vanilla nerf examples

README.md

@@ -2,15 +2,13 @@
 
 This is a **tiny** tootlbox  for **accelerating** NeRF training & rendering using PyTorch CUDA extensions. Plug-and-play for most of the NeRFs!
 
-## Instant-NGP example
+## Examples: Instant-NGP NeRF
 
+``` bash
+python examples/trainval.py ngp --train_split trainval
 ```
-python examples/trainval.py
-```
-
-## Performance Reference
 
-Ours on TITAN RTX :
+Performance on TITAN RTX :
 
 | trainval | Lego | Mic | Materials | Chair | Hotdog |
 | - | - | - | - | - | - |
@@ -25,6 +23,25 @@ Instant-NGP paper (5 min) on 3090 (w/ mask):
 | PSNR | 36.39 | 36.22 | 29.78 | 35.00 | 37.40 |
 
 
+## Examples: Vanilla MLP NeRF
+
+``` bash
+python examples/trainval.py vanilla --train_split train
+```
+
+Performance on test set:
+
+|  | Lego |
+| - | - |
+| Paper PSNR (train set) | 32.54 |
+| Our PSNR (train set) | 33.21 |
+| Our PSNR (trainval set) | 33.66  |
+| Our train time & test FPS | 45min; 0.43FPS |
+
+For reference, vanilla NeRF paper trains on V100 GPU for 1-2 days per scene. Test time rendering takes about 30 secs to render a 800x800 image. Our model is trained on a TITAN X.
+
+Note: We only use a single MLP with more samples (1024), instead of two MLPs with coarse-to-fine sampling as in the paper. Both ways share the same spirit to do dense sampling around the surface. Our fast rendering inheritly skip samples away from the surface so we can simplly increase the number of samples with a single MLP, to achieve the same goal with coarse-to-fine sampling, without runtime or memory issue.
+
 <!-- 
 
 Tested with the default settings on the Lego test set.

examples/radiance_fields/mlp.py

+""" The MLPs and Voxels. """
+import math
+from typing import Callable, Dict, Optional
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+class MLP(nn.Module):
+    def __init__(
+        self,
+        input_dim: int,  # The number of input tensor channels.
+        output_dim: int = None,  # The number of output tensor channels.
+        net_depth: int = 8,  # The depth of the MLP.
+        net_width: int = 256,  # The width of the MLP.
+        skip_layer: int = 4,  # The layer to add skip layers to.
+        hidden_init: Callable = nn.init.xavier_uniform_,
+        hidden_activation: Callable = nn.ReLU(),
+        output_enabled: bool = True,
+        output_init: Optional[Callable] = nn.init.xavier_uniform_,
+        output_activation: Optional[Callable] = nn.Identity(),
+        bias_enabled: bool = True,
+        bias_init: Callable = nn.init.zeros_,
+    ):
+        super().__init__()
+        self.input_dim = input_dim
+        self.output_dim = output_dim
+        self.net_depth = net_depth
+        self.net_width = net_width
+        self.skip_layer = skip_layer
+        self.hidden_init = hidden_init
+        self.hidden_activation = hidden_activation
+        self.output_enabled = output_enabled
+        self.output_init = output_init
+        self.output_activation = output_activation
+        self.bias_enabled = bias_enabled
+        self.bias_init = bias_init
+
+        self.hidden_layers = nn.ModuleList()
+        in_features = self.input_dim
+        for i in range(self.net_depth):
+            self.hidden_layers.append(
+                nn.Linear(in_features, self.net_width, bias=bias_enabled)
+            )
+            if (self.skip_layer is not None) and (i % self.skip_layer == 0) and (i > 0):
+                in_features = self.net_width + self.input_dim
+            else:
+                in_features = self.net_width
+        if self.output_enabled:
+            self.output_layer = nn.Linear(
+                in_features, self.output_dim, bias=bias_enabled
+            )
+        else:
+            self.output_dim = in_features
+
+        self.initialize()
+
+    def initialize(self):
+        def init_func_hidden(m):
+            if isinstance(m, nn.Linear):
+                if self.hidden_init is not None:
+                    self.hidden_init(m.weight)
+                if self.bias_enabled and self.bias_init is not None:
+                    self.bias_init(m.bias)
+
+        self.hidden_layers.apply(init_func_hidden)
+        if self.output_enabled:
+
+            def init_func_output(m):
+                if isinstance(m, nn.Linear):
+                    if self.output_init is not None:
+                        self.output_init(m.weight)
+                    if self.bias_enabled and self.bias_init is not None:
+                        self.bias_init(m.bias)
+
+            self.output_layer.apply(init_func_output)
+
+    def forward(self, x):
+        inputs = x
+        for i in range(self.net_depth):
+            x = self.hidden_layers[i](x)
+            x = self.hidden_activation(x)
+            if (self.skip_layer is not None) and (i % self.skip_layer == 0) and (i > 0):
+                x = torch.cat([x, inputs], dim=-1)
+        if self.output_enabled:
+            x = self.output_layer(x)
+            x = self.output_activation(x)
+        return x
+
+
+class DenseLayer(MLP):
+    def __init__(self, input_dim, output_dim, **kwargs):
+        super().__init__(
+            input_dim=input_dim,
+            output_dim=output_dim,
+            net_depth=0,  # no hidden layers
+            **kwargs,
+        )
+
+
+class NerfMLP(nn.Module):
+    def __init__(
+        self,
+        input_dim: int,  # The number of input tensor channels.
