map_info
Determine MRC/CCP4 map voxel size and geometry from the header alone, deriving values correctly to avoid common pitfalls and flag anisotropic or cropped maps.
Instructions
Report an MRC/CCP4 map's geometry, above all its voxel size.
Reads only the 1024-byte header — the map data is never loaded, PyMOL is never touched, and nothing goes over the network.
Voxel size is not stored in the header, it is derived, and the derivation has a trap: it is cella/m (the grid sampling), not cella/n (the stored extent). Those differ on any boxed or cropped map, and dividing by n gives a wrong answer of the right order of magnitude. The nominal value is only expected to be accurate to ±5–15% in the first place, which at 1.2 Å is a systematic stretch of every distance in the model. Anisotropy, cropping and axis permutation are all flagged loudly.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | Path to an MRC/CCP4 map file (.mrc/.map/.ccp4, optionally gzipped) |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |