Reduce precision conversion when packing (#124)

* Reduce conversion. Assume that ray_indices should always be long and pack_info always int

* Remove some more casting

* More casting fixes

* Remove unecessary long casting

* Fix changes in precision at python level, ray_pdf_query test is already broken since it was reverted

* Support long when rendering transmittance

* Support long

* Woops

examples/train_ngp_nerf_proposal.py

@@ -58,7 +58,6 @@ def render_image(
         num_rays, _ = rays_shape
 
     def sigma_fn(t_starts, t_ends, ray_indices, net=None):
-        ray_indices = ray_indices.long()
         t_origins = chunk_rays.origins[ray_indices]
         t_dirs = chunk_rays.viewdirs[ray_indices]
         positions = t_origins + t_dirs * (t_starts + t_ends) / 2.0
@@ -68,7 +67,6 @@ def render_image(
             return radiance_field.query_density(positions)
 
     def rgb_sigma_fn(t_starts, t_ends, ray_indices):
-        ray_indices = ray_indices.long()
         t_origins = chunk_rays.origins[ray_indices]
         t_dirs = chunk_rays.viewdirs[ray_indices]
         positions = t_origins + t_dirs * (t_starts + t_ends) / 2.0

examples/utils.py

@@ -48,7 +48,6 @@ def render_image(
         num_rays, _ = rays_shape
 
     def sigma_fn(t_starts, t_ends, ray_indices):
-        ray_indices = ray_indices.long()
         t_origins = chunk_rays.origins[ray_indices]
         t_dirs = chunk_rays.viewdirs[ray_indices]
         positions = t_origins + t_dirs * (t_starts + t_ends) / 2.0
@@ -63,7 +62,6 @@ def render_image(
         return radiance_field.query_density(positions)
 
     def rgb_sigma_fn(t_starts, t_ends, ray_indices):
-        ray_indices = ray_indices.long()
         t_origins = chunk_rays.origins[ray_indices]
         t_dirs = chunk_rays.viewdirs[ray_indices]
         positions = t_origins + t_dirs * (t_starts + t_ends) / 2.0

nerfacc/cuda/csrc/pack.cu

@@ -9,7 +9,7 @@ __global__ void unpack_info_kernel(
     const int n_rays,
     const int *packed_info,
     // output
-    int *ray_indices)
+    long *ray_indices)
 {
     CUDA_GET_THREAD_ID(i, n_rays);
 
@@ -92,12 +92,12 @@ torch::Tensor unpack_info(const torch::Tensor packed_info, const int n_samples)
 
     // int n_samples = packed_info[n_rays - 1].sum(0).item<int>();
     torch::Tensor ray_indices = torch::empty(
-        {n_samples}, packed_info.options().dtype(torch::kInt32));
+        {n_samples}, packed_info.options().dtype(torch::kLong));
 
     unpack_info_kernel<<<blocks, threads, 0, at::cuda::getCurrentCUDAStream()>>>(
         n_rays,
         packed_info.data_ptr<int>(),
-        ray_indices.data_ptr<int>());
+        ray_indices.data_ptr<long>());
     return ray_indices;
 }
 

nerfacc/cuda/csrc/ray_marching.cu

@@ -95,7 +95,7 @@ __global__ void ray_marching_kernel(
     // first round outputs
     int *num_steps,
     // second round outputs
-    int *ray_indices,
+    long *ray_indices,
     float *t_starts,
     float *t_ends)
 {
@@ -259,7 +259,7 @@ std::vector<torch::Tensor> ray_marching(
     int total_steps = cum_steps[cum_steps.size(0) - 1].item<int>();
     torch::Tensor t_starts = torch::empty({total_steps, 1}, rays_o.options());
     torch::Tensor t_ends = torch::empty({total_steps, 1}, rays_o.options());
-    torch::Tensor ray_indices = torch::empty({total_steps}, cum_steps.options());
+    torch::Tensor ray_indices = torch::empty({total_steps}, cum_steps.options().dtype(torch::kLong));
 
