Spectral Angle Mapper

Module Interface

class torchmetrics.SpectralAngleMapper(reduction='elementwise_mean', **kwargs)

The Spectral Angle Mapper determines the spectral similarity between image spectra and reference spectra by calculating the angle between the spectra, where small angles between indicate high similarity and high angles indicate low similarity.

Parameters

• reduction (Literal[‘elementwise_mean’, ‘sum’, ‘none’]) –

  a method to reduce metric score over labels.

  • 'elementwise_mean': takes the mean (default)

  • 'sum': takes the sum

  • 'none' or None: no reduction will be applied

• kwargs (Any) – Additional keyword arguments, see Advanced metric settings for more info.

Returns

Tensor with SpectralAngleMapper score

Example

>>> import torch
>>> from torchmetrics import SpectralAngleMapper
>>> preds = torch.rand([16, 3, 16, 16], generator=torch.manual_seed(42))
>>> target = torch.rand([16, 3, 16, 16], generator=torch.manual_seed(123))
>>> sam = SpectralAngleMapper()
>>> sam(preds, target)
tensor(0.5943)

References

[1] Roberta H. Yuhas, Alexander F. H. Goetz and Joe W. Boardman, “Discrimination among semi-arid landscape endmembers using the Spectral Angle Mapper (SAM) algorithm” in PL, Summaries of the Third Annual JPL Airborne Geoscience Workshop, vol. 1, June 1, 1992.

Initializes internal Module state, shared by both nn.Module and ScriptModule.

compute()

Computes spectra over state.

Return type

Tensor

update(preds, target)

Update state with predictions and targets.

Parameters

• preds (Tensor) – Predictions from model

• target (Tensor) – Ground truth values

Return type

None

Functional Interface

torchmetrics.functional.spectral_angle_mapper(preds, target, reduction='elementwise_mean')

Universal Spectral Angle Mapper.

Parameters

• preds (Tensor) – estimated image

• target (Tensor) – ground truth image

• reduction (Literal[‘elementwise_mean’, ‘sum’, ‘none’, None]) –

  a method to reduce metric score over labels.

  • 'elementwise_mean': takes the mean (default)

  • 'sum': takes the sum

  • 'none' or None: no reduction will be applied

Return type

Tensor

Returns

Tensor with Spectral Angle Mapper score

Raises

• TypeError – If preds and target don’t have the same data type.

• ValueError – If preds and target don’t have BxCxHxW shape.

Example

>>> from torchmetrics.functional import spectral_angle_mapper
>>> preds = torch.rand([16, 3, 16, 16], generator=torch.manual_seed(42))
>>> target = torch.rand([16, 3, 16, 16], generator=torch.manual_seed(123))
>>> spectral_angle_mapper(preds, target)
tensor(0.5943)

References

[1] Roberta H. Yuhas, Alexander F. H. Goetz and Joe W. Boardman, “Discrimination among semi-arid landscape endmembers using the Spectral Angle Mapper (SAM) algorithm” in PL, Summaries of the Third Annual JPL Airborne Geoscience Workshop, vol. 1, June 1, 1992.