From 194506397eb30cc79edc94a15085d35d312233f1 Mon Sep 17 00:00:00 2001
From: Alexander Mordvintsev <no@email>
Date: Tue, 14 Jun 2011 15:02:57 +0000
Subject: [PATCH] python helper routines (common.py) added

---
 samples/python2/calibrate.py |  3 +-
 samples/python2/common.py    | 72 ++++++++++++++++++++++++++++++++++++
 samples/python2/video.py     |  1 +
 3 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 samples/python2/common.py

diff --git a/samples/python2/calibrate.py b/samples/python2/calibrate.py
index f334ba261a..cc35535450 100644
--- a/samples/python2/calibrate.py
+++ b/samples/python2/calibrate.py
@@ -26,8 +26,7 @@ if __name__ == '__main__':
     try: img_mask = img_mask[0]
     except: img_mask = '../cpp/left*.jpg'
     img_names = glob(img_mask)
-    try: debug_dir = args['--debug']
-    except: debug_dir = None
+    debug_dir = args.get('--debug')
 
     pattern_size = (9, 6)
     pattern_points = np.zeros( (np.prod(pattern_size), 3), np.float32 )
diff --git a/samples/python2/common.py b/samples/python2/common.py
new file mode 100644
index 0000000000..27e1b340e7
--- /dev/null
+++ b/samples/python2/common.py
@@ -0,0 +1,72 @@
+import numpy as np
+import cv2
+
+def to_list(a):
+    return [tuple(p) for p in a]
+
+def anorm2(a):
+    return (a*a).sum(-1)
+def anorm(a):
+    return np.sqrt( anorm2(a) )
+
+def homotrans(H, x, y):
+    xs = H[0, 0]*x + H[0, 1]*y + H[0, 2]
+    ys = H[1, 0]*x + H[1, 1]*y + H[1, 2]
+    s  = H[2, 0]*x + H[2, 1]*y + H[2, 2]
+    return xs/s, ys/s
+
+def to_rect(a):
+    a = np.ravel(a)
+    if len(a) == 2:
+        a = (0, 0, a[0], a[1])
+    return np.array(a, np.float64).reshape(2, 2)
+
+def rect2rect_mtx(src, dst):
+    src, dst = to_rect(src), to_rect(dst)
+    cx, cy = (dst[1] - dst[0]) / (src[1] - src[0])
+    tx, ty = dst[0] - src[0] * (cx, cy)
+    M = np.float64([[ cx,  0, tx],
+                    [  0, cy, ty],
+                    [  0,  0,  1]])
+    return M
+
+
+def lookat(eye, target, up = (0, 0, 1)):
+    fwd = np.asarray(target, np.float64) - eye
+    fwd /= anorm(fwd)
+    right = np.cross(fwd, up)
+    right /= anorm(right)
+    down = np.cross(fwd, right)
+    Rt = np.zeros((3, 4))
+    Rt[:,:3] = [right, down, fwd]
+    Rt[:,3] = -np.dot(Rt[:,:3], eye)
+    return Rt
+
+def mtx2rvec(R):
+    pass
+    
+
+if __name__ == '__main__':
+    import cv2
+    from time import clock
+
+    '''
+    w, h = 640, 480
+    while True:
+        img = np.zeros((h, w, 3), np.uint8)
+        t = clock()
+        eye = [5*cos(t), 5*sin(t), 3]
+        Rt = lookat(eye, [0, 0, 0])
+    '''
+
+
+
+    eye = [1, -4, 3]
+    target = [0, 0, 0]
+    Rt = lookat(eye, [0, 0, 0])
+    print Rt
+    p = [0, 0, 0]
+    print cv2.transform(np.float64([[p]]), Rt)
+
+    print cv2.SVDecomp(Rt[:,:3])
+
diff --git a/samples/python2/video.py b/samples/python2/video.py
index 232f3aee74..a87d9771f9 100644
--- a/samples/python2/video.py
+++ b/samples/python2/video.py
@@ -64,6 +64,7 @@ def create_capture(source):
 
 
 presets = dict(
+    empty = 'synth:',
     lena = 'synth:bg=../cpp/lena.jpg:noise=0.1'
 )