codecsplat / src /model /decoder /gsplat_splatting.py
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from math import isqrt
from typing import Literal
import torch
from einops import rearrange, repeat
from jaxtyping import Float
from torch import Tensor
from gsplat.rendering import rasterization
GsplatRenderMode = Literal["RGB", "RGB+D", "RGB+ED"]
GsplatRasterizeMode = Literal["classic", "antialiased"]
def normalized_intrinsics_to_pixel_K(
intrinsics: Float[Tensor, "batch view 3 3"],
image_shape: tuple[int, int],
) -> Float[Tensor, "batch view 3 3"]:
h, w = image_shape
K = intrinsics.clone().float()
K[..., 0, 0] *= w
K[..., 1, 1] *= h
K[..., 0, 2] *= w
K[..., 1, 2] *= h
return K
def _identity_quats_like(
means: Float[Tensor, "batch gaussian 3"],
) -> Float[Tensor, "batch gaussian 4"]:
quats = torch.zeros((*means.shape[:-1], 4), device=means.device, dtype=means.dtype)
# gsplat uses wxyz quaternions.
quats[..., 0] = 1.0
return quats
def _xyzw_to_wxyz(
quats: Float[Tensor, "batch gaussian 4"],
) -> Float[Tensor, "batch gaussian 4"]:
return torch.cat((quats[..., 3:4], quats[..., :3]), dim=-1)
@torch.autocast("cuda", enabled=False)
def render_gsplat(
extrinsics: Float[Tensor, "batch view 4 4"],
intrinsics: Float[Tensor, "batch view 3 3"],
near: Float[Tensor, "batch view"],
far: Float[Tensor, "batch view"],
image_shape: tuple[int, int],
background_color: Float[Tensor, "batch 3"],
gaussian_means: Float[Tensor, "batch gaussian 3"],
gaussian_covariances: Float[Tensor, "batch gaussian 3 3"] | None,
gaussian_sh_coefficients: Float[Tensor, "batch gaussian 3 d_sh"],
gaussian_opacities: Float[Tensor, "batch gaussian"],
gaussian_scales: Float[Tensor, "batch gaussian 3"] | None = None,
gaussian_rotations: Float[Tensor, "batch gaussian 4"] | None = None,
render_mode: GsplatRenderMode = "RGB",
use_covariances: bool = True,
eps2d: float = 0.1,
packed: bool = True,
sparse_grad: bool = False,
absgrad: bool = False,
rasterize_mode: GsplatRasterizeMode = "antialiased",
channel_chunk: int = 32,
scale_invariant: bool = False,
) -> tuple[
Float[Tensor, "batch view 3 height width"] | None,
Float[Tensor, "batch view height width"] | None,
Float[Tensor, "batch view height width"],
]:
b, v, _, _ = extrinsics.shape
h, w = image_shape
extrinsics = extrinsics.float()
intrinsics = intrinsics.float()
near = near.float()
far = far.float()
background_color = background_color.float()
gaussian_means = gaussian_means.float()
gaussian_sh_coefficients = gaussian_sh_coefficients.float()
gaussian_opacities = gaussian_opacities.float()
covars = gaussian_covariances.float() if gaussian_covariances is not None else None
scales = gaussian_scales.float() if gaussian_scales is not None else None
# The adapter stores quaternions as xyzw, while gsplat expects wxyz.
quats = (
_xyzw_to_wxyz(gaussian_rotations.float())
if gaussian_rotations is not None
else None
)
if use_covariances:
if covars is None:
raise ValueError("gsplat covariance mode requires gaussians.covariances.")
if scales is None:
scales = torch.ones_like(gaussian_means)
if quats is None:
quats = _identity_quats_like(gaussian_means)
else:
covars = None
if scales is None or quats is None:
raise ValueError(
"gsplat scale/quaternion mode requires gaussians.scales and "
"gaussians.rotations. Prefer use_covariances=true."
