IO

splax.io reads and writes 3DGS .ply files in render space. The two functions are exact inverses of each other.

Loading

splax.io.load_ply reads a 3DGS .ply and maps the stored activation-space fields to the render-space arrays that render consumes:

scales  = exp(scale_i)
quats   = normalize(rot_i)
colors  = clip(f_dc_i * C0 + 0.5, 0, 1)
opac    = sigmoid(opacity)

It returns (means, scales, quats, colors, opacities) as float32 JAX arrays with shapes (N, 3), (N, 3), (N, 4), (N, 3), (N, 1).

means, scales, quats, colors, opacities = splax.io.load_ply("scene.ply")

Writing

splax.io.write_ply takes the render-space arrays, the same tensors render consumes, and writes the inverse activation-space fields.

splax.io.write_ply("out.ply", means, scales, quats, colors, opacities)

Opacities may be passed as (N, 1) or (N,).

Round-trip and SH degree 0

splax renders spherical harmonics of degree 0 only, a single per-gaussian color. On write, normals are zeroed and the higher-order SH field f_rest is omitted because load_ply reads neither. A file written by write_ply therefore round-trips exactly back through load_ply.