Fourier Shell Correlation (FSC) is the most commonly used method for resolution determination of a 3D structure reconstruction.
This logic applies the “gold standard” FSC calculation for resolution determination of a 3D structure reconstruction where the data had been split into two randomly chosen halves earlier. After independent reconstruction of both halves, the FSC fall-off at different resolution levels can be used to determine the reconstruction quality. Additionally, a mask can be supplied to limit the 3D volume to be calculated with.
Parameters and I/O
| Parameters | Description |
| Calculate resolution | Picks the resolution mode to be used |
| → Plot threshold curves | Enabling results in all possible threshold curves being included in the output |
| Mask | Enables use of an input mask |
| → invert mask | Invert the selected/not selected volume of the mask |
| → Mask Threshold | Threshold for counting mask voxel for mean calculation |
| Asymmetric units (3 sigma) | Number of asymmetric units in the 3D |
| Pixel size | Used pixel size in the 3Ds (Pixel/Angstrom) |
| Input | Description |
| First3D | First 3D Structure/Reconstructed 3D from first half of data |
| Mask | Optional input, can be used to restrict 3D volume to only look at certain parts of the reconstruction |
| Second3D | Second 3D Structure/Reconstructed 3D from second half of data |
| FourierShellCorrelation | A Graph showing the calculated FSC (y-axis, ranging from 0 to 1) against resolution (x-axis, Angstrom) |
| Output | Description |
| FourierShellCorrelation | A Graph showing the calculated FSC (y-axis, ranging from 0 to 1) against resolution (x-axis, Angstrom) |
| Written Header Values | Description |
| resolutionAt0.143 | Estimated resolution for FSC cut off at 0.143 |
| resolutionAt0.3 | Estimated resolution for FSC cut off at 0.3 |
| resolutionAt0.5 | Estimated resolution for FSC cut off at 0.5 |
| resolutionAt0.9 | Estimated resolution for FSC cut off at 0.9 |
| resolutionAt3Sigma | Estimated resolution for FSC cut off at 3 Sigma |
| resolution | Estimated resolution at the user chosen cut off value |
| maxResolution | Maximum resolution in the local map |
| meanResolution | Mean resolution in the local map |
| minResolution | Minimum resolution in the local map |
| resolutionVariance | Variance of the resolution in the local map |
| abscissaIsLogarithmical , abscissaMin, abscissaMax | For internal 1D viewer use only, to be hidden |
A Paper about FSC theory and applications can be found here