CN103996032A - Face angle determining method based on cranium image coincidence theory - Google Patents

Abstract

The invention discloses a face angle determining method based on a cranium image coincidence theory. The face angle determining method is mainly characterized in that face deflection angles are calculated through two-dimensional facial feature points and include the face horizontal deflection angle and the face pitching deflection angle. By means of the face angle determining method, the face angles are determined through a face deflection index according to the cranium image coincidence theory, and are accurately estimated through the two-dimensional facial feature points; in addition, due to the fact that the face deflection index is used for calculation, limitation of the size of a picture is avoided, and values of the deflection angles can be rapidly found through a convertible regression equation and a convertible curve.

Description

A kind of face angle decision method based on photographic superimposition theory

Technical field

The present invention relates to a kind of face angle decision method based on photographic superimposition theory.

Background technology

The method of both at home and abroad human face posture being estimated at present has three classes substantially: the method based on model, the method based on face outward appearance and the method based on classification.

Method based on model is to utilize geometric model and the unique point of face, between model and image, sets up corresponding relation, then realizes the estimation of human face posture by set or other method.First carry out the detection of unique point, generally adopt eyes, nose and mouth; Then face is set up to three-dimensional model, three-dimensional feature is put to continuous projection and approach the unique point on image; Adopt simple video camera to photograph due to general in reality, be not easy to set up the three-dimensional model of face.

Method based on face outward appearance is that the content of hypothesis human face posture and image exists mutual relation, such as gray scale, gradient etc., then, by a large amount of sample of training, finds out this corresponding relation, thereby carries out the estimation of attitude.Due to a large amount of training sample image of needs, different attitude, illumination all can exert an influence to the confirmation of relation, more complicated.

Method based on classification is to adopt the positive negative sample of training, obtains a statistical value according to sample, and utilizes regression algorithm to calculate regression equation this value, thereby the calculating of attitude is converted to the calculating of regression equation, obtains general angle.Although the method based on classification can find the change direction of human face posture easily, estimate human face posture or some difficulty by this parameter.

Summary of the invention

The object of the present invention is to provide a kind of face angle decision method based on photographic superimposition theory, can utilize two-dimentional face feature point more accurately to estimate face deflection angle.

A face angle decision method based on photographic superimposition theory, comprises the steps:

Step 1, the two-dimentional face feature point of facial image is carried out to coordinate setting, obtain the coordinate figure of left outside eye Le, right outside eye Re, nasion o, glabella point G, subnasal point Nd and gnathion Cd, calculate obtain distance R e-o, the glabella point G of left outside eye Le to the distance L e-o of nasion o, right outside Re to nasion o to the distance G-Nd of subnasal point Nd and subnasal point Nd to gnathion Cd apart from Nd-Cd;

If the left outside eye of step 2 Le equals the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, judge that face X deflection angle is as 0;

If left outside eye Le is not equal to the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, horizontal deflection index X=Le-o/Re-o, by the regression equation Y=91.33-89.09X of face horizontal deflection index X and X deflection angle Y, calculate the value of face X deflection angle Y, when calculate result n>0 time, the n ° that shown deflection left, when result of calculation n<0, the n ° that shown deflection to the right;

?if step 3 glabella point G to the distance G-Nd of subnasal point Nd equal subnasal point Nd to gnathion Cd apart from Nd-Cd, judge that face pitching deflection angle is 0; If glabella point G to the distance G-Nd of subnasal point Nd be not equal to subnasal point Nd to gnathion Cd apart from Nd-Cd, pitching index X=G-Nd/Nd-Cd, by the regression equation Y=94.54-98.70X of pitching index X and luffing angle Y, calculate the value of face pitching deflection angle Y, when calculate result n>0 time, show to have upward deflected n °, when result of calculation n<0, show to have deflected down n °.

Portrait is all consistent (pitching is also identical) with the horizontal deflection index of skull picture on various deflection angles, the present invention carries out the judgement of face angle according to photographic superimposition theory, can utilize two-dimentional face feature point more accurately to estimate face deflection angle, and because using face tilt index, the present invention calculates, be not subject to the restriction of photo size, by can, for the regression equation and the curve that convert, checking in rapidly deflection angle value.

Brief description of the drawings

Fig. 1 is the graph of a relation of the flat tilt index X of inventor's water for washing the face and X deflection angle Y;

Fig. 2 is the graph of a relation of face pitching index X of the present invention and luffing angle Y.

Below in conjunction with the drawings and specific embodiments, the present invention is further described.

Embodiment

A kind of face angle decision method based on photographic superimposition theory of the present invention, is mainly to utilize two-dimentional face feature point to calculate face deflection angle, is divided into face X deflection angle and face pitching deflection angle.

