supervised loss (depth hint loss) for prediction.

            - valid_pixels is a mask of valid depth hint pixels (i.e. non-zero depth values).
            - loss_mask is a mask of where to apply the proxy supervision (i.e. the depth hint gave
            the smallest reprojection error)"""

        # first compute proxy supervised loss for all valid pixels
        depth_hint_loss = torch.log(torch.abs(target - pred) + 1) * valid_pixels

        # only keep pixels where depth hints reprojection loss is smallest
        depth_hint_loss = depth_hint_loss * loss_mask

        return depth_hint_loss

    @staticmethod
    def compute_loss_masks(reprojection_loss, identity_reprojection_loss,
                           depth_hint_reprojection_loss):
        """ Compute loss masks for each of standard reprojection and depth hint
        reprojection.

        identity_reprojections_loss and/or depth_hint_reprojection_loss can be None"""

        if identity_reprojection_loss is None:
            # we are not using automasking - standard reprojection loss applied to all pixels
            reprojection_loss_mask = torch.ones_like(reprojection_loss)

            if depth_hint_reprojection_loss:
                all_losses = torch.cat([reprojection_loss, depth_hint_reprojection_loss], dim=1)
                idxs = torch.argmin(all_losses, dim=1, keepdim=True)
                depth_hint_loss_mask = (idxs == 1).float()

        else:
            # we are using automasking
            if depth_hint_reprojection_loss is not None:
                all_losses = torch.cat([reprojection_loss, identity_reprojection_loss,
                                        depth_hint_reprojection_loss], dim=1)
            else:
                all_losses = torch.cat([reprojection_loss, identity_reprojection_loss], dim=1)

            idxs = torch.argmin(all_losses, dim=1, keepdim=True)
            reprojection_loss_mask = (idxs != 1).float()  # automask has index '1'
            depth_hint_loss_mask = (idxs == 2).float()  # will be zeros if not using depth hints

        # just set depth hint mask to None if not using depth hints
        depth_hint_loss_mask = \
            None if depth_hint_reprojection_loss is None else depth_hint_loss_mask

        return reprojection_loss_mask, depth_hint_loss_mask

    def compute_losses(self, inputs, outputs):
        """Compute the reprojection, smoothness and proxy supervised losses for a minibatch
        """
        losses = {}
        total_loss = 0

        # compute depth hint reprojection loss
        if self.opt.use_depth_hints:
            pred = outputs[("color_depth_hint", 's', 0)]
            depth_hint_reproj_loss = self.compute_reprojection_loss(pred, inputs[("color", 0, 0)])
            # set loss for missing pixels to be high so they are never chosen as minimum
            depth_hint_reproj_loss += 1000 * (1 - inputs['depth_hint_mask'])
        else:
            depth_hint_reproj_loss = None

        for scale in self.opt.scales:
            loss = 0
            reprojection_losses = []

            if self.opt.v1_multiscale:
                source_scale = scale
            else:
                source_scale = 0

            disp = outputs[("disp", scale)]
            color = inputs[("color", 0, scale)]
            target = inputs[("color", 0, source_scale)]

            for frame_id in self.opt.frame_ids[1:]:
                pred = outputs[("color", frame_id, scale)]
                reprojection_losses.append(self.compute_reprojection_loss(pred, target))

            reprojection_losses = torch.cat(reprojection_losses, 1)

            if not self.opt.disable_automasking:
                identity_reprojection_losses = []
                for frame_id in self.opt.frame_ids[1:]:
                    pred = inputs[("color", frame_id, source_scale)]
                    identity_reprojection_losses.append(
                        self.compute_reprojection_loss(pred, target))

                identity_reprojection_losses = torch.cat(identity_reprojection_losses, 1)

                if self.opt.avg_reprojection:
                    identity_reprojection_loss = identity_reprojection_losses.mean(1, keepdim=True)
                else:
                    # differently to Monodepth2, compute mins as we go
                    identity_reprojection_loss, _ = torch.min(identity_reprojection_losses, dim=1,
                                                              keepdim=True)
            else:
                identity_reprojection_loss = None
                if self.opt.predictive_mask:
                    # use the predicted mask
                    mask = outputs["predictive_mask"]["disp", scale]
                    if not self.opt.v1_multiscale:
                        mask = F.interpolate(
                            mask, [self.opt.height, self.opt.width],
                            mode="bilinear", align_corners=False)