     ray_marching_kernel<<<blocks, threads, 0, at::cuda::getCurrentCUDAStream()>>>(
         // rays
@@ -279,7 +279,7 @@ std::vector<torch::Tensor> ray_marching(
         packed_info.data_ptr<int>(),
         // outputs
         nullptr, /* num_steps */
-        ray_indices.data_ptr<int>(),
+        ray_indices.data_ptr<long>(),
         t_starts.data_ptr<float>(),
         t_ends.data_ptr<float>());
 

nerfacc/cuda/csrc/render_transmittance_cub.cu

@@ -20,8 +20,8 @@ template <typename KeysInputIteratorT, typename ValuesInputIteratorT, typename V
 inline void exclusive_sum_by_key(
     KeysInputIteratorT keys, ValuesInputIteratorT input, ValuesOutputIteratorT output, int64_t num_items)
 {
-    TORCH_CHECK(num_items <= std::numeric_limits<int>::max(),
-                "cub ExclusiveSumByKey does not support more than INT_MAX elements");
+    TORCH_CHECK(num_items <= std::numeric_limits<long>::max(),
+                "cub ExclusiveSumByKey does not support more than LONG_MAX elements");
     CUB_WRAPPER(cub::DeviceScan::ExclusiveSumByKey, keys, input, output,
                 num_items, cub::Equality(), at::cuda::getCurrentCUDAStream());
 }
@@ -30,8 +30,8 @@ template <typename KeysInputIteratorT, typename ValuesInputIteratorT, typename V
 inline void exclusive_prod_by_key(
     KeysInputIteratorT keys, ValuesInputIteratorT input, ValuesOutputIteratorT output, int64_t num_items)
 {
-    TORCH_CHECK(num_items <= std::numeric_limits<int>::max(),
-                "cub ExclusiveScanByKey does not support more than INT_MAX elements");
+    TORCH_CHECK(num_items <= std::numeric_limits<long>::max(),
+                "cub ExclusiveScanByKey does not support more than LONG_MAX elements");
     CUB_WRAPPER(cub::DeviceScan::ExclusiveScanByKey, keys, input, output, Product(), 1.0f,
                 num_items, cub::Equality(), at::cuda::getCurrentCUDAStream());
 }
@@ -60,7 +60,7 @@ torch::Tensor transmittance_from_sigma_forward_cub(
     torch::Tensor sigmas_dt_cumsum = torch::empty_like(sigmas);
 #if CUB_SUPPORTS_SCAN_BY_KEY()
     exclusive_sum_by_key(
-        ray_indices.data_ptr<int>(),
+        ray_indices.data_ptr<long>(),
         sigmas_dt.data_ptr<float>(),
         sigmas_dt_cumsum.data_ptr<float>(),
         n_samples);
@@ -97,7 +97,7 @@ torch::Tensor transmittance_from_sigma_backward_cub(
     torch::Tensor sigmas_dt_grad = torch::empty_like(transmittance_grad);
 #if CUB_SUPPORTS_SCAN_BY_KEY()
     exclusive_sum_by_key(
-        thrust::make_reverse_iterator(ray_indices.data_ptr<int>() + n_samples),
+        thrust::make_reverse_iterator(ray_indices.data_ptr<long>() + n_samples),
         thrust::make_reverse_iterator(sigmas_dt_cumsum_grad.data_ptr<float>() + n_samples),
         thrust::make_reverse_iterator(sigmas_dt_grad.data_ptr<float>() + n_samples),
         n_samples);
@@ -123,7 +123,7 @@ torch::Tensor transmittance_from_alpha_forward_cub(
     torch::Tensor transmittance = torch::empty_like(alphas);
 #if CUB_SUPPORTS_SCAN_BY_KEY()
     exclusive_prod_by_key(
-        ray_indices.data_ptr<int>(),
+        ray_indices.data_ptr<long>(),
         (1.0f - alphas).data_ptr<float>(),
         transmittance.data_ptr<float>(),
         n_samples);
@@ -154,7 +154,7 @@ torch::Tensor transmittance_from_alpha_backward_cub(
     torch::Tensor sigmas_dt_grad = torch::empty_like(transmittance_grad);
 #if CUB_SUPPORTS_SCAN_BY_KEY()
     exclusive_sum_by_key(
-        thrust::make_reverse_iterator(ray_indices.data_ptr<int>() + n_samples),
+        thrust::make_reverse_iterator(ray_indices.data_ptr<long>() + n_samples),
         thrust::make_reverse_iterator(sigmas_dt_cumsum_grad.data_ptr<float>() + n_samples),
         thrust::make_reverse_iterator(sigmas_dt_grad.data_ptr<float>() + n_samples),
         n_samples);