+        condition_dim: int,  # The number of condition tensor channels.
+        net_depth: int = 8,  # The depth of the MLP.
+        net_width: int = 256,  # The width of the MLP.
+        skip_layer: int = 4,  # The layer to add skip layers to.
+        net_depth_condition: int = 1,  # The depth of the second part of MLP.
+        net_width_condition: int = 128,  # The width of the second part of MLP.
+    ):
+        super().__init__()
+        self.base = MLP(
+            input_dim=input_dim,
+            net_depth=net_depth,
+            net_width=net_width,
+            skip_layer=skip_layer,
+            output_enabled=False,
+        )
+        hidden_features = self.base.output_dim
+        self.sigma_layer = DenseLayer(hidden_features, 1)
+
+        if condition_dim > 0:
+            self.bottleneck_layer = DenseLayer(hidden_features, net_width)
+            self.rgb_layer = MLP(
+                input_dim=net_width + condition_dim,
+                output_dim=3,
+                net_depth=net_depth_condition,
+                net_width=net_width_condition,
+                skip_layer=None,
+            )
+        else:
+            self.rgb_layer = DenseLayer(hidden_features, 3)
+
+    def query_density(self, x):
+        x = self.base(x)
+        raw_sigma = self.sigma_layer(x)
+        return raw_sigma
+
+    def forward(self, x, condition=None):
+        x = self.base(x)
+        raw_sigma = self.sigma_layer(x)
+        if condition is not None:
+            if condition.shape[:-1] != x.shape[:-1]:
+                num_rays, n_dim = condition.shape
+                condition = condition.view(
+                    [num_rays] + [1] * (x.dim() - condition.dim()) + [n_dim]
+                ).expand(list(x.shape[:-1]) + [n_dim])
+            bottleneck = self.bottleneck_layer(x)
+            x = torch.cat([bottleneck, condition], dim=-1)
+        raw_rgb = self.rgb_layer(x)
+        return raw_rgb, raw_sigma
+
+
+class SinusoidalEncoder(nn.Module):
+    """Sinusoidal Positional Encoder used in NeRF."""
+
+    def __init__(self, x_dim, min_deg, max_deg, use_identity: bool = True):
+        super().__init__()
+        self.x_dim = x_dim
+        self.min_deg = min_deg
+        self.max_deg = max_deg
+        self.use_identity = use_identity
+        self.register_buffer(
+            "scales", torch.tensor([2**i for i in range(min_deg, max_deg)])
+        )
+
+    @property
+    def latent_dim(self) -> int:
+        return (int(self.use_identity) + (self.max_deg - self.min_deg) * 2) * self.x_dim
+
+    def forward(self, x: torch.Tensor) -> Dict:
+        """
+        Args:
+            x: [..., x_dim]
+        Returns:
+            latent: [..., latent_dim]
+        """
+        xb = torch.reshape(
+            (x[Ellipsis, None, :] * self.scales[:, None]),
+            list(x.shape[:-1]) + [(self.max_deg - self.min_deg) * self.x_dim],
+        )
+        latent = torch.sin(torch.cat([xb, xb + 0.5 * math.pi], dim=-1))
+        if self.use_identity:
+            latent = torch.cat([x] + [latent], dim=-1)
+        return latent
+
+
+class VanillaNeRFRadianceField(nn.Module):
+    def __init__(
+        self,
+        net_depth: int = 8,  # The depth of the MLP.
