cubercnn/modeling/meta_arch/rcnn3d.py

# Copyright (c) Meta Platforms, Inc. and affiliates
import logging
from typing import Dict, List, Optional
from detectron2.layers import move_device_like
from detectron2.structures.image_list import ImageList
import torch
import numpy as np
from detectron2.layers import ShapeSpec, batched_nms
from detectron2.utils.visualizer import Visualizer
from detectron2.data.detection_utils import convert_image_to_rgb
from detectron2.structures import Instances
from detectron2.utils.events import get_event_storage
from detectron2.data import MetadataCatalog

from detectron2.modeling.backbone import Backbone, BACKBONE_REGISTRY
from detectron2.modeling.proposal_generator import build_proposal_generator
from detectron2.utils.logger import _log_api_usage
from detectron2.modeling.meta_arch import (
    META_ARCH_REGISTRY, GeneralizedRCNN
)
# from cubercnn.data.generate_depth_maps import setup_depth_model
from cubercnn.modeling.roi_heads import build_roi_heads

from detectron2.data import MetadataCatalog
from cubercnn.modeling.roi_heads import build_roi_heads
from cubercnn import util, vis
import torch.nn.functional as F
from detectron2.config import configurable
import torch.nn as nn

logger = logging.getLogger(__name__)


@META_ARCH_REGISTRY.register()
class RCNN3D(GeneralizedRCNN):
    
    @classmethod
    def from_config(cls, cfg, priors=None):
        backbone = build_backbone(cfg, priors=priors)
        return {
            "backbone": backbone,
            "proposal_generator": build_proposal_generator(cfg, backbone.output_shape()),
            "roi_heads": build_roi_heads(cfg, backbone.output_shape(), priors=priors),
            "input_format": cfg.INPUT.FORMAT,
            "vis_period": cfg.VIS_PERIOD,
            "pixel_mean": cfg.MODEL.PIXEL_MEAN,
            "pixel_std": cfg.MODEL.PIXEL_STD,
        }

    def forward(self, batched_inputs: List[Dict[str, torch.Tensor]]):
        
        if not self.training:
            return self.inference(batched_inputs)

        images = self.preprocess_image(batched_inputs)

        # scaling factor for the sample relative to its original scale
        # e.g., how much has the image been upsampled by? or downsampled?
        im_scales_ratio = [info['height'] / im.shape[1] for (info, im) in zip(batched_inputs, images)]

        # The unmodified intrinsics for the image
        Ks = [torch.FloatTensor(info['K']) for info in batched_inputs]

        if "instances" in batched_inputs[0]:
            gt_instances = [x["instances"].to(self.device) for x in batched_inputs]
        else:
            gt_instances = None

        # the backbone is actually a FPN, where the DLA model is the bottom-up structure.
        # FPN: https://arxiv.org/abs/1612.03144v2
        # backbone and proposal generator only work on 2D images and annotations.
        features = self.backbone(images.tensor)
        proposals, proposal_losses = self.proposal_generator(images, features, gt_instances)

        instances, detector_losses = self.roi_heads(
            images, features, proposals, 
            Ks, im_scales_ratio, 
            gt_instances
        )

        if self.vis_period > 0:
            storage = get_event_storage()
            if storage.iter % self.vis_period == 0 and storage.iter > 0:
                self.visualize_training(batched_inputs, proposals, instances)

        losses = {}
        losses.update(detector_losses)
        losses.update(proposal_losses)
        return losses

    def inference(
        self,
        batched_inputs: List[Dict[str, torch.Tensor]],
        detected_instances: Optional[List[Instances]] = None,
        do_postprocess: bool = True,
    ):
        assert not self.training

        images = self.preprocess_image(batched_inputs)

        # scaling factor for the sample relative to its original scale
        # e.g., how much has the image been upsampled by? or downsampled?
        im_scales_ratio = [info['height'] / im.shape[1] for (info, im) in zip(batched_inputs, images)]
        