nerfacc/grid.py

@@ -300,18 +300,14 @@ def _meshgrid3d(
     """Create 3D grid coordinates."""
     assert len(res) == 3
     res = res.tolist()
-    return (
-        torch.stack(
+    return torch.stack(
         torch.meshgrid(
             [
-                    torch.arange(res[0]),
-                    torch.arange(res[1]),
-                    torch.arange(res[2]),
+                torch.arange(res[0], dtype=torch.long),
+                torch.arange(res[1], dtype=torch.long),
+                torch.arange(res[2], dtype=torch.long),
             ],
             indexing="ij",
         ),
         dim=-1,
-        )
-        .long()
-        .to(device)
-    )
+    ).to(device)

nerfacc/pack.py

@@ -37,8 +37,8 @@ def pack_data(data: Tensor, mask: Tensor) -> Tuple[Tensor, Tensor]:
     ), "mask must be with shape of (n_rays, n_samples)."
     assert mask.dtype == torch.bool, "mask must be a boolean tensor."
     packed_data = data[mask]
-    num_steps = mask.long().sum(dim=-1)
-    cum_steps = num_steps.cumsum(dim=0, dtype=torch.long)
+    num_steps = mask.sum(dim=-1, dtype=torch.int32)
+    cum_steps = num_steps.cumsum(dim=0, dtype=torch.int32)
     packed_info = torch.stack([cum_steps - num_steps, num_steps], dim=-1)
     return packed_data, packed_info
 
@@ -55,26 +55,26 @@ def pack_info(ray_indices: Tensor, n_rays: int = None) -> Tensor:
 
     Returns:
         packed_info: Stores information on which samples belong to the same ray. \
-            See :func:`nerfacc.ray_marching` for details. Tensor with shape (n_rays, 2).
+            See :func:`nerfacc.ray_marching` for details. IntTensor with shape (n_rays, 2).
     """
     assert (
         ray_indices.dim() == 1
     ), "ray_indices must be a 1D tensor with shape (n_samples)."
     if ray_indices.is_cuda:
-        ray_indices = ray_indices.contiguous().int()
+        ray_indices = ray_indices
         device = ray_indices.device
         if n_rays is None:
             n_rays = int(ray_indices.max()) + 1
         # else:
         #     assert n_rays > ray_indices.max()
-        src = torch.ones_like(ray_indices)
+        src = torch.ones_like(ray_indices, dtype=torch.int)
         num_steps = torch.zeros((n_rays,), device=device, dtype=torch.int)
-        num_steps.scatter_add_(0, ray_indices.long(), src)
+        num_steps.scatter_add_(0, ray_indices, src)
         cum_steps = num_steps.cumsum(dim=0, dtype=torch.int)
         packed_info = torch.stack([cum_steps - num_steps, num_steps], dim=-1)
     else:
         raise NotImplementedError("Only support cuda inputs.")
-    return packed_info.int()
+    return packed_info
 
 
 @torch.no_grad()
@@ -86,7 +86,7 @@ def unpack_info(packed_info: Tensor, n_samples: int) -> Tensor:
 
     Args:
         packed_info: Stores information on which samples belong to the same ray. \
-            See :func:`nerfacc.ray_marching` for details. Tensor with shape (n_rays, 2).
+            See :func:`nerfacc.ray_marching` for details. IntTensor with shape (n_rays, 2).
         n_samples: Total number of samples.
 
