Merge pull request #2 from duckietown/RPi_homography_fix_attempt

Everything related to detection goodness removed

README.md

@@ -46,7 +46,7 @@ If you also want to extract the tag pose, `estimate_tag_pose` should be set to `
 | tag_id          	| The decoded ID of the tag.                                                                                                                                                                                                                                                                                                                                                                                 	|
 | hamming         	| How many error bits were corrected? Note: accepting large numbers of corrected errors leads to greatly increased false positive rates. NOTE: As of this implementation, the detector cannot detect tags with a Hamming distance greater than 2.                                                                                                                                                            	|
 | decision_margin 	| A measure of the quality of the binary decoding process: the average difference between the intensity of a data bit versus the decision threshold. Higher numbers roughly indicate better decodes. This is a reasonable measure of detection accuracy only for very small tags-- not effective for larger tags (where we could have sampled anywhere within a bit cell and still gotten a good detection.) 	|
-| homography      	| The 3x3 homography matrix describing the projection from an "ideal" tag (with corners at (-1,1), (1,1), (1,-1), and (-1, -1)) to pixels in the image. CURRENTLY NOT IMPLEMENTED DUE TO A NULL POINTER ERROR ON RPI                                                                                                                                                                                          	|
+| homography      	| The 3x3 homography matrix describing the projection from an "ideal" tag (with corners at (-1,1), (1,1), (1,-1), and (-1, -1)) to pixels in the image.                                                                                                             	|
 | center          	| The center of the detection in image pixel coordinates.                                                                                                                                                                                                                                                                                                                                                    	|
 | corners         	| The corners of the tag in image pixel coordinates. These always wrap counter-clock wise around the tag.                                                                                                                                                                                                                                                                                                    	|
 | pose_R*         	| Rotation matrix of the pose estimate.                                                                                                                                                                                                                                                                                                                                                                      	|

apriltags3.py

@@ -69,7 +69,6 @@ class _ApriltagDetection(ctypes.Structure):
         ('family', ctypes.POINTER(_ApriltagFamily)),
         ('id', ctypes.c_int),
         ('hamming', ctypes.c_int),
-        ('goodness', ctypes.c_float),
         ('decision_margin', ctypes.c_float),
         ('H', ctypes.POINTER(_Matd)),
         ('c', ctypes.c_double*2),
@@ -146,7 +145,6 @@ def __init__(self):
         self.tag_family = None
         self.tag_id = None
         self.hamming = None
-        self.goodness = None
         self.decision_margin = None
         self.homography = None
         self.center = None
@@ -160,7 +158,6 @@ def __str__(self):
         '\ntag_family = ' + str(self.tag_family)+
         '\ntag_id = ' + str(self.tag_id)+
         '\nhamming = ' + str(self.hamming)+
-        '\ngoodness = ' + str(self.goodness)+
         '\ndecision_margin = ' + str(self.decision_margin)+
         '\nhomography = ' + str(self.homography)+
         '\ncenter = ' + str(self.center)+
@@ -355,15 +352,14 @@ def detect(self, img, estimate_tag_pose=False, camera_params=None, tag_size=None
 
             tag = apriltag.contents
 
-            homography = numpy.zeros((3,3)) #_matd_get_array(tag.H).copy() # Don't ask questions, move on with your life
+            homography = _matd_get_array(tag.H).copy() # numpy.zeros((3,3))  # Don't ask questions, move on with your life
             center = numpy.ctypeslib.as_array(tag.c, shape=(2,)).copy()
             corners = numpy.ctypeslib.as_array(tag.p, shape=(4, 2)).copy()
 
             detection = Detection()
             detection.tag_family = ctypes.string_at(tag.family.contents.name)
             detection.tag_id = tag.id
             detection.hamming = tag.hamming
-            detection.goodness = tag.goodness
             detection.decision_margin = tag.decision_margin
             detection.homography = homography
             detection.center = center