Esempio n. 1
0
def get_image_to_chip_transform(bbox, chipsz, theta):
    """
    transforms image space into chipspace

    Args:
        bbox   - bounding box of chip in image space
        chipsz - size of the chip
        theta  - rotation of the bounding box

    Sympy:
        # https://groups.google.com/forum/#!topic/sympy/k1HnZK_bNNA
        from vtool.patch import *  # NOQA
        import sympy
        import sympy.abc
        theta = sympy.abc.theta

        x, y, w, h, target_area  = sympy.symbols('x y w h, a')
        gx, gy  = sympy.symbols('gx, gy')

        round = sympy.floor  # hack

        ht = sympy.sqrt(target_area * h / w)
        wt = w * ht / h
        cw_, ch_ = round(wt), round(ht)

        from vtool import ltool
        T1 = ltool.translation_mat3x3(tx1, ty1, dtype=None)
        S  = ltool.scale_mat3x3(sx, sy, dtype=None)
        R  = ltool.rotation_mat3x3(-theta, sympy.sin, sympy.cos)
        T2 = ltool.translation_mat3x3(tx2, ty2, dtype=None)

        def add_matmul_hold_prop(mat):
            #import functools
            mat = sympy.Matrix(mat)
            def matmul_hold(other, hold=False):
                new = sympy.MatMul(mat, other, hold=hold)
                add_matmul_hold_prop(new)
                return new
            setattr(mat, 'matmul_hold', matmul_hold)
            return mat

        T1 = add_matmul_hold_prop(T1)
        T2 = add_matmul_hold_prop(T2)
        R = add_matmul_hold_prop(R)
        S = add_matmul_hold_prop(S)

        C = T2.multiply(R.multiply(S.multiply(T1)))
        sympy.simplify(C)

    """
    (x, y, w, h) = bbox
    (cw_, ch_) = chipsz
    tx1 = -(x + (w / 2.0))
    ty1 = -(y + (h / 2.0))
    sx = (cw_ / w)
    sy = (ch_ / h)
    tx2 = (cw_ / 2.0)
    ty2 = (ch_ / 2.0)
    # Translate from bbox center to (0, 0)
    T1 = ltool.translation_mat3x3(tx1, ty1)
    # Scale to chip height
    S  = ltool.scale_mat3x3(sx, sy)
    # Rotate to chip orientation
    R  = ltool.rotation_mat3x3(-theta)
    # Translate from (0, 0) to chip center
    T2 = ltool.translation_mat3x3(tx2, ty2)
    # Merge into single transformation (operate left-to-right aka data on left)
    C = T2.dot(R.dot(S.dot(T1)))
    return C
Esempio n. 2
0
def get_image_to_chip_transform(bbox, chipsz, theta):
    """
    transforms image space into chipspace

    Args:
        bbox   - bounding box of chip in image space
        chipsz - size of the chip
        theta  - rotation of the bounding box

    Sympy:
        # https://groups.google.com/forum/#!topic/sympy/k1HnZK_bNNA
        from vtool.patch import *  # NOQA
        import sympy
        import sympy.abc
        theta = sympy.abc.theta

        x, y, w, h, target_area  = sympy.symbols('x y w h, a')
        gx, gy  = sympy.symbols('gx, gy')

        round = sympy.floor  # hack

        ht = sympy.sqrt(target_area * h / w)
        wt = w * ht / h
        cw_, ch_ = round(wt), round(ht)

        from vtool import ltool
        T1 = ltool.translation_mat3x3(tx1, ty1, dtype=None)
        S  = ltool.scale_mat3x3(sx, sy, dtype=None)
        R  = ltool.rotation_mat3x3(-theta, sympy.sin, sympy.cos)
        T2 = ltool.translation_mat3x3(tx2, ty2, dtype=None)

        def add_matmul_hold_prop(mat):
            #import functools
            mat = sympy.Matrix(mat)
            def matmul_hold(other, hold=False):
                new = sympy.MatMul(mat, other, hold=hold)
                add_matmul_hold_prop(new)
                return new
            setattr(mat, 'matmul_hold', matmul_hold)
            return mat

        T1 = add_matmul_hold_prop(T1)
        T2 = add_matmul_hold_prop(T2)
        R = add_matmul_hold_prop(R)
        S = add_matmul_hold_prop(S)

        C = T2.multiply(R.multiply(S.multiply(T1)))
        sympy.simplify(C)

    """
    (x, y, w, h) = bbox
    (cw_, ch_) = chipsz
    tx1 = -(x + (w / 2.0))
    ty1 = -(y + (h / 2.0))
    sx = (cw_ / w)
    sy = (ch_ / h)
    tx2 = (cw_ / 2.0)
    ty2 = (ch_ / 2.0)
    # Translate from bbox center to (0, 0)
    T1 = ltool.translation_mat3x3(tx1, ty1)
    # Scale to chip height
    S = ltool.scale_mat3x3(sx, sy)
    # Rotate to chip orientation
    R = ltool.rotation_mat3x3(-theta)
    # Translate from (0, 0) to chip center
    T2 = ltool.translation_mat3x3(tx2, ty2)
    # Merge into single transformation (operate left-to-right aka data on left)
    C = T2.dot(R.dot(S.dot(T1)))
    return C