     Returns:
@@ -115,10 +115,10 @@ def unpack_info(packed_info: Tensor, n_samples: int) -> Tensor:
         packed_info.dim() == 2 and packed_info.shape[-1] == 2
     ), "packed_info must be a 2D tensor with shape (n_rays, 2)."
     if packed_info.is_cuda:
-        ray_indices = _C.unpack_info(packed_info.contiguous().int(), n_samples)
+        ray_indices = _C.unpack_info(packed_info.contiguous(), n_samples)
     else:
         raise NotImplementedError("Only support cuda inputs.")
-    return ray_indices.long()
+    return ray_indices
 
 
 def unpack_data(
@@ -173,7 +173,7 @@ class _UnpackData(torch.autograd.Function):
     @staticmethod
     def forward(ctx, packed_info: Tensor, data: Tensor, n_samples: int):
         # shape of the data should be (all_samples, D)
-        packed_info = packed_info.contiguous().int()
+        packed_info = packed_info.contiguous()
         data = data.contiguous()
         if ctx.needs_input_grad[1]:
             ctx.save_for_backward(packed_info)

nerfacc/ray_marching.py

@@ -193,13 +193,13 @@ def ray_marching(
     if sigma_fn is not None or alpha_fn is not None:
         # Query sigma without gradients
         if sigma_fn is not None:
-            sigmas = sigma_fn(t_starts, t_ends, ray_indices.long())
+            sigmas = sigma_fn(t_starts, t_ends, ray_indices)
             assert (
                 sigmas.shape == t_starts.shape
             ), "sigmas must have shape of (N, 1)! Got {}".format(sigmas.shape)
             alphas = 1.0 - torch.exp(-sigmas * (t_ends - t_starts))
         elif alpha_fn is not None:
-            alphas = alpha_fn(t_starts, t_ends, ray_indices.long())
+            alphas = alpha_fn(t_starts, t_ends, ray_indices)
             assert (
                 alphas.shape == t_starts.shape
             ), "alphas must have shape of (N, 1)! Got {}".format(alphas.shape)

nerfacc/sampling.py

@@ -127,7 +127,7 @@ def proposal_sampling_with_filter(
     for proposal_fn, n_samples in zip(proposal_sigma_fns, proposal_n_samples):
 
         # compute weights for resampling
-        sigmas = proposal_fn(t_starts, t_ends, ray_indices.long())
+        sigmas = proposal_fn(t_starts, t_ends, ray_indices)
         assert (
             sigmas.shape == t_starts.shape
         ), "sigmas must have shape of (N, 1)! Got {}".format(sigmas.shape)
@@ -152,7 +152,7 @@ def proposal_sampling_with_filter(
         # Rerun the proposal function **with** gradients on filtered samples.
         if proposal_require_grads:
             with torch.enable_grad():
-                sigmas = proposal_fn(t_starts, t_ends, ray_indices.long())
+                sigmas = proposal_fn(t_starts, t_ends, ray_indices)
                 weights = render_weight_from_density(
                     t_starts, t_ends, sigmas, ray_indices=ray_indices
                 )
@@ -168,7 +168,7 @@ def proposal_sampling_with_filter(
 
