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What are monocular cues? For some people, the term may be “too sciencey.” For people who have been painting and doing some artwork on any medium, this term may already be something that you are familiar with.

But if you are well-versed with it, probably, you won’t be here asking this question! Whatever your reason is, let’s try to make it easy to understand as possible.

The Binocular Cue

The vision we interpret is the post-processed version and rendering of the combined cues taken by our two eyes by the brain. Yes, this may seem too complicated because it is!

What our eyes see individually, the monocular cue is processed by the brain and combine it to give us the correct 3D perspective of depth, size, distance, elevation, and linearity. Without using both eyes to interpret and process our vision, we would be a bit inaccurate in the approximation of all the mentioned qualities.

Can it be more complicated than that? Yes, it can! The refraction and reflection of light relative to our vision is something we should reserve for a textbook, won’t you agree?

But we know you are smart, and you get the point of the binocular cue. In short, the binocular cue is what our two eyes see processed by our brain into one picture.

What are Monocular Cues?

Monocular cue is what a single eye sees and interpret while the other is closed. There are five aspects of monocular cues; linear perspective; relative size; superimposition; texture gradient; and height in plane.

Linear Perspective

This monocular cue tells us how far we are from one point to the other. This helps us approximate the depth of field and gives us an idea that the object or place is far from us. Next time you look at the road, pay attention to the farthest point you can see.

The farther it gets, it’s as if the lines are getting closer to each other. The more cramped up these lines are from your point of reference, the farther it is away from us.

Relative Size

We know you have noticed that things that are far from us look smaller. Right? When in reality, they are the same size when it is just right front of us. Imagine a car that is one block away from you.

It would relatively seem small compared with a car just in front of you. This is how we perceive the monocular cue of relative size.


Superimposition is an element of monocular cue that is closely related to relative size.  An object further away from you can be completely hidden behind an object with the same size. This helps us determine that the other object behind is farther away from us.

Texture Gradient

To deeply understand texture gradient, try looking at a vast open field. Pay close attention to the details of the objects near you. Take a look at a grassy patch.

Have you noticed that the patches of grass near you present more intricate details than the patches of grass away from you? This tells us that the objects with lesser defined details are much further from us.

Next time you go to the countryside, take note of the mountains you see. They are full of trees like the normal trees you see in the park.

However, because they are miles farther away, we don’t see the definition of the leaves, and we only see a green sea of trees.

Height in Plane

This monocular cue tells us the depth and the distance of objects relative to the horizon. The farther objects are from our proximity, the more it seems like they are closer to the horizon.

Look at the cars miles away from you. It seems like they are getting closer to the clouds. This tells us that these objects are far away from us.

Understanding the Cues

These terms are “too sciencey” and are just an explanation of what we practically see. All these might be too much to take in for now, but they all make sense, right?

Here’s a fun thing though. To better appreciate how monocular cues are processed and combined by our brain to give us the right central perspective, try this exercise!

Try covering one eye and check out your surroundings. Now, try it on your other eye. Have you noticed that there’s not much difference? Now, try focusing on one object with one eye closed.

Now close that same eye and open the other. Have you noticed that the object you are focusing at seems like it is shifting from left to right?

Do this a few more times. And while focusing on your object, observe the other stuff behind your main object. Have you noticed how they shift in perspective while you cycle between your eyes?

Lastly, with one eye closed, focus on your object. Now, slowly open your other eye while directly staring at your object. What did you notice? Yep, the object was not really shifting from left to right!

Do this with the other eye. Slowly open your other eye while focused on the subject. Now, how wonderful does the brain work? Magnificent. Right?

The object isn’t really shifting and our brain, with both eyes open, is merely correcting our perception of objects by combining the left and right monocular cue. Isn’t that amazing?

Well, it’s like a complicated process that many wide-angle and 360 cameras are trying to process. The brain does it every time you have your eyes opened without having any trouble at all!

Monocular Cues Made Simple

What are monocular cues? Simply put, monocular cues are the elements that tell us where we are at and how far objects are from us. Monocular cue is the visual interpretation of one eye that the brain can combine with the other to give the correct perspective relative to the central point of origin.

Without these cues, we would be lost as we wouldn’t be able to identify how far or how near things are from us. The good thing is, we have it, and we can determine how close a speeding car is from us!

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