        # The unmodified intrinsics for the image
        Ks = [torch.FloatTensor(info['K']) for info in batched_inputs]

        features = self.backbone(images.tensor)

        # Pass oracle 2D boxes into the RoI heads
        if type(batched_inputs == list) and np.any(['oracle2D' in b for b in batched_inputs]):
            oracles = [b['oracle2D'] for b in batched_inputs]
            results, _ = self.roi_heads(images, features, oracles, Ks, im_scales_ratio, None)
        
        # normal inference
        else:
            proposals, _ = self.proposal_generator(images, features, None)
            results, _ = self.roi_heads(images, features, proposals, Ks, im_scales_ratio, None)
            
        if do_postprocess:
            assert not torch.jit.is_scripting(), "Scripting is not supported for postprocess."
            return GeneralizedRCNN._postprocess(results, batched_inputs, images.image_sizes)
        else:
            return results

    def visualize_training(self, batched_inputs, proposals, instances):
        """
        A function used to visualize images and proposals. It shows ground truth
        bounding boxes on the original image and up to 20 top-scoring predicted
        object proposals on the original image. Users can implement different
        visualization functions for different models.
        Args:
            batched_inputs (list): a list that contains input to the model.
            proposals (list): a list that contains predicted proposals. Both
                batched_inputs and proposals should have the same length.
            instances (list): a list that contains predicted RoIhead instances. Both
                batched_inputs and proposals should have the same length.
        """
        
        storage = get_event_storage()

        # minimum number of boxes to try to visualize per image
        max_vis_prop = 20

        if not hasattr(self, 'thing_classes'):
            self.thing_classes = MetadataCatalog.get('omni3d_model').thing_classes
            self.num_classes = len(self.thing_classes)

        # make a dummy for 2d scenario
        only2d = instances is None
        if only2d:
            instances = [None]*len(batched_inputs)

        for input, prop, instances_i in zip(batched_inputs, proposals, instances):

            img = input["image"]            
            img = convert_image_to_rgb(img.permute(1, 2, 0), self.input_format)
            img_3DGT = np.ascontiguousarray(img.copy()[:, :, [2, 1, 1]]) # BGR
            img_3DPR = np.ascontiguousarray(img.copy()[:, :, [2, 1, 1]]) # BGR

            '''
            Visualize the 2D GT and proposal predictions
            '''
            v_gt = Visualizer(img, None)
            v_gt = v_gt.overlay_instances(boxes=input["instances"].gt_boxes)
            anno_img = v_gt.get_image()
            box_size = min(len(prop.proposal_boxes), max_vis_prop)
            v_pred = Visualizer(img, None)
            v_pred = v_pred.overlay_instances(
                boxes=prop.proposal_boxes[0:box_size].tensor.cpu().numpy()
            )
            prop_img = v_pred.get_image()
            vis_img_rpn = np.concatenate((anno_img, prop_img), axis=1)
            vis_img_rpn = vis_img_rpn.transpose(2, 0, 1)
            storage.put_image("Left: GT 2D bounding boxes; Right: Predicted 2D proposals", vis_img_rpn)
            if only2d:
                break
            '''
            Visualize the 3D GT and predictions
            '''
            K = torch.tensor(input['K'], device=self.device)
            scale = input['height']/img.shape[0]
            fx, sx = (val.item()/scale for val in K[0, [0, 2]])
            fy, sy = (val.item()/scale for val in K[1, [1, 2]])
            
            K_scaled = torch.tensor(
                [[1/scale, 0 , 0], [0, 1/scale, 0], [0, 0, 1.0]], 
                dtype=torch.float32, device=self.device
            ) @ K

            gts_per_image = input["instances"]

            gt_classes = gts_per_image.gt_classes
            
            # Filter out irrelevant groundtruth
            fg_selection_mask = (gt_classes != -1) & (gt_classes < self.num_classes)

            gt_classes = gt_classes[fg_selection_mask]
            gt_class_names = [self.thing_classes[cls_idx] for cls_idx in gt_classes]
            gt_boxes   = gts_per_image.gt_boxes.tensor[fg_selection_mask]  # 2D boxes
            gt_poses   = gts_per_image.gt_poses[fg_selection_mask]         # GT poses

