Hi friends!
A luminous body radiates light in all directions and in a straight line. When these straight lines of light touch an opaque (non-transparent) object, it reflects the light and prevents it from passing through, which produces shades in the parts that are not touched by the light. The silhouette of the shade projected on another surface or body is called a shadow.
The light is reflected by an object or surface in the opposite direction to the light source and with an opposite angle of inclination but this is a subject of a branch of Physics called Optics (very exciting by the way, at least for me), but we won't stop to analyze this now, perhaps we will see it in some depth when we study reflections in perspective.
This schema below shows how light travels from a certain light source to hit some objects and the consequent shadows that the lack of light causes on the opposite side. (The red arrows are not vectors, they are only intended to graph the bouncing effect of light on an object).
The sun also radiates light in all directions, of course, but the rays reach the earth from very, very far away and the sun is enormously large relative to the earth, so in many cases, we will consider the sun's rays to fall parallel on the objects and not radially.
Here below are the three cases when sunlight falls on an object on earth.
N, S, W and E are the cardinal points.
The rotation of the earth is from west to east, our perception is that the sun travels from east to west.
1
Sunlight falls perpendicular to our face (from right or left). It is in this case that we consider that the sun's rays fall in parallel.
2
The sunlight falls in front of us.
3
The sunlight falls behind us.
The other type of light that originates from a local point source, such as a light bulb or candle, will be studied later.
We will start today with the perspective representation of the shadows caused by the fall of sunlight on an object. In particular, we will first see the easiest case, which is when the light falls perpendicular to our face, that is when we consider the light rays as rays in parallel projection.
First case: Sunlight falls perpendicular to our face
This is a representation of a one-point perspective. The length of the shadow cast depends on the height of the sun in the sky which is given by the parallel rays falling on the top vertices of the cube and the horizontal lines passing through the bottom edges of the cube that touch the ground.
At the top right, at the eye level line, the vanishing point where the helplines that define the cube and also the length of the shadow converge.
On the left side, perpendicularly intersecting helplines indicate the position of the sun relative to the observer (us).
This one below is the rendering of an object placed on the ground in a two-point perspective. The principles are the same as in the previous example.
I wish you a very nice day and good exercise!
Also, thanks to @xpilar for making these initiatives possible.
Here are the links to the previous related posts.
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