Hair simulation method
Methods and systems are provided for generating/simulating hair on a 3D model taking into consideration some information from an image of a person, such as for example, the stage of hair loss, to determine which methodology or algorithm to use to generate the hair. The methods and systems of the present application are especially useful in those applications where it is desirable to display the existing hair together with newly simulated hair.
1. A method of simulating hair on a 3D model of a head, the method comprising:
assigning a stage of hair loss to a 3D model of a head comprising hair; and
simulating one or more additional hair on the 3D model based on the assigned stage of hair loss,
wherein, if the assigned stage of hair loss is below a threshold value, the one or more additional hair is simulated using a first approach of hair representation, and if the assigned stage of hair loss is at or above the threshold value, the one or more additional hair is simulated using a second approach of hair representation.
2. The method of claim 1 , wherein the first approach comprises simulating a projected hair and the second approach comprises simulating a volumetric hair.
3. The method of claim 2 , wherein simulating a projected hair comprises generating a volumetric hair and projecting and blending said volumetric hair with the 3D model.
4. The method of claim 1 , further comprising matching the simulated one or more additional hair with a natural hair color of the 3D model.
5. The method of claim 4 , wherein color matching comprises selecting an area with the hair on the 3D model and extracting at least two major colors from the selected area.
6. The method of claim 1 , wherein assigning comprises receiving input from a user through a user interface or automatically assigning using an image processor.
7. A method of simulating hair on a 3D model, the method comprising:
using one or more images of a person's head comprising existing hair to create a 3D model of the person's head;
determining from the one or more images or from the simulated 3D model a corresponding stage of hair loss; and
simulating one or more additional hair on the 3D model based on the determined stage of hair loss, wherein the additional hair is depicted by a first representation if the stage of hair loss is below a threshold value, and the additional hair is depicted by a second representation if the stage of hair loss is at or above the threshold value.
8. The method of claim 7 , wherein one or more images comprises at least two images.
9. The method of claim 7 , wherein determination of the corresponding stage of hair loss comprises manually selecting from two or more stages of hair loss available.
10. The method of claim 7 , wherein the stage of hair loss is based on existence of a receding hair line, a bald spot and its size, or both, and/or whether a receding hair line and a bald spot meet.
11. The method of claim 7 , wherein the stage of hair loss is determined using the Norwood scale of hair loss or Ludwig scale of hair loss.
12. The method of claim 11 , wherein the threshold value is Norwood scale 5 .
13. The method of claim 11 , wherein the first representation comprises a projection of a volumetric simulated hair on the 3D model, and the second representation comprises simulating hair using a volumetric approach.
14. The method of claim 13 , wherein projecting the volumetric simulated hair comprises projecting it such that an angle between a body surface and a first segment of the hair is less than a predetermined angle.
15. The method of claim 14 , wherein the predetermined angle is preferably twenty degrees or less.
16. The method of claim 7 , wherein the one of the first or the second representation comprises volumetric hair simulation.
17. The method of claim 7 , wherein simulating one or more additional hair comprises simulating a hair in the form of a plurality of hair segments, each segment placed end to end and at an angle to an adjacent segment.
18. The method of claim 17 , wherein the angles between some of all of the adjacent segments are variable and a greater angle between the adjacent segments represents a greater curl of the simulated additional hair, and a lesser angle between the adjacent segments represents a straighter additional simulated hair.
19. The method of claim 17 , wherein the number of hair segments is fixed and/or a length of each hair segment is fixed.
20. The method of claim 17 , wherein the number of hair segments can be varied to achieve a predetermined length of the additional simulated hair.
21. The method of claim 17 , wherein a length of each of the plurality of segments is combined to form a length of one additional hair.
22. The method of claim 7 , further comprising blending the additional simulated hairs with the existing hair on the 3D model, wherein blending comprises manipulation of longitudinal edges of the additional hair such that the edges are less distinct.
23. The method of claim 22 , further comprising adjusting a level of blending by means of a sliding scale mechanism.
24. The method of claim 7 , further comprising adjusting a density of the additional hair.
25. The method of claim 7 , wherein determination of the stage of hair loss comprises extracting information from the images based on a percentage of hair relative to a percentage of scalp.
26. The method of claim 7 , wherein the 3D model is created by combining a plurality of morphed 3-D models.
27. The method of claim 26 , wherein each of the plurality of morphed 3-D models comprises a 3-D model which was morphed by mapping predefined features from one or more 2-D image.
28. A system for simulating hair on a 3D model of a head, the system comprising:
a user interface including a user input device;
at least one non-transitory storage medium storing instructions, and
one or more modules for executing operations on image data, the one or more modules comprising instructions for:
assigning a stage of hair loss to a 3D model; and
simulating one or more additional hairs on the 3D model based on the assigned stage of hair loss,
wherein, if the assigned stage of hair loss is below a threshold value, the one or more additional hair is simulated using a first approach of hair representation, and if the assigned stage of hair loss is at or above the threshold value, the one or more additional hair is simulated using a second approach of hair representation.
29. The system of claim 28 , wherein the one or more modules further comprises instructions for executing a color match, blending or both.