EYES + EYEBROWS | Upper Hot Spots - Jan 2017

 Upper Face "HOT SPOTS"
Maximize Emotional Impact 

KEY CONCEPT:  We focus much more on the eyes and inner eyebrow than anywhere else on the face, except the mouth.

Figure 1.

Brains are efficient – they pay particular attention to the parts of our environment that will give us the most information for the least work.  When it comes to assessing the degree of illumination on a surface divided into shadow and light, for example, we focus on the boundary where there is the most rapid change from one to the other.  Tonal changes that occur elsewhere on the surface don’t register nearly as strongly, allowing artists to use the shadow edge to either intensify, or diminish, the amount of perceived contrast and brightness. 

Similarly, when we want to know what mood someone is in, we ignore the details of almost all of the face in favor of two small regions: the area around the mouth, and the area that includes the eye white, iris, and inner eyebrows (Figure 1).  These two “hot spots” are responsible for the key changes that allow us to quickly identify the cardinal expressions of anger, sadness, joy, surprise, fear, and disgust.   Movements elsewhere in the face, while they may seem expressive (like the full cheeks of a smile, or radically raised brows), carry much less weight in our perception. ​

​Figure 2.
​Neutral face.

Figure 3. 
​Highlighted "hot spots."

Figure 4. Clown makeup accents facial "hot spots"

Above, I’ve drawn a neutral face (Figure 2) and then used a red tone to map out the "hot spots" responsible​ for more than 90% of the expressive information (Figure 3) of the face.  You will note the limited area represented by the shaded zones, and how these two regions correspond – very roughly – to the parts of the face addressed by makeup: makeup for women makes the expressive parts of the face appear larger, more dramatic, and more noticeable; makeup for clowns  transforms the same parts of the face, with the addition of the bulb nose, blown up for comic value. 

​I talk about the lower "hot spot" (the mouth) in a later blog; here I focus on the eyes and brows.  It’s not as though there is no change in the aspect of a face when an eyebrow moves in the area above this hot zone, or tips upwards with its outer end.  But the amount and type of change we perceive with these actions is slight and ambiguous, compared to the much more powerful effects of movements inside the "hot spot."

Figure 5. 

Figure 6. 

Figure 7. 

I’ve included several examples.  In the three pictures above, I’ve moved the eyebrows into the part of the forehead that is outside the "hot spot."  In Figure 5, the outer corners of the eyebrows raise up (note that the "hot spot" only includes the inner third or so of the brows), and the effect on the resulting face is slight and ambiguous.  In Figure 6 and Figure 7, although the raised brows make the face look slightly sleepy (we sometimes do this action in an attempt to keep our tired eyelids from drooping), there is only a small effect compared to the amount the eyebrows have moved.  Adding wrinkles, although a realistic feature, changes nothing in the expression. 

Figure 8.

On the other hand, the very slight inner twist in the brows of Fig. 8 gives us a much stronger emotional jolt.  The message of sadness or distress is quite clear. ​

Figure 9.

Similarly, the frown in Fig. 9 is unmistakable, although frowns by their nature are a bit harder to ascribe to one cause without participation by the mouth.   Some observers might describe this face as thoughtful or perplexed others as stern or annoyed.  But there is a very expressive change from the neutral face in comparison to the ambiguous expressions of Fig. 5, 6, and 7.

Figure 10.

Figure 11.

​Even more bang for the artist’s buck is created by tiny alterations in the arc of the upper eyelid, perhaps the hottest spot of the “hot spot.”  Note the increasing intensity in Figure 11, compared to Figure 10, and how much more penetrating the eye looks than the neutral eye of Figure 2.  

Figure 12.

Figure 13.

​Figures 12 and 13, on the other hand, are disturbingly sleepy or intoxicated- looking, with Fig. 13 more advanced in this direction.  

These stronger interpretations are achieved with tiny differences in the position of the line of the upper eyelid, and the corresponding amount of dark iris that is exposed, or occluded. We are primed and ready to respond to such alterations, made inside the “hot spot,” 

Figure 14. The arc of the eyelids and occluded irises give the giant crab ​her highly expressive appeal.

​The faces I drew here are realistic; however, the principle of “hot spots” applies equally to stylized characters, although the exact boundaries of the “hot spot” depend on the particular character design.  With Tamatoa (Figure14), the giant crab in “Moana,” for example, there are no eyebrows, so the "hot spot" is focused on the shape of the eyelids and the amount of iris that is exposed.

For animators, there is one extremely important consequence of the “hot spot” principle.  When technicians attempt to use motion capture to record the expressive movements of an actor’s face, there needs to be extremely dense and detailed coverage of the area corresponding to the ocular “hot spot" described above. Most of the point arrays I’ve seen for motion capture around the eyes and brow include only a tiny number of capture points in this area, which yields far too coarse and generalized a data set to successfully replicate the intense subtlety required.  For the time being, cg artists are still required to take the crude results of motion capture and modify by hand the feature details in the “hot spots” that will make the desired expressions of their characters work most effectively.  

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Credits: Top: Animated character, Simba, from "The Lion King," produced by  Walt Disney Feature Animation, and released by Walt Disney Pictures, 1994; All  b+ w illustrations (Figures 1 to 13 except 4)  by Gary Faigin,;  Figure 4: photo of "sad clown face painting" from http://www.myartifaces.com/face-painting/; Figure 14 Giant crab "Tamatoa" from Moana, voiced by Jemaine Clement, produced by Walt Disney Animation Studios and resleased by Walt Disney Pictures, 2016.