+        net_width: int = 256,  # The width of the MLP.
+        skip_layer: int = 4,  # The layer to add skip layers to.
+        net_depth_condition: int = 1,  # The depth of the second part of MLP.
+        net_width_condition: int = 128,  # The width of the second part of MLP.
+    ) -> None:
+        super().__init__()
+        self.posi_encoder = SinusoidalEncoder(3, 0, 10, True)
+        self.view_encoder = SinusoidalEncoder(3, 0, 4, True)
+        self.mlp = NerfMLP(
+            input_dim=self.posi_encoder.latent_dim,
+            condition_dim=self.view_encoder.latent_dim,
+            net_depth=net_depth,
+            net_width=net_width,
+            skip_layer=skip_layer,
+            net_depth_condition=net_depth_condition,
+            net_width_condition=net_width_condition,
+        )
+
+    def query_density(self, x):
+        x = self.posi_encoder(x)
+        sigma = self.mlp.query_density(x)
+        return F.relu(sigma)
+
+    def forward(self, x, condition=None):
+        x = self.posi_encoder(x)
+        if condition is not None:
+            condition = self.view_encoder(condition)
+        rgb, sigma = self.mlp(x, condition=condition)
+        return torch.sigmoid(rgb), F.relu(sigma)

examples/trainval.py

+import argparse
 import math
 import time
 
@@ -6,11 +7,12 @@ import torch
 import torch.nn.functional as F
 import tqdm
 from datasets.nerf_synthetic import SubjectLoader, namedtuple_map
+from radiance_fields.mlp import VanillaNeRFRadianceField
 from radiance_fields.ngp import NGPradianceField
 
 from nerfacc import OccupancyField, volumetric_rendering
 
-TARGET_SAMPLE_BATCH_SIZE = 1 << 18
+TARGET_SAMPLE_BATCH_SIZE = 1 << 16
 
 
 def render_image(radiance_field, rays, render_bkgd, render_step_size):
@@ -78,15 +80,40 @@ def render_image(radiance_field, rays, render_bkgd, render_step_size):
 if __name__ == "__main__":
     torch.manual_seed(42)
 
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "method",
+        type=str,
+        default="ngp",
+        choices=["ngp", "vanilla"],
+        help="which nerf to use",
+    )
+    parser.add_argument(
+        "--train_split",
+        type=str,
+        default="trainval",
+        choices=["train", "trainval"],
+        help="which train split to use",
+    )
+    args = parser.parse_args()
+
     device = "cuda:0"
     scene = "lego"
 
+    # setup the scene bounding box.
+    scene_aabb = torch.tensor([-1.5, -1.5, -1.5, 1.5, 1.5, 1.5])
+    # setup some rendering settings
+    render_n_samples = 1024
+    render_step_size = (
+        (scene_aabb[3:] - scene_aabb[:3]).max() * math.sqrt(3) / render_n_samples
+    ).item()
+
     # setup dataset
     train_dataset = SubjectLoader(
         subject_id=scene,
         root_fp="/home/ruilongli/data/nerf_synthetic/",
-        split="trainval",
-        num_rays=1024,
+        split=args.train_split,
+        num_rays=TARGET_SAMPLE_BATCH_SIZE // render_n_samples,
         # color_bkgd_aug="random",
     )
 
@@ -116,30 +143,28 @@ if __name__ == "__main__":
         batch_size=None,
     )
 
-    # setup the scene bounding box.