)
if scale_invariant:
scale = 1.0 / near[:, :1].clamp_min(1e-8)
extrinsics = extrinsics.clone()
extrinsics[..., :3, 3] = extrinsics[..., :3, 3] * scale[..., None]
gaussian_means = gaussian_means * scale[:, :, None]
near = near * scale
far = far * scale
if covars is not None:
covars = covars * (scale[:, :, None, None] ** 2)
elif scales is not None:
scales = scales * scale[:, :, None]
Ks = normalized_intrinsics_to_pixel_K(intrinsics, image_shape)
viewmats = torch.linalg.inv(extrinsics)
sh_degree = isqrt(gaussian_sh_coefficients.shape[-1]) - 1
shs = rearrange(
gaussian_sh_coefficients, "b g c n -> b g n c"
).contiguous()
render_rgb = "RGB" in render_mode
render_depth = "D" in render_mode
# gsplat's packed path has limited background broadcasting across render
# modes. Our datasets use black backgrounds, so omitting the background keeps
# the memory-efficient packed path available without changing semantics.
backgrounds = (
None
if packed
else repeat(background_color, "b c -> b v c", v=v).to(Ks)
)
render_out, alpha, _ = rasterization(
means=gaussian_means,
quats=quats,
scales=scales,
opacities=gaussian_opacities,
colors=shs,
viewmats=viewmats,
Ks=Ks,
width=w,
height=h,
near_plane=float(near.detach().min().item()),
far_plane=float(far.detach().max().item()),
eps2d=eps2d,
sh_degree=sh_degree,
packed=packed,
backgrounds=backgrounds,
render_mode=render_mode,
sparse_grad=sparse_grad,
absgrad=absgrad,
rasterize_mode=rasterize_mode,
channel_chunk=channel_chunk,
covars=covars,
)
color = (
rearrange(render_out[..., :3], "b v h w c -> b v c h w")
if render_rgb
else None
)
depth = render_out[..., -1] if render_depth else None
return color, depth, alpha.squeeze(-1)
def render_depth_gsplat(
extrinsics: Float[Tensor, "batch view 4 4"],
intrinsics: Float[Tensor, "batch view 3 3"],
near: Float[Tensor, "batch view"],
far: Float[Tensor, "batch view"],
image_shape: tuple[int, int],
background_color: Float[Tensor, "batch 3"],
gaussian_means: Float[Tensor, "batch gaussian 3"],
gaussian_covariances: Float[Tensor, "batch gaussian 3 3"] | None,
gaussian_sh_coefficients: Float[Tensor, "batch gaussian 3 d_sh"],
gaussian_opacities: Float[Tensor, "batch gaussian"],
gaussian_scales: Float[Tensor, "batch gaussian 3"] | None = None,
gaussian_rotations: Float[Tensor, "batch gaussian 4"] | None = None,
mode: Literal["depth", "disparity", "relative_disparity", "log"] = "depth",
use_covariances: bool = True,
eps2d: float = 0.1,
packed: bool = True,
sparse_grad: bool = False,
absgrad: bool = False,
rasterize_mode: GsplatRasterizeMode = "antialiased",
channel_chunk: int = 32,
scale_invariant: bool = False,
) -> Float[Tensor, "batch view height width"]:
render_mode = "RGB+ED" if mode == "relative_disparity" else "RGB+D"
_, depth, _ = render_gsplat(
extrinsics,
intrinsics,
near,
far,
image_shape,
background_color,
gaussian_means,
gaussian_covariances,
gaussian_sh_coefficients,
gaussian_opacities,
gaussian_scales=gaussian_scales,
gaussian_rotations=gaussian_rotations,
render_mode=render_mode,
use_covariances=use_covariances,
eps2d=eps2d,
packed=packed,
sparse_grad=sparse_grad,
absgrad=absgrad,
rasterize_mode=rasterize_mode,
channel_chunk=channel_chunk,
scale_invariant=scale_invariant,
)
assert depth is not None
if mode in ("disparity", "relative_disparity"):
depth = 1.0 / depth.clamp_min(1e-8)
elif mode == "log":
depth = depth.clamp_min(near[..., None, None]).clamp_max(
far[..., None, None]
).log()
return depth