1, calculate and obtain face X deflection angle according to face horizontal deflection index:

In general, face is symmetrical, so left outside eye Le should equate to the distance R e-o of nasion o to distance L e-o and the right outside eye Re of nasion o, for left outside eye Le and right outside eye Re do a connecting line, when face is during just to camera lens, its X deflection angle is 0 degree, at this moment the distance R e-o of left outside eye Le to the distance L e-o of nasion o and right outside Re to nasion o is equal in length, when X deflection angle is not equal to 0 while spending, according to the rule of perspective projection, can be greater than from the length after the side line section imaging close to camera lens that (side away from camera lens is called deflection side from the side away from camera lens, a side close to camera lens is called deflection offside), horizontal deflection index X=Le-o/Re-o so,

As shown in Figure 1, obtain the inverse ratio linear relation of face horizontal deflection index X and X deflection angle Y through statistical test, its regression equation is: Y=91.33-89.09X;

When calculate result n>0 time, the n ° that shown deflection left; When result of calculation n<0, the n ° that shown deflection to the right;

2, calculate and obtain face luffing angle according to face pitching index:

If glabella point G, subnasal point Nd, gnathion Cd, if glabella point G to the distance G-Nd of subnasal point Nd equal subnasal point Nd to gnathion Cd apart from Nd-Cd, judge that face pitching deflection angle is 0, if glabella point G to the distance G-Nd of subnasal point Nd be not equal to subnasal point Nd to gnathion Cd apart from Nd-Cd, pitching index X=G-Nd/Nd-Cd;

When calculate result n>0 time, show to have upward deflected n °; When result of calculation n<0, show to have deflected down n °

As shown in Figure 2, obtain the inverse ratio linear relation of pitching index X and luffing angle Y through statistical test, its regression equation is: Y=94.54-98.70X.

A kind of face angle decision method based on photographic superimposition theory of the present invention, specifically comprises the steps:

Step 1, the two-dimentional face feature point of facial image is carried out to coordinate setting, obtain the coordinate figure of left outside eye Le, right outside eye Re, nasion o, glabella point G, subnasal point Nd and gnathion Cd, calculate obtain distance R e-o, the glabella point G of left outside eye Le to the distance L e-o of nasion o, right outside Re to nasion o to the distance G-Nd of subnasal point Nd and subnasal point Nd to gnathion Cd apart from Nd-Cd;

If the left outside eye of step 2 Le equals the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, judge that face X deflection angle is as 0;

If left outside eye Le is not equal to the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, horizontal deflection index X=Le-o/Re-o, by the regression equation Y=91.33-89.09X of face horizontal deflection index X and X deflection angle Y, calculate the value of face X deflection angle Y; When calculate result n>0 time, the n ° that shown deflection left; When result of calculation n<0, the n ° that shown deflection to the right;

?if step 3 glabella point G to the distance G-Nd of subnasal point Nd equal subnasal point Nd to gnathion Cd apart from Nd-Cd, judge that face pitching deflection angle is 0; If glabella point G to the distance G-Nd of subnasal point Nd be not equal to subnasal point Nd to gnathion Cd apart from Nd-Cd, pitching index X=G-Nd/Nd-Cd, by the regression equation Y=94.54-98.70X of pitching index X and luffing angle Y, calculate the value of face pitching deflection angle Y, when calculate result n>0 time, show to have upward deflected n °; When result of calculation n<0, show to have deflected down n °.

The above, it is only preferred embodiment of the present invention, not technical scope of the present invention is imposed any restrictions, therefore any trickle amendment, equivalent variations and modification that every foundation technical spirit of the present invention is done above embodiment all still belong in the scope of technical solution of the present invention.

Claims (1)

1. the face angle decision method based on photographic superimposition theory, is characterized in that comprising the steps:

Step 1, the two-dimentional face feature point of facial image is carried out to coordinate setting, obtain the coordinate figure of left outside eye Le, right outside eye Re, nasion o, glabella point G, subnasal point Nd and gnathion Cd, calculate obtain distance R e-o, the glabella point G of left outside eye Le to the distance L e-o of nasion o, right outside Re to nasion o to the distance G-Nd of subnasal point Nd and subnasal point Nd to gnathion Cd apart from Nd-Cd;

If the left outside eye of step 2 Le equals the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, judge that face X deflection angle is as 0;

If left outside eye Le is not equal to the distance R e-o of right outside eye Re to nasion o to the distance L e-o of nasion o, horizontal deflection index X=Le-o/Re-o, by the regression equation Y=91.33-89.09X of face horizontal deflection index X and X deflection angle Y, calculate the value of face X deflection angle Y, when calculate result n>0 time, the n ° that shown deflection left, when result of calculation n<0, the n ° that shown deflection to the right;

?if step 3 glabella point G to the distance G-Nd of subnasal point Nd equal subnasal point Nd to gnathion Cd apart from Nd-Cd, judge that face pitching deflection angle is 0; If glabella point G to the distance G-Nd of subnasal point Nd be not equal to subnasal point Nd to gnathion Cd apart from Nd-Cd, pitching index X=G-Nd/Nd-Cd, by the regression equation Y=94.54-98.70X of pitching index X and luffing angle Y, calculate the value of face pitching deflection angle Y, when calculate result n>0 time, show to have upward deflected n °, when result of calculation n<0, show to have deflected down n °.