Can Humans actually see 3D Objects? More generic, Can an n-dimensional being ever see an n-dimensional object?. It is my understanding that both of our eyes are capturing projections, and without both of them, we will lose our sense of depth perception. But is sensing depth enough to claim we can see 3D? If humans were 2D beings, then how could we see anything other than straight lines or line-segments? And if we were 4D beings, wouldn't it be only then we can sense 3D?
Image Credit: A two-point perspective illustration created by User:Matticus78 in CorelDRAW 
Source: https://en.wikipedia.org/wiki/File:Phantogram_projection_diagram.svg

[EDIT]: Before posting this question in PSE, I read about image construction in the retina(s) of a human, so I need to clarify something. By using the word actually, I want to transcend our understanding of seeing beyond reconstruction of a 3D model and have a discussion about how beings in other dimensions are capable of seeing things and how that sense is quantitatively less/more than our (beings in 3D space) capabilities, thus creating a direct relation between the dimension we live in and the way we measure objects by looking at it. Thanks for all your replies. 
 A: Yes a 3 dimensional being could see in 3 dimensions.
Here is a theoretical example: a being equiped with a bubble chamber (see: bubble chamber) reacting to some wavelength spectrum could get a correct 3D image of a defined spectrum (in term of wavelength) and of a defined region of space. This bubble chamber should be filled with photosensitive cells distributed in 3D in large but finite number and small enough to have the smallest possible shadow. This theoretical would only produce a discrete image and would require a brain to construct an illusion of a continuous image (as human brain does it pretty well: we have a good illusion of continuous environnment).
The natural selection didn't yet reach the bubble chamber complexity of construct. This is the reason why bubble chambers aren't in wide use among different actual forms of life on Earth .
A: Our brain builds a 3D model based on 2 dimensional cues, including binocular disparity, shading, relative motion, texture changes, etc. The brain usually succeeds in building the most likely 3D structure based on the available information, however it can be tricked by many visual illusions. Any 2D projection is compatible with an infinite number of possible 3d scenes, however most of these are discarded by our brain as unlikely.
A: Can we see any object? What happens is that our lenses produce 2D images on the retina. Nature invented optics long before we did. These images are converted into rgb signals in the cones. These signals are used by the visual cortex to construct a 3D image using pattern recognition. The 3D image exists only between our ears. The 2D images can be argued to physically exist on our retina, but even a 2D image, as we finally see it, is reconstructed by our brains.