     # last round filtering with sigma_fn
     if (alpha_thre > 0 or early_stop_eps > 0) and (sigma_fn is not None):
-        sigmas = sigma_fn(t_starts, t_ends, ray_indices.long())
+        sigmas = sigma_fn(t_starts, t_ends, ray_indices)
         assert (
             sigmas.shape == t_starts.shape
         ), "sigmas must have shape of (N, 1)! Got {}".format(sigmas.shape)

nerfacc/vol_rendering.py

@@ -78,7 +78,7 @@ def rendering(
 
     # Query sigma/alpha and color with gradients
     if rgb_sigma_fn is not None:
-        rgbs, sigmas = rgb_sigma_fn(t_starts, t_ends, ray_indices.long())
+        rgbs, sigmas = rgb_sigma_fn(t_starts, t_ends, ray_indices)
         assert rgbs.shape[-1] == 3, "rgbs must have 3 channels, got {}".format(
             rgbs.shape
         )
@@ -94,7 +94,7 @@ def rendering(
             n_rays=n_rays,
         )
     elif rgb_alpha_fn is not None:
-        rgbs, alphas = rgb_alpha_fn(t_starts, t_ends, ray_indices.long())
+        rgbs, alphas = rgb_alpha_fn(t_starts, t_ends, ray_indices)
         assert rgbs.shape[-1] == 3, "rgbs must have 3 channels, got {}".format(
             rgbs.shape
         )
@@ -143,7 +143,7 @@ def accumulate_along_rays(
     Args:
         weights: Volumetric rendering weights for those samples. Tensor with shape \
             (n_samples,).
-        ray_indices: Ray index of each sample. IntTensor with shape (n_samples).
+        ray_indices: Ray index of each sample. LongTensor with shape (n_samples).
         values: The values to be accmulated. Tensor with shape (n_samples, D). If \
             None, the accumulated values are just weights. Default is None.
         n_rays: Total number of rays. This will decide the shape of the ouputs. If \
@@ -190,9 +190,10 @@ def accumulate_along_rays(
         n_rays = int(ray_indices.max()) + 1
     # assert n_rays > ray_indices.max()
 
-    ray_indices = ray_indices.int()
-    index = ray_indices[:, None].long().expand(-1, src.shape[-1])
-    outputs = torch.zeros((n_rays, src.shape[-1]), device=weights.device)
+    index = ray_indices[:, None].expand(-1, src.shape[-1])
+    outputs = torch.zeros(
+        (n_rays, src.shape[-1]), device=src.device, dtype=src.dtype
+    )
     outputs.scatter_add_(0, index, src)
     return outputs
 
@@ -524,7 +525,7 @@ class _RenderingTransmittanceFromDensityCUB(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, ray_indices, t_starts, t_ends, sigmas):
-        ray_indices = ray_indices.contiguous().int()
+        ray_indices = ray_indices.contiguous()
         t_starts = t_starts.contiguous()
         t_ends = t_ends.contiguous()
         sigmas = sigmas.contiguous()
@@ -550,7 +551,7 @@ class _RenderingTransmittanceFromDensityNaive(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, packed_info, t_starts, t_ends, sigmas):
-        packed_info = packed_info.contiguous().int()
+        packed_info = packed_info.contiguous()
         t_starts = t_starts.contiguous()
         t_ends = t_ends.contiguous()
         sigmas = sigmas.contiguous()
@@ -576,7 +577,7 @@ class _RenderingTransmittanceFromAlphaCUB(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, ray_indices, alphas):
-        ray_indices = ray_indices.contiguous().int()
+        ray_indices = ray_indices.contiguous()
         alphas = alphas.contiguous()
         transmittance = _C.transmittance_from_alpha_forward_cub(
             ray_indices, alphas
@@ -600,7 +601,7 @@ class _RenderingTransmittanceFromAlphaNaive(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, packed_info, alphas):
-        packed_info = packed_info.contiguous().int()
+        packed_info = packed_info.contiguous()
         alphas = alphas.contiguous()
         transmittance = _C.transmittance_from_alpha_forward_naive(
             packed_info, alphas
@@ -624,7 +625,7 @@ class _RenderingWeightFromDensityNaive(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, packed_info, t_starts, t_ends, sigmas):
-        packed_info = packed_info.contiguous().int()
+        packed_info = packed_info.contiguous()
         t_starts = t_starts.contiguous()
         t_ends = t_ends.contiguous()
         sigmas = sigmas.contiguous()
@@ -652,7 +653,7 @@ class _RenderingWeightFromAlphaNaive(torch.autograd.Function):
 
