CurvedImage2D.h

Class CurvedImage2D can be used to make a crosscut through an image with a dimensionality >= 2. The dimensionality of the resulting image is one less. The crosscut is based on a curve defined by a PixelCurve1D object. The curve can be any 1-dim function (e.g. straight line, spline) supported by the Functionals module. The curve must be in one of the main planes of the image as defined by the axes arguments in the constructor.
For example: in an RA-DEC-FREQ image a straight line can be defined in the RA-DEC plane (axis1=0, axis2=1) from blc {0,0) to trc (511,511). The crosscut will follow this line, so the result is a 2-dim image with axes 'line' and FREQ. So it contains the spectrum for all points on the line (points (0,0), (1,1) ... (511,511)).
In this example the line only contains exact grid points. In practice that usually won't be case, so interpolation has to be done. This is done by a class derived from CLInterpolator2D, so any interpolation scheme is possible. Currently only the nearest neighbour scheme is implemented (CLIPNearest2D).

Example

The following example uses a 3-dim image. It makes a crosscut using a line from the blc to the trc in the XY plane. The number of points on the line is the maximum of the number of points in X and Y.

    // Open an image.
    PagedImage<Float> image("name.img");
    // Make a straight line from (0,0) to the trc.
    IPosition shp = lat.shape();
    Int xtop = shp(0);
    Int ytop = shp(1);
    Int nr = xtop;
    if (nr > ytop) nr = ytop;
    PixelCurve1D pc(0, 0, xtop-1, ytop-1, nr);
    // Create the crosscut image.
    // The new axis (the curve axis) is the first axis in the result.
    CurvedImage2D<Float> clat(image, CLIPNearest2D<Float>(), pc, 0, 1, 0);

Note that in the general case the line (or any curve) won't be from the blc to the trc. In fact, it is possible to give any starting and end point and any number of points on the curve.

Motivation

Users like to view arbitrary image crosscuts.

Member Description

CurvedImage2D()

The default constructor

CurvedImage2D (const ImageInterface<T>&, const CLInterpolator2D<T>&, const PixelCurve1D&, uInt axis1, uInt axis2, Int curveAxis=-1)

Take a curved slice from the given image. The PixelCurve1D object defines the curve in one of the planes of the image. The arguments axis1 and axis2 define the plane the curve is in. The CLInterpolator2D object defines the interpolation scheme for pixels that are not on grid points. An example is CLIPNearest2D which takes the nearest neighbour. The dimensionality of the CurvedImage2D is one less than the dimensionality of the given image. Two axes (axis1 and axis2) are replaced by the new axis representing the curve. The argument curveAxis defines the axis number of the new axis. It defaults to the last axis. An exception is thrown if the dimensionality of the input image is < 2 or if the given axes numbers are too high. Note that the output CoordinateSystem of the CurvedImage is just a dummy LinearCoordinate at this point. The values are all arbitrary.

CurvedImage2D (const CurvedImage2D<T>& other)

Copy constructor (reference semantics).

virtual ~CurvedImage2D()

CurvedImage2D<T>& operator= (const CurvedImage2D<T>& other)

Assignment (reference semantics).

virtual ImageInterface<T>* cloneII() const

Make a copy of the object (reference semantics).

virtual String imageType() const

Get the image type (returns name of derived class).

virtual Bool isMasked() const

Is the CurvedImage2D masked? It is if its parent image is masked.

virtual Bool hasPixelMask() const

Does the image object have a pixelmask? It does if its parent has a pixelmask.

virtual const Lattice<Bool>& pixelMask() const
virtual Lattice<Bool>& pixelMask()

Get access to the pixelmask in use (thus to the pixelmask of the parent). An exception is thrown if the parent does not have a pixelmask.

virtual const LatticeRegion* getRegionPtr() const

Get the region used (always returns 0).

virtual Bool isPersistent() const

A CurvedImage2D is not persistent.

virtual Bool isPaged() const

Is the CurvedImage2D paged to disk?

virtual Bool isWritable() const

An CurvedImage2D is not writable

virtual IPosition shape() const

Returns the shape of the CurvedImage2D

virtual uInt advisedMaxPixels() const

This function returns the recommended maximum number of pixels to include in the cursor of an iterator.

virtual void resize(const TiledShape& newShape)

Function which changes the shape of the CurvedImage2D. Throws an exception as resizing an CurvedImage2D is not possible.

virtual String name (Bool stripPath=False) const

Return the name of the parent ImageInterface object.

virtual Bool ok() const

Check class invariants.

virtual Bool doGetSlice (Array<T>& buffer, const Slicer& section)

Do the actual getting of an array of values.

virtual void doPutSlice (const Array<T>& sourceBuffer, const IPosition& where, const IPosition& stride)

Putting data is not possible.

virtual Bool doGetMaskSlice (Array<Bool>& buffer, const Slicer& section)

Get a section of the mask.

virtual LatticeIterInterface<T>* makeIter (const T& navigator, Bool useRef) const

This function is used by the LatticeIterator class to generate an iterator of the correct type for this Lattice. Not recommended for general use.

virtual IPosition doNiceCursorShape (uInt maxPixels) const

Get the best cursor shape.

virtual Bool lock (FileLocker::LockType, uInt nattempts)
virtual void unlock()
virtual Bool hasLock (FileLocker::LockType) const
virtual void resync()
virtual void flush()
virtual void tempClose()
virtual void reopen()

Handle the (un)locking and syncing, etc..