            # projected 2D center, depth, w, h, l, 3D center
            gt_boxes3D = gts_per_image.gt_boxes3D[fg_selection_mask]

            # this box may have been mirrored and scaled so
            # we need to recompute XYZ in 3D by backprojecting.
            gt_z = gt_boxes3D[:, 2]

            gt_x3D = gt_z * (gt_boxes3D[:, 0] - sx)/fx
            gt_y3D = gt_z * (gt_boxes3D[:, 1] - sy)/fy
            
            # put together the GT boxes
            gt_center_3D = torch.stack((gt_x3D, gt_y3D, gt_z)).T
            gt_boxes3D_XYZ_WHL = torch.cat((gt_center_3D, gt_boxes3D[:, 3:6]), dim=1)

            gt_colors = torch.tensor(
                [util.get_color(i) for i in range(len(gt_boxes3D_XYZ_WHL))], 
                device=self.device
            )/255.0

            gt_meshes = util.mesh_cuboid(gt_boxes3D_XYZ_WHL, gt_poses, gt_colors)

            # perform a simple NMS, which is not cls dependent. 
            keep = batched_nms(
                instances_i.pred_boxes.tensor, 
                instances_i.scores, 
                torch.zeros(len(instances_i.scores), dtype=torch.long, device=instances_i.scores.device), 
                self.roi_heads.box_predictor.test_nms_thresh
            )
            
            keep = keep[:max_vis_prop]
            num_to_visualize = len(keep)

            pred_xyzwhl = torch.cat((instances_i.pred_center_cam[keep], instances_i.pred_dimensions[keep]), dim=1)
            pred_pose = instances_i.pred_pose[keep]

            pred_colors = torch.tensor(
                [util.get_color(i) for i in range(num_to_visualize)], 
                device=self.device
            )/255.0

            pred_boxes = instances_i.pred_boxes[keep]
            pred_scores = instances_i.scores[keep]
            pred_classes = instances_i.pred_classes[keep]
            pred_class_names = ['{} {:.2f}'.format(self.thing_classes[cls_idx], score) for cls_idx, score in zip(pred_classes, pred_scores)]
            pred_meshes = util.mesh_cuboid(pred_xyzwhl, pred_pose, pred_colors)

            # convert to lists
            pred_meshes = [pred_meshes.__getitem__(i).detach() for i in range(len(pred_meshes))]
            gt_meshes = [gt_meshes.__getitem__(i) for i in range(len(gt_meshes))]

            img_3DPR = vis.draw_scene_view(img_3DPR, K_scaled.cpu().numpy(), pred_meshes, text=pred_class_names, mode='front', blend_weight=0.0, blend_weight_overlay=0.85)
            img_3DGT = vis.draw_scene_view(img_3DGT, K_scaled.cpu().numpy(), gt_meshes, text=gt_class_names, mode='front', blend_weight=0.0, blend_weight_overlay=0.85)

            # horizontal stack 3D GT and pred left/right
            vis_img_3d = np.concatenate((img_3DGT, img_3DPR), axis=1)
            vis_img_3d = vis_img_3d[:, :, [2, 1, 0]] # RGB
            vis_img_3d = vis_img_3d.astype(np.uint8).transpose(2, 0, 1)

            storage.put_image("Left: GT 3D cuboids; Right: Predicted 3D cuboids", vis_img_3d)

            break  # only visualize one image in a batch

@META_ARCH_REGISTRY.register()
class RCNN3D_combined_features(nn.Module):

