When creating samples from the marked images the default options are listed below. You notice that the default for the maxzangle is less than the defaults for the x and y angle values. So why is that? What do these parameters mean?
C:\OpenCV2.2\bin>opencv_createsamples.exe Usage: opencv_createsamples.exe [-info <collection_file_name>] [-img <image_file_name>] [-vec <vec_file_name>] [-bg <background_file_name>] [-num <number_of_samples = 1000>] [-bgcolor <background_color = 0>] [-inv] [-randinv] [-bgthresh <background_color_threshold = 80>] [-maxidev <max_intensity_deviation = 40>] [-maxxangle <max_x_rotation_angle = 1.100000>] [-maxyangle <max_y_rotation_angle = 1.100000>] [-maxzangle <max_z_rotation_angle = 0.500000>] [-show [<scale = 4.000000>]] [-w <sample_width = 24>] [-h <sample_height = 24>]
The Haar Classifier was initially developed for facial detections, but has been proven to be a good detection method in detecting other objects, as long as you specify the parameters correctly and robustly enough to have a representative set.
[-maxxangle <max_x_rotation_angle = 1.100000>]
So for the x angle value this correlates to rotations along the X axis, which in facial detection refers to looking up and down. So when you run create samples it will create samples based on this rotation specification to take that case into consideration in your training model.
[-maxyangle <max_y_rotation_angle = 1.100000>]
For the y angle value this correlates to rotations along the Y axis, which in facial detection refers to looking left and right. So when you run create samples it will create samples based on this rotation specification to take that case into consideration in your training model.
[-maxzangle <max_z_rotation_angle = 0.500000>]
For the z angle value this correlates to rotations along the Z axis, which is the axis that goes straight into the computer screen (image) and straight toward you. So in facial detection refers to tilting your head from side to side. So when you run create samples it will create samples based on this rotation specification to take that case into consideration in your training model.
If we think of our solar cavity circular form as the circular form of a face this correlates to x representing a cavity more upright and straight in orientation, y representing more of an oblong form transformed inward from the sides and z representing our cavities at an angle. So for solar cavities the majority of them seem to be at an angle as opposed to straight upward in orientation. For facial detection purposes the x and y make more sense as people rarely walk around, take pictures etc. with their heads tilted from side to side, but in relation to this research the z angle value is more important for our detection purposes, so we need to increase this value.
Tags: create samples, Haar Classifier, haar training, opencv, thesis