                    reprojection_losses *= mask

                    # add a loss pushing mask to 1 (using nn.BCELoss for stability)
                    weighting_loss = 0.2 * nn.BCELoss()(mask, torch.ones(mask.shape).cuda())
                    loss += weighting_loss.mean()

            if self.opt.avg_reprojection:
                reprojection_loss = reprojection_losses.mean(1, keepdim=True)
            else:
                # differently to Monodepth2, compute mins as we go
                reprojection_loss, _ = torch.min(reprojection_losses, dim=1, keepdim=True)

            if not self.opt.disable_automasking:
                # add random numbers to break ties
                identity_reprojection_loss += torch.randn(
                    identity_reprojection_loss.shape).cuda() * 0.00001

            # find minimum losses from [reprojection, identity, depth hints reprojection]
            reprojection_loss_mask, depth_hint_loss_mask = \
                self.compute_loss_masks(reprojection_loss,
                                        identity_reprojection_loss,
                                        depth_hint_reproj_loss)

            # standard reprojection loss
            reprojection_loss = reprojection_loss * reprojection_loss_mask
            reprojection_loss = reprojection_loss.sum() / (reprojection_loss_mask.sum() + 1e-7)

            outputs["identity_selection/{}".format(scale)] = (1 - reprojection_loss_mask).float()
            losses['reproj_loss/{}'.format(scale)] = reprojection_loss

            # proxy supervision loss
            depth_hint_loss = 0
            if self.opt.use_depth_hints:
                target = inputs['depth_hint']
                pred = outputs[('depth', 0, scale)]
                valid_pixels = inputs['depth_hint_mask']

                depth_hint_loss = self.compute_proxy_supervised_loss(pred, target, valid_pixels,
                                                                     depth_hint_loss_mask)
                depth_hint_loss = depth_hint_loss.sum() / (depth_hint_loss_mask.sum() + 1e-7)
                # save for logging
                outputs["depth_hint_pixels/{}".format(scale)] = depth_hint_loss_mask
                losses['depth_hint_loss/{}'.format(scale)] = depth_hint_loss

            loss += reprojection_loss + depth_hint_loss

            mean_disp = disp.mean(2, True).mean(3, True)
            norm_disp = disp / (mean_disp + 1e-7)
            smooth_loss = get_smooth_loss(norm_disp, color)

            loss += self.opt.disparity_smoothness * smooth_loss / (2 ** scale)
            total_loss += loss
            losses["loss/{}".format(scale)] = loss

        total_loss /= self.num_scales
        losses["loss"] = total_loss

        return losses

    def compute_depth_losses(self, inputs, outputs, losses):
        """Compute depth metrics, to allow monitoring during training

        This isn't particularly accurate as it averages over the entire batch,
        so is only used to give an indication of validation performance
        """
        depth_pred = outputs[("depth", 0, 0)]
        depth_pred = torch.clamp(F.interpolate(
            depth_pred, [375, 1242], mode="bilinear", align_corners=False), 1e-3, 80)
        depth_pred = depth_pred.detach()

        depth_gt = inputs["depth_gt"]
        mask = depth_gt > 0

        # garg/eigen crop
        crop_mask = torch.zeros_like(mask)
        crop_mask[:, :, 153:371, 44:1197] = 1
        mask = mask * crop_mask

        depth_gt = depth_gt[mask]
        depth_pred = depth_pred[mask]
        depth_pred *= torch.median(depth_gt) / torch.median(depth_pred)

        depth_pred = torch.clamp(depth_pred, min=1e-3, max=80)

        depth_errors = compute_depth_errors(depth_gt, depth_pred)

        for i, metric in enumerate(self.depth_metric_names):
            losses[metric] = np.array(depth_errors[i].cpu())

    def log_time(self, batch_idx, duration, loss):
        """Print a logging statement to the terminal
        """
        samples_per_sec = self.opt.batch_size / duration
        time_sofar = time.time() - self.start_time
        training_time_left = (
            self.num_total_steps / self.step - 1.0) * time_sofar if self.step > 0 else 0
        print_string = "epoch {:>3} | batch {:>6} | examples/s: {:5.1f}" + \
            " | loss: {:.5f} | time elapsed: {} | time left: {}"
        print(print_string.format(self.epoch, batch_idx, samples_per_sec, loss,
                                  sec_to_hm_str(time_sofar), sec_to_hm_str(training_time_left)))

