def get_sample_depth(sample,depth_data):
	""" Depth in meters of the sample.
		From the formula given here : 
		http://support.echoview.com/WebHelp/Reference/Algorithms/Calculating_sample_range_and_depth_from_exported_data.htm
	"""
	return depth_data['depth_start'] + depth_data['depth_per_pixel'] * (sample + 0.5)