    @configurable
    def __init__(self, *, backbone, proposal_generator, roi_heads, input_format, vis_period, pixel_mean, pixel_std, depth_model, only_2d):
        super().__init__()
        self.backbone = backbone
        self.proposal_generator = proposal_generator
        self.roi_heads = roi_heads
        self.input_format = input_format
        self.vis_period = vis_period
        self.depth_model = depth_model
        self.only_2d = only_2d

        self.register_buffer("pixel_mean", torch.tensor(pixel_mean).view(-1, 1, 1), False)
        self.register_buffer("pixel_std", torch.tensor(pixel_std).view(-1, 1, 1), False)
        assert (
            self.pixel_mean.shape == self.pixel_std.shape
        ), f"{self.pixel_mean} and {self.pixel_std} have different shapes!"

    @classmethod
    def from_config(cls, cfg, priors=None):
        backbone = build_backbone(cfg, priors=priors)
        if False: # some leftover from experimenting with incorporating depth features
            depth_model = 'zoedepth'
            pretrained_resource = 'local::depth/checkpoints/depth_anything_metric_depth_indoor.pt'
            d_model = setup_depth_model(depth_model, pretrained_resource) #NOTE maybe make the depth model be learnable as well
        
            shape_modified = {key:ShapeSpec(i.channels*2,stride=i.stride) for key, i in backbone.output_shape().items()}
        else:
            d_model = None
            shape_modified = backbone.output_shape()

        return {
            "backbone": backbone,
            "proposal_generator": build_proposal_generator(cfg, backbone.output_shape()),
            "roi_heads": build_roi_heads(cfg, shape_modified, priors=priors),
            "input_format": cfg.INPUT.FORMAT,
            "vis_period": cfg.VIS_PERIOD,
            "pixel_mean": cfg.MODEL.PIXEL_MEAN,
            "pixel_std": cfg.MODEL.PIXEL_STD,
            "depth_model": d_model,
            "only_2d": cfg.MODEL.ROI_CUBE_HEAD.LOSS_W_3D == 0.0,
        }
    
                
    @property
    def device(self):
        return self.pixel_mean.device

    def _move_to_current_device(self, x):
        return move_device_like(x, self.pixel_mean)


    def preprocess_image(self, batched_inputs: List[Dict[str, torch.Tensor]], normalise=True, img_type="image", convert=False, NoOp=False, to_float=False):
        """
        Normalize, pad and batch the input images.
        """
        images = [self._move_to_current_device(x[img_type]) for x in batched_inputs]
        if normalise:
            images = [(x - self.pixel_mean) / self.pixel_std for x in images]
        if convert:
            # convert from BGR to RGB
            images = [x[[2,1,0],:,:] for x in images]
        if to_float:
            images = [x.float()/255.0 for x in images]
        if NoOp:
            images = ImageList.from_tensors(images)
            return images
        images = ImageList.from_tensors(
            images,
            self.backbone.size_divisibility,
            padding_constraints=self.backbone.padding_constraints,
        )
        return images

    def _standardize(self, x:torch.Tensor, y:torch.Tensor):
        '''standardise x to match the mean and std of y'''
        ym = y.mean()
        ys = y.std()
        xm = x.mean()
        xs = x.std()
        return (x - xm) * (ys / xs) + ym
    
    def cat_depth_features(self, features, images_raw):
        pred_o = self.depth_model(images_raw.tensor.float()/255.0)
        # depth features corresponding to p2, p3, p4, p5

        d_features = pred_o['depth_features']
        # img_features = features['p5']
        # we must scale the depth map to the same size as the conv feature, otherwise the scale will not correspond correctly in the roi pooling
        for (layer, img_feature), d_feature in zip(features.items(), reversed(d_features)):
            d_feature = F.interpolate(d_feature, size=img_feature.shape[-2:], mode='bilinear', align_corners=True)
            d_feature = self._standardize(d_feature, img_feature)
            features[layer] = torch.cat((img_feature, d_feature), dim=1)
        return features

    def forward(self, batched_inputs: List[Dict[str, torch.Tensor]]):
        
