FINAL #2: Six Monocular Depth Cues

FINAL #2: Six Monocular Depth Cues

This is a final exercise from the Immersive Education course that I am taking at Boston College. The course is called Discovering Computer Graphics.

For details, visit the immersive BC portal at http://ImmersiveEducation.org/@/bc

1. Size Differences

An example of how size differences make an image appear 3D on a 2D canvas (such as a computer screen or sketchpad) is the trees in the red circled area above. The trees, although along the same plane, give the appearance of depth by growing increasingly smaller the further away (or you may say growing larger the closer to).

2. Occlusion

Another monocular depth cue to simulate 3 dimensions on a flat canvas is occlusion, which tells the viewer about the relative position of objects/elements in front of them. The red circled area shows multiple examples of occlusion - for one, the porch rail blocks out some of the image of the house to show that it is in front of it thus closer to the viewer. Another example is the slant of the roof appearing as if it sticks out further than the wall. Through the window we can see blocked off objects, and our mind reads that as being inside.

3. Lighting and Shading

The rocket above shows how the differences in brightness of color to darkness of color make flat images appear to have depth and shape. This technique immediately calls to mind a hobby of mine, sketching and painting. The yellow lines above represent where the light comes from (in this image, where the sun is) - the parts that are directly hit by the rays (yellow lines) is the brightest, progressing as a gradient to darkest furtherest from the light (each black circle shows an example of this on both the triangle part and cylinder part of the rocket).

4. Texture Density

The technique of texture density is related to size differences. In the red circle marked 1. notice the length and width of the waves. Notice how in the red circle marked 2. the waves are shorter and thinner, continuing with circle 3. and eventually loosing all detail in 4.

5. Linear Perspective

This both makes me think of perspective drawing as well and is related to size differences. The horizon line is where the water/ground "touch" the sky. In the middle of it (though it can be anywhere along the horizon line) is a point where all the red lines converge. This is the vanishing point. It gives perspective. Each red line shows linear perspective by getting proportionally smaller and convening to the farthest spot from the viewer.

6. Atmospheric Perspective

Atmospheric perspective is the effect of objects/elements that are farther away appearing blurrier, bluer. Basically, the more room between the eye and an object the more room for atmospheric conditions to alter the light rays whose reflection makes up all that the brain sees. (Also has to do with the shortness of blue rays of light.) The red circle shows this technique at work in the virtual reality setting. Notice the difference in color and detail of the first hill (the one the robot is standing on) and the next hump (it is blurrier, grayer). Next, look "beyond" the second hump and you realize that the ocean is all foggy and blurry.