stella.adapter
Class CenterOfGravityShift

java.lang.Object
  util.PropertyContainer
      util.PropertyResources
          util.PropertyBundles
              stella.adapter.AbstractPinholeShift
                  stella.adapter.CenterOfGravityShift

All Implemented Interfaces:

Cloneable, PinholeShift, Initializable, LocalizedSupplying, PropertySupplying, ResourceSupplying

public class CenterOfGravityShift
extends AbstractPinholeShift

Simple implementation of a pinhole shift detector. From a fixed pinhole position given in the properties, we calculate the shift be appyling a simple center-of-gravity method. The center of gravity is not necessarily the true shift from the pinhole. This can be in a simple way accounted for by the gain factor, splitted for convenience into an x and y gain factor. The recommended way, though, is to feed the shifts derived from this class into a PID control, adjusting the P-term accordingly.

Nested Class Summary

static class

CenterOfGravityShift.Test Test class.

Nested classes/interfaces inherited from class stella.adapter.AbstractPinholeShift

AbstractPinholeShift.Background, AbstractPinholeShift.Evaluate, AbstractPinholeShift.Reconstruct

Nested classes/interfaces inherited from class util.PropertyResources

PropertyResources.URLResource

Field Summary

private static double	DEFXGAIN Default gain factor from fitting artificial images.
private static double	DEFYGAIN Default gain factor from fitting artificial images.
static String	KEY_XGAIN This key is the scaling of the center of gravity shift.
static String	KEY_YGAIN This key is the scaling of the center of gravity shift.

Fields inherited from class stella.adapter.AbstractPinholeShift

KEY_ADNOISE, KEY_APPLICABLE, KEY_GAIN, KEY_PINHOLE, KEY_SIGMACLIP, KEY_SKYTHICK

Fields inherited from class util.PropertyBundles

KEY_LOCALECOUNTRY, KEY_LOCALELANGUAGE, KEY_RESOURCEBUNDLES

Fields inherited from class util.PropertyResources

KEY_NOINITONCREATE, localurl, locate, POSTFIX_DIR, POSTFIX_EXT, POSTFIX_FILE, POSTFIX_LIST, POSTFIX_URL, urlset

Fields inherited from class util.PropertyContainer

KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.ResourceSupplying

KEY_URLRESOURCES, KEY_URLUSECONFIG, KEY_URLUSECURRENT, KEY_URLUSEHOME

Fields inherited from interface util.PropertySupplying

CONFIG, KEY_CLASS

Constructor Summary

CenterOfGravityShift(Map<String,String> prop)
Constructs a new CenterOfGravityShift object.

Method Summary

Vector2D	getBackground(nom.tam.fits.ImageHDU hdu) This method calculates the background as the median of a frame at the outer edge of the apllicable window.
Point2D	initFiberView(nom.tam.fits.Fits ccd) Returns the center of gravity shift of the image from the pinhole position.

Methods inherited from class stella.adapter.AbstractPinholeShift

backgroundFrameMean, backgroundFrameMedian, backgroundMean, backgroundMedian, getAduSignal, getApplicableWindow, getFlux, getFwhm, getPinholePosition, getSignalToNoise, init

Methods inherited from class util.PropertyBundles

clone, getLocalized, getLocalized, getLocalizedString, getLocalizedString, loadResource

Methods inherited from class util.PropertyResources

createFrom, createFrom, createFrom, getApplet, getAsResources, getLocalClassLoader, getPropertiesToKey, getPropertiesToKey, getResource, getResourceAsStream, getResourceFromKey, getResources, keyCreate, keyCreate, reload, setApplet

Methods inherited from class util.PropertyContainer

augment, augment, augment, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, isNew, parseObject, reload, removeProperty, rescanned, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface util.ResourceSupplying

getResource, getResourceAsStream, getResources

Methods inherited from interface util.PropertySupplying

defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, parseObject, removeProperty, setObject, setProperty, stringProperties

Field Detail

KEY_XGAIN

public static final String KEY_XGAIN

This key is the scaling of the center of gravity shift.

See Also:

Constant Field Values

KEY_YGAIN

public static final String KEY_YGAIN

This key is the scaling of the center of gravity shift.

See Also:

Constant Field Values

DEFXGAIN

private static final double DEFXGAIN

Default gain factor from fitting artificial images.

See Also:

Constant Field Values

DEFYGAIN

private static final double DEFYGAIN

Default gain factor from fitting artificial images.

See Also:

Constant Field Values

Constructor Detail

CenterOfGravityShift

public CenterOfGravityShift(Map<String,String> prop)

Constructs a new CenterOfGravityShift object.

Method Detail

getBackground

public Vector2D getBackground(nom.tam.fits.ImageHDU hdu)

This method calculates the background as the median of a frame at the outer edge of the apllicable window.

Returns:

The background ADU in x and its ADU-sigma in y.

initFiberView

public Point2D initFiberView(nom.tam.fits.Fits ccd)

Returns the center of gravity shift of the image from the pinhole position. The true center of gravity is scaled with two functions to return true shifts.

Parameters:

ccd - The image of the pinhole entrance

Returns:

The pixel shift from the pinhole center to the star.