        if not self.training:
            return self.inference(batched_inputs) # segmentor is just none in inference because we dont need the loss

        images = self.preprocess_image(batched_inputs)
        # NOTE: images_raw are scaled to be padded to the same size as the largest. 
        # This is necessary because the images are of different sizes, so to batch them they must each be the same size.
        images_raw = self.preprocess_image(batched_inputs, img_type='image', convert=True, normalise=False, NoOp=True)
        # if we want depth maps they are there
        if not self.only_2d:
            depth_maps = self.preprocess_image(batched_inputs, img_type="depth_map", normalise=False, NoOp=True)

            ground_maps_fail = [i['ground_map'] is None for i in batched_inputs]
            ground_maps_fail_idx = [i for i, x in enumerate(ground_maps_fail) if x]
            for idx in ground_maps_fail_idx:
                batched_inputs[idx]['ground_map'] = torch.tensor([[1]]) # make a dummy to indicate a fail
            ground_maps = self.preprocess_image(batched_inputs, img_type="ground_map", normalise=False, NoOp=True)
        else:
            ground_maps = None
            depth_maps = None

        # scaling factor for the sample relative to its original scale
        # e.g., how much has the image been upsampled by? or downsampled?
        im_scales_ratio = [info['height'] / im.shape[1] for (info, im) in zip(batched_inputs, images)]

        # The unmodified intrinsics for the image
        Ks = [torch.FloatTensor(info['K']) for info in batched_inputs]

        if "instances" in batched_inputs[0]:
            gt_instances = [x["instances"].to(self.device) for x in batched_inputs]

        features = self.backbone(images.tensor)
        proposals, proposal_losses = self.proposal_generator(images, features, gt_instances)

        if self.depth_model is not None:
            features = self.cat_depth_features(features, images_raw)
        
        instances, detector_losses = self.roi_heads(
            images, images_raw, ground_maps, depth_maps, features, proposals, 
            Ks, im_scales_ratio,
            gt_instances
        )

        if self.vis_period > 0:
            storage = get_event_storage()
            if storage.iter % self.vis_period == 0 and storage.iter > 0:
                self.visualize_training(batched_inputs, proposals, instances)

        losses = {}
        losses.update(detector_losses)
        losses.update(proposal_losses)
        return losses
    
    def inference(
        self,
        batched_inputs: List[Dict[str, torch.Tensor]], 
        detected_instances: Optional[List[Instances]] = None,
        do_postprocess: bool = True,
    ):
        assert not self.training

        images = self.preprocess_image(batched_inputs)
        images_raw = self.preprocess_image(batched_inputs, img_type='image', convert=True, normalise=False, NoOp=True)
        # do we assume no access to ground maps in inference?
        ground_maps = None
        depth_maps = None

        # scaling factor for the sample relative to its original scale
        # e.g., how much has the image been upsampled by? or downsampled?
        im_scales_ratio = [info['height'] / im.shape[1] for (info, im) in zip(batched_inputs, images)]
        
        # The unmodified intrinsics for the image
        Ks = [torch.FloatTensor(info['K']) for info in batched_inputs]

        features = self.backbone(images.tensor)

        # Pass oracle 2D boxes into the RoI heads
        if type(batched_inputs == list) and np.any(['oracle2D' in b for b in batched_inputs]):
            oracles = [b['oracle2D'] for b in batched_inputs]
            results, _ = self.roi_heads(images, images_raw, ground_maps, depth_maps, features, oracles, Ks, im_scales_ratio, None)
        