    def log(self, mode, inputs, outputs, losses):
        """Write an event to the tensorboard events file
        """
        writer = self.writers[mode]
        for l, v in losses.items():
            writer.add_scalar("{}".format(l), v, self.step)

        for j in range(min(4, self.opt.batch_size)):  # write a maxmimum of four images
            for s in self.opt.scales:
                for frame_id in self.opt.frame_ids:
                    writer.add_image(
                        "color_{}_{}/{}".format(frame_id, s, j),
                        inputs[("color", frame_id, s)][j].data, self.step)
                    if s == 0 and frame_id != 0:
                        writer.add_image(
                            "color_pred_{}_{}/{}".format(frame_id, s, j),
                            outputs[("color", frame_id, s)][j].data, self.step)

                writer.add_image(
                    "disp_{}/{}".format(s, j),
                    normalize_image(outputs[("disp", s)][j]), self.step)

                if self.opt.predictive_mask:
                    for f_idx, frame_id in enumerate(self.opt.frame_ids[1:]):
                        writer.add_image(
                            "predictive_mask_{}_{}/{}".format(frame_id, s, j),
                            outputs["predictive_mask"][("disp", s)][j, f_idx][None, ...],
                            self.step)

                elif not self.opt.disable_automasking:
                    writer.add_image(
                        "automask_{}/{}".format(s, j),
                        outputs["identity_selection/{}".format(s)][j][None, ...], self.step)

                # depth hint logging
                if self.opt.use_depth_hints:
                    if s == 0:
                        disp = 1 / (inputs['depth_hint'] + 1e-7) * inputs['depth_hint_mask']
                        writer.add_image(
                            "depth_hint/{}".format(j),
                            normalize_image(disp[j]), self.step)

                        writer.add_image(
                            "depth_hint_pixels_{}/{}".format(s, j),
                            outputs["depth_hint_pixels/{}".format(s)][j][None, ...], self.step)

    def save_opts(self):
        """Save options to disk so we know what we ran this experiment with
        """
        models_dir = os.path.join(self.log_path, "models")
        if not os.path.exists(models_dir):
            os.makedirs(models_dir)
        to_save = self.opt.__dict__.copy()

        with open(os.path.join(models_dir, 'opt.json'), 'w') as f:
            json.dump(to_save, f, indent=2)

    def save_model(self):
        """Save model weights to disk
        """
        save_folder = os.path.join(self.log_path, "models", "weights_{}".format(self.epoch))
        if not os.path.exists(save_folder):
            os.makedirs(save_folder)

        for model_name, model in self.models.items():
            save_path = os.path.join(save_folder, "{}.pth".format(model_name))
            to_save = model.state_dict()
            if model_name == 'encoder':
                # save the sizes - these are needed at prediction time
                to_save['height'] = self.opt.height
                to_save['width'] = self.opt.width
                to_save['use_stereo'] = self.opt.use_stereo
            torch.save(to_save, save_path)

        save_path = os.path.join(save_folder, "{}.pth".format("adam"))
        torch.save(self.model_optimizer.state_dict(), save_path)

    def load_model(self):
        """Load model(s) from disk
        """
        self.opt.load_weights_folder = os.path.expanduser(self.opt.load_weights_folder)

        assert os.path.isdir(self.opt.load_weights_folder), \
            "Cannot find folder {}".format(self.opt.load_weights_folder)
        print("loading model from folder {}".format(self.opt.load_weights_folder))

        for n in self.opt.models_to_load:
            print("Loading {} weights...".format(n))
            path = os.path.join(self.opt.load_weights_folder, "{}.pth".format(n))
            model_dict = self.models[n].state_dict()
            pretrained_dict = torch.load(path)
            pretrained_dict = {k: v for k, v in pretrained_dict.items() if k in model_dict}
            model_dict.update(pretrained_dict)
            self.models[n].load_state_dict(model_dict)

        # loading adam state
        optimizer_load_path = os.path.join(self.opt.load_weights_folder, "adam.pth")
        if os.path.isfile(optimizer_load_path):
            print("Loading Adam weights")
            optimizer_dict = torch.load(optimizer_load_path)
            self.model_optimizer.load_state_dict(optimizer_dict)
        else:
            print("Cannot find Adam weights so Adam is randomly initialized")