Method for determining the angular magnitude of imaging acquiring apparatus and vehicle collision warning system using thereof

A vehicle collision system, comprising:

• an image acquiring apparatus for acquiring an image surrounded a vehicle;
• an image processing and controlling unit for calculating a position of a feature of the image with respect to the calibrating tool according to an image coordinate system and a characteristic value of the feature of the calibrating tool associated with a spatial coordinate system, performing an iterative angle-calculating procedure according to the position and the characteristic value for obtaining an installed angle of the image acquiring apparatus, and analyzing a relative distance calculated according to the image, the installed angle and installed height of the image acquiring apparatus, between the vehicle and objectives around the vehicle so as to determine if it is necessary to generate an alarm signal;
• a display unit, electrically coupled to the image processing and controlling unit, for displaying the image;
• and
• an alarm unit, electrically coupled to the image processing and controlling unit, for receiving the alarm signal to generate an alarm message.