        # normal inference
        else:
            proposals, _ = self.proposal_generator(images, features, None)
            if self.depth_model is not None:
                features = self.cat_depth_features(features, images_raw)
            # pred boxes are proposals
            results, _ = self.roi_heads(images, images_raw, ground_maps, depth_maps, features, proposals, Ks, im_scales_ratio, None)
            
        if do_postprocess:
            assert not torch.jit.is_scripting(), "Scripting is not supported for postprocess."
            return GeneralizedRCNN._postprocess(results, batched_inputs, images.image_sizes)
        else:
            return results

    def visualize_training(self, batched_inputs, proposals, instances):
        """
        A function used to visualize images and proposals. It shows ground truth
        bounding boxes on the original image and up to 20 top-scoring predicted
        object proposals on the original image. Users can implement different
        visualization functions for different models.
        Args:
            batched_inputs (list): a list that contains input to the model.
            proposals (list): a list that contains predicted proposals. Both
                batched_inputs and proposals should have the same length.
            instances (list): a list that contains predicted RoIhead instances. Both
                batched_inputs and proposals should have the same length.
        """
        
        storage = get_event_storage()

        # minimum number of boxes to try to visualize per image
        max_vis_prop = 20

        if not hasattr(self, 'thing_classes'):
            self.thing_classes = MetadataCatalog.get('omni3d_model').thing_classes
            self.num_classes = len(self.thing_classes)
        only2d = instances is None
        if only2d:
            instances = [None]*len(batched_inputs)
        for input, prop, instances_i in zip(batched_inputs, proposals, instances):

            img = input["image"]            
            img = convert_image_to_rgb(img.permute(1, 2, 0), self.input_format)
            img_3DGT = np.ascontiguousarray(img.copy()[:, :, [2, 1, 1]]) # BGR
            img_3DPR = np.ascontiguousarray(img.copy()[:, :, [2, 1, 1]]) # BGR

            '''
            Visualize the 2D GT and proposal predictions
            '''
            v_gt = Visualizer(img, None)
            v_gt = v_gt.overlay_instances(boxes=input["instances"].gt_boxes)
            anno_img = v_gt.get_image()
            box_size = min(len(prop.proposal_boxes), max_vis_prop)
            v_pred = Visualizer(img, None)
            v_pred = v_pred.overlay_instances(
                boxes=prop.proposal_boxes[0:box_size].tensor.cpu().numpy()
            )
            prop_img = v_pred.get_image()
            vis_img_rpn = np.concatenate((anno_img, prop_img), axis=1)
            vis_img_rpn = vis_img_rpn.transpose(2, 0, 1)
            storage.put_image("Left: GT 2D bounding boxes; Right: Predicted 2D proposals", vis_img_rpn)
            if only2d:
                break
            '''
            Visualize the 3D GT and predictions
            '''
            K = torch.tensor(input['K'], device=self.device)
            scale = input['height']/img.shape[0]
            fx, sx = (val.item()/scale for val in K[0, [0, 2]])
            fy, sy = (val.item()/scale for val in K[1, [1, 2]])
            
            K_scaled = torch.tensor(
                [[1/scale, 0 , 0], [0, 1/scale, 0], [0, 0, 1.0]], 
                dtype=torch.float32, device=self.device
            ) @ K

            gts_per_image = input["instances"]

            gt_classes = gts_per_image.gt_classes
            
            # Filter out irrelevant groundtruth
            fg_selection_mask = (gt_classes != -1) & (gt_classes < self.num_classes)

            gt_classes = gt_classes[fg_selection_mask]
            gt_class_names = [self.thing_classes[cls_idx] for cls_idx in gt_classes]
            gt_boxes   = gts_per_image.gt_boxes.tensor[fg_selection_mask]  # 2D boxes
            gt_poses   = gts_per_image.gt_poses[fg_selection_mask]         # GT poses

            # projected 2D center, depth, w, h, l, 3D center
            gt_boxes3D = gts_per_image.gt_boxes3D[fg_selection_mask]

            # this box may have been mirrored and scaled so
            # we need to recompute XYZ in 3D by backprojecting.
            gt_z = gt_boxes3D[:, 2]

            gt_x3D = gt_z * (gt_boxes3D[:, 0] - sx)/fx
            gt_y3D = gt_z * (gt_boxes3D[:, 1] - sy)/fy
            
