emcGetGridAlignments

NAME

emcGetGridAlignments - Retrieve current specimen grid alignment

SYNOPSIS

#include "emc.h"
int emcGetGridAlignments(EM *em, int units, double *x0, double *y0,
                         double *theta, double delta);

DESCRIPTION

emcGetGridAlignments() retrieves the current orientation of the specimen grid. Simply returns the values last set by emcSetGridAlignments(). Typically there will be an application which guides the EM operator through the specimen loading process. One of the tasks in this process is identifying the grid origin (x0,y0), angle of rotation (theta), distance between grid squares (delta). The procedure generally involves identifying the origin grid square and the logical (1,1) grid square.

*em

points to an EM control and communications structure that was returned by the emcOpen() call.

units

the units the retrieved values should be expressed in:

UNCALIBRATED_UNITS	Native goniometer positioning units
ANGSTOM_UNITS	Units are measured in angstroms
NANOMETER_UNITS	Units are measured in nanometers
MICRON_UNITS	Units are measured in microns
PIXEL_UNITS	Units are measured in pixels in current camera

*x0

X-axis position of logical origin of specimen grid

*y0

Y-axis position of logical origin of specimen grid

*theta

Angle of rotation (in radians)

*delta

Distance to adjacent grid square

RESTRICTIONS

Specimen grid is assumed to organized as regularly spaced squares. Does not take into account irregularities in the shape of the gird. This is unrealistic, perhaps a more accurate method will be implemented in the future.

DIAGNOSTICS

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