tracel-ai/burn · error

Asymmetric padding is not yet supported for conv3d

Error message

Asymmetric padding is not yet supported for conv3d

What it means

Feature-limit guard in the high-level `conv3d`: the ConvOptions padding may be asymmetric per-side, but conv3d only supports symmetric padding (same value before/after each spatial dim); if `options.is_asymmetric()` the call panics. The failing input is ConvOptions with unequal padding per side on any of the 3 spatial dims.

Source

Thrown at crates/burn-tensor/src/tensor/module.rs:161

/// Asymmetric 3D padding is not yet supported.
/// The deprecated [`PaddedConvOptions`](crate::ops::PaddedConvOptions) is also
/// accepted for compatibility.
pub fn conv3d(
    x: Tensor<5>,
    weight: Tensor<5>,
    bias: Option<Tensor<1>>,
    options: impl Into<ConvOptions<3>>,
) -> Tensor<5> {
    let options = options.into();
    check!(TensorCheck::conv(
        "conv3d",
        x.dims(),
        weight.dims(),
        options.groups,
    ));

    if options.is_asymmetric() {
        panic!("Asymmetric padding is not yet supported for conv3d");
    }

    Tensor::new(BridgeTensor::float(Dispatch::conv3d(
        x.primitive.into_float(),
        weight.primitive.into_float(),
        bias.map(|b| b.primitive.into_float()),
        options,
    )))
}

/// Applies a [Deformable 2D convolution](burn_backend::ops::ModuleOps::deform_conv2d).
pub fn deform_conv2d(
    x: Tensor<4>,
    offset: Tensor<4>,
    weight: Tensor<4>,
    mask: Option<Tensor<4>>,
    bias: Option<Tensor<1>>,
    options: DeformConvOptions<2>,

View on GitHub (pinned to d16f7ba2ed)

Solutions

1. Use symmetric padding: set padding so the before/after amounts are equal for each dim.
2. Manually pad the input tensor (e.g. `x.pad(...)`) to emulate asymmetric padding and pass zero padding to conv3d.
3. Crop the input or adjust kernel/stride so symmetric padding suffices.

When it happens

Trigger: Thrown at crates/burn-tensor/src/tensor/module.rs:161 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of tracel-ai/burn@d16f7ba2ed (2026-09-05). Data as JSON: /api/errors/b92918d789cdad87. Report an issue: GitHub.