            # put together the GT boxes
            gt_center_3D = torch.stack((gt_x3D, gt_y3D, gt_z)).T
            gt_boxes3D_XYZ_WHL = torch.cat((gt_center_3D, gt_boxes3D[:, 3:6]), dim=1)

            gt_colors = torch.tensor(
                [util.get_color(i) for i in range(len(gt_boxes3D_XYZ_WHL))], 
                device=self.device
            )/255.0

            gt_meshes = util.mesh_cuboid(gt_boxes3D_XYZ_WHL, gt_poses, gt_colors)

            # perform a simple NMS, which is not cls dependent. 
            keep = batched_nms(
                instances_i.pred_boxes.tensor, 
                instances_i.scores, 
                torch.zeros(len(instances_i.scores), dtype=torch.long, device=instances_i.scores.device), 
                self.roi_heads.box_predictor.test_nms_thresh
            )
            
            keep = keep[:max_vis_prop]
            num_to_visualize = len(keep)

            pred_xyzwhl = torch.cat((instances_i.pred_center_cam[keep], instances_i.pred_dimensions[keep]), dim=1)
            pred_pose = instances_i.pred_pose[keep]

            pred_colors = torch.tensor(
                [util.get_color(i) for i in range(num_to_visualize)], 
                device=self.device
            )/255.0

            pred_boxes = instances_i.pred_boxes[keep]
            pred_scores = instances_i.scores[keep]
            pred_classes = instances_i.pred_classes[keep]
            pred_class_names = ['{} {:.2f}'.format(self.thing_classes[cls_idx], score) for cls_idx, score in zip(pred_classes, pred_scores)]
            pred_meshes = util.mesh_cuboid(pred_xyzwhl, pred_pose, pred_colors)

            # convert to lists
            pred_meshes = [pred_meshes.__getitem__(i).detach() for i in range(len(pred_meshes))]
            gt_meshes = [gt_meshes.__getitem__(i) for i in range(len(gt_meshes))]

            img_3DPR = vis.draw_scene_view(img_3DPR, K_scaled.cpu().numpy(), pred_meshes, text=pred_class_names, mode='front', blend_weight=0.0, blend_weight_overlay=0.85)
            img_3DGT = vis.draw_scene_view(img_3DGT, K_scaled.cpu().numpy(), gt_meshes, text=gt_class_names, mode='front', blend_weight=0.0, blend_weight_overlay=0.85)

            # horizontal stack 3D GT and pred left/right
            vis_img_3d = np.concatenate((img_3DGT, img_3DPR), axis=1)
            vis_img_3d = vis_img_3d[:, :, [2, 1, 0]] # RGB
            vis_img_3d = vis_img_3d.astype(np.uint8).transpose(2, 0, 1)

            storage.put_image("Left: GT 3D cuboids; Right: Predicted 3D cuboids", vis_img_3d)

            break  # only visualize one image in a batch

def build_model(cfg, priors=None):
    """
    Build the whole model architecture, defined by ``cfg.MODEL.META_ARCHITECTURE``.
    Note that it does not load any weights from ``cfg``.
    """
    meta_arch = cfg.MODEL.META_ARCHITECTURE
    model = META_ARCH_REGISTRY.get(meta_arch)(cfg, priors=priors)
    model.to(torch.device(cfg.MODEL.DEVICE))
    _log_api_usage("modeling.meta_arch." + meta_arch)
    return model

def build_backbone(cfg, input_shape=None, priors=None):
    """
    Build a backbone from `cfg.MODEL.BACKBONE.NAME`.

    Returns:
        an instance of :class:`Backbone`
    """
    if input_shape is None:
        input_shape = ShapeSpec(channels=len(cfg.MODEL.PIXEL_MEAN))

    backbone_name = cfg.MODEL.BACKBONE.NAME
    backbone = BACKBONE_REGISTRY.get(backbone_name)(cfg, input_shape, priors)
    assert isinstance(backbone, Backbone)
    return backbone