viewpoint direction

[bbb]

Hi Jeff,
I thought that myself but in an earlier post i asked you a question regarding the yaw of the euler angles and based on that i understood that i cannot use this so i guess i have some miss understanding, so i will ask again.
I asked you this: if i'm looking on the same thing from different positions in the scene, will i get the same euler angle? your answer was no. So, if i don't get the same euler angle for specific thing in the scene, how can i be able to conclude that from different positions i'm looking at the same thing, based on yaw?

I would appreciate a clarify and thank you for your efforts to solve my issue.