The Point Cloud is used to generate the 3D Textured Mesh, which is a surface composed by triangles. During the process of the 3D Textured Mesh generation, the vertices of the triangles are defined so as to minimize the distance between some points of the Point Cloud and the surface. Therefore given the resolution that you chose for generating the 3D Texture Mesh some features may be excluded.
To increase the resolution of your mesh you have two options:
- either you change the minimum number of matches to 2 that will densify the Point Cloud therefore the mesh will be improved as well (please note that this setting might cause noise to the point cloud)
- or you can choose the high resolution options for your mesh which is by default set as medium (this will slow the step two depending on the resources of your machine)
Using a Processing Area for the cross may bring improvements in your results but consider that the new 3D Point Cloud and 3D Mesh will be generated only for the new area and will overwrite your previous one. Therefore if you want to keep your previous results, copy them in another folder before you generate the new one.
For more information on processing options please see the articles: https://support.pix4d.com/hc/en-us/articles/208194103 and https://support.pix4d.com/hc/en-us/articles/202557799