-    scene_aabb = torch.tensor([-1.5, -1.5, -1.5, 1.5, 1.5, 1.5])
-
     # setup the scene radiance field. Assume you have a NeRF model and
     # it has following functions:
     # - query_density(): {x} -> {density}
     # - forward(): {x, dirs} -> {rgb, density}
+    if args.method == "ngp":
         radiance_field = NGPradianceField(aabb=scene_aabb).to(device)
+        optimizer = torch.optim.Adam(radiance_field.parameters(), lr=1e-2, eps=1e-15)
+        max_steps = 20000
+        occ_field_warmup_steps = 2000
+        grad_scaler = torch.cuda.amp.GradScaler(1)
+
+    elif args.method == "vanilla":
+        radiance_field = VanillaNeRFRadianceField().to(device)
+        optimizer = torch.optim.Adam(radiance_field.parameters(), lr=5e-4)
+        max_steps = 40000
+        occ_field_warmup_steps = 256
+        grad_scaler = torch.cuda.amp.GradScaler(2**10)
 
-    # setup some rendering settings
-    render_n_samples = 1024
-    render_step_size = (
-        (scene_aabb[3:] - scene_aabb[:3]).max() * math.sqrt(3) / render_n_samples
-    ).item()
-
-    optimizer = torch.optim.Adam(
-        radiance_field.parameters(),
-        lr=1e-2,
-        # betas=(0.9, 0.99),
-        eps=1e-15,
-        # weight_decay=1e-6,
-    )
     scheduler = torch.optim.lr_scheduler.MultiStepLR(
-        optimizer, milestones=[10000, 15000, 18000], gamma=0.33
+        optimizer,
+        milestones=[max_steps // 2, max_steps * 3 // 4, max_steps * 9 // 10],
+        gamma=0.33,
     )
 
     # setup occupancy field with eval function
@@ -167,8 +192,6 @@ if __name__ == "__main__":
     data_time = 0
     tic_data = time.time()
 
-    # Scaling up the gradients for Adam
-    grad_scaler = torch.cuda.amp.GradScaler(2**10)
     for epoch in range(10000000):
         for i in range(len(train_dataset)):
             radiance_field.train()
@@ -183,7 +206,7 @@ if __name__ == "__main__":
             pixels = data["pixels"]
 
             # update occupancy grid
-            occ_field.every_n_step(step)
+            occ_field.every_n_step(step, warmup_steps=occ_field_warmup_steps)
 
             rgb, acc, counter, compact_counter = render_image(
                 radiance_field, rays, render_bkgd, render_step_size
@@ -215,7 +238,7 @@ if __name__ == "__main__":
                 )
 
             # if time.time() - tic > 300:
-            if step >= 20_000 and step % 5000 == 0 and step > 0:
+            if step >= max_steps and step % max_steps == 0 and step > 0:
                 # evaluation
                 radiance_field.eval()
 
@@ -240,23 +263,23 @@ if __name__ == "__main__":
                 #     ((acc > 0).float().cpu().numpy() * 255).astype(np.uint8),
                 # )
 
-                psnrs = []
-                train_dataset.training = False
-                with torch.no_grad():
-                    for data in tqdm.tqdm(train_dataloader):
-                        # generate rays from data and the gt pixel color
-                        rays = namedtuple_map(lambda x: x.to(device), data["rays"])
-                        pixels = data["pixels"].to(device)
-                        render_bkgd = data["color_bkgd"].to(device)
-                        # rendering
-                        rgb, acc, _, _ = render_image(
-                            radiance_field, rays, render_bkgd, render_step_size
-                        )
-                        mse = F.mse_loss(rgb, pixels)
-                        psnr = -10.0 * torch.log(mse) / np.log(10.0)
-                        psnrs.append(psnr.item())
-                psnr_avg = sum(psnrs) / len(psnrs)
-                print(f"evaluation on train: {psnr_avg=}")
+                # psnrs = []
+                # train_dataset.training = False
+                # with torch.no_grad():
+                #     for data in tqdm.tqdm(train_dataloader):
+                #         # generate rays from data and the gt pixel color
+                #         rays = namedtuple_map(lambda x: x.to(device), data["rays"])
+                #         pixels = data["pixels"].to(device)
+                #         render_bkgd = data["color_bkgd"].to(device)
+                #         # rendering
+                #         rgb, acc, _, _ = render_image(
+                #             radiance_field, rays, render_bkgd, render_step_size
+                #         )
+                #         mse = F.mse_loss(rgb, pixels)
+                #         psnr = -10.0 * torch.log(mse) / np.log(10.0)
+                #         psnrs.append(psnr.item())
+                # psnr_avg = sum(psnrs) / len(psnrs)
+                # print(f"evaluation on train: {psnr_avg=}")
                 # imageio.imwrite(
                 #     "acc_binary_train.png",
                 #     ((acc > 0).float().cpu().numpy() * 255).astype(np.uint8),
@@ -267,7 +290,7 @@ if __name__ == "__main__":
                 # )
                 train_dataset.training = True
 
-            if step == 20_000:
+            if step == max_steps:
                 print("training stops")
                 exit()
             tic_data = time.time()