Mark Texture Image

A texture image needs to be marked in order to be used to create texture-mapped surfaces. However, the normal marking methods cannot be used to mark an un-tagged image, since it is impossible to find the exact corresponding feature point on the smooth surface.

The following describes how it can be done using Back-projection:

  1. Mark a few points in the texture image. Find a few feature points and mark them accurately. The marks need to be scattered across the entire image, not just in one small area. Also, make sure that they are merged correctly to the points in the other images. These points will be used to compute the camera parameters of the texture image.
  2. Set the camera parameters of the texture image: Open the Camera Parameters window and set the initial camera parameters the same way you would in another image.
  3. Compute the camera parameters of the texture image: Invoke the Compute 3D dialog. Only select the texture image in the Image List box. Make sure to check the button "Computed P as Ref". This tells Photo4D to use the computed x, y, z value as reference to compute the camera parameters of the texture image. Select other computation parameters as describe in the previous chapter. After proper setup, press "Compute" to compute the camera parameters. After computation, verify the the location and look-at direction of the texture image camera.
  4. Back-project points to the texture image: With computed camera parameters, any point with valid x, y, z values can be projected to the texture image. This can be achieved by using the "Proj" subpage in the Mark page of the Main Window.