1) Download and install xNormal from http://www.xnormal.net/Downloads.aspx

2) Prepare mesh in .obj ​format (in PhotoScan this can be done with model exporting)

3) Launch xNormal

4) On the right choose section High ​​definition ​​meshes​, and than with Right Click -> Add ​​meshes​ choose .obj ​​file:

Add high mesh

5) On the right choose section Low​ ​definition ​​meshes​, and than with Right Click -> Add ​​meshes​ choose the same .obj​:

Add low mesh

6) In the right part of the same section ​enable Match ​​UVs​ checkbox:

Enable uv keeping

7) Configure backing options (like Output ​​file ​​and Size​) and press Generate​​ Maps​:

Backing options

8) Waiting for result make take some time (proportionally to result texture size and number of polygons in mesh):

Waiting for result

9) When map generated - close the window:

Close the results window

10) Check resulting Ambient Occlusion map (in Output ​​file​​ configured in step ​​7​):

Result AO texture

11) More interesting to look at this AO texture on the model:

AO textured mesh