     @staticmethod
     def forward(ctx, packed_info, alphas):
-        packed_info = packed_info.contiguous().int()
+        packed_info = packed_info.contiguous()
         alphas = alphas.contiguous()
         weights = _C.weight_from_alpha_forward_naive(packed_info, alphas)
         if ctx.needs_input_grad[1]:

scripts/run_profiler.py

@@ -97,7 +97,7 @@ def main():
     cpu_t, cuda_t, cuda_bytes = profiler(fn)
     print(f"{cpu_t:.2f} us, {cuda_t:.2f} us, {cuda_bytes / 1024 / 1024:.2f} MB")
 
-    packed_info = nerfacc.pack_info(ray_indices, n_rays=batch_size).int()
+    packed_info = nerfacc.pack_info(ray_indices, n_rays=batch_size)
     fn = (
         lambda: nerfacc.vol_rendering._RenderingDensity.apply(
             packed_info, t_starts, t_ends, sigmas, 0

tests/test_ray_marching.py

@@ -39,7 +39,7 @@ def test_marching_with_grid():
         far_plane=1.0,
         render_step_size=1e-2,
     )
-    ray_indices = ray_indices.long()
+    ray_indices = ray_indices
     samples = (
         rays_o[ray_indices] + rays_d[ray_indices] * (t_starts + t_ends) / 2.0
     )

tests/test_rendering.py

@@ -18,7 +18,7 @@ eps = 1e-6
 @pytest.mark.skipif(not torch.cuda.is_available, reason="No CUDA device")
 def test_render_visibility():
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (samples,)
     alphas = torch.tensor(
         [0.4, 0.3, 0.8, 0.8, 0.5], dtype=torch.float32, device=device
@@ -48,7 +48,7 @@ def test_render_visibility():
 @pytest.mark.skipif(not torch.cuda.is_available, reason="No CUDA device")
 def test_render_weight_from_alpha():
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (samples,)
     alphas = torch.tensor(
         [0.4, 0.3, 0.8, 0.8, 0.5], dtype=torch.float32, device=device
@@ -71,7 +71,7 @@ def test_render_weight_from_alpha():
 @pytest.mark.skipif(not torch.cuda.is_available, reason="No CUDA device")
 def test_render_weight_from_density():
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (samples,)
     sigmas = torch.rand(
         (ray_indices.shape[0], 1), device=device
@@ -92,7 +92,7 @@ def test_render_weight_from_density():
 @pytest.mark.skipif(not torch.cuda.is_available, reason="No CUDA device")
 def test_accumulate_along_rays():
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (n_rays,)
     weights = torch.tensor(
         [0.4, 0.3, 0.8, 0.8, 0.5], dtype=torch.float32, device=device
@@ -116,7 +116,7 @@ def test_rendering():
         return torch.hstack([t_starts] * 3), t_starts
 
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (samples,)
     sigmas = torch.rand(
         (ray_indices.shape[0], 1), device=device
@@ -136,7 +136,7 @@ def test_rendering():
 @pytest.mark.skipif(not torch.cuda.is_available, reason="No CUDA device")
 def test_grads():
     ray_indices = torch.tensor(
-        [0, 2, 2, 2, 2], dtype=torch.int32, device=device
+        [0, 2, 2, 2, 2], dtype=torch.int64, device=device
     )  # (samples,)
     packed_info = torch.tensor(
         [[0, 1], [1, 0], [1, 4]], dtype=torch.int32, device=device