<p>The <a href="https://crafts.stackexchange.com/a/153/44">CreationEdge answer</a> is technically superb.  For the benefit of your sensitive side consider the diminishing light and introduce reflected color.  The edges of your shadows should not be hard if you intend to present a realistic copy of the subject.  </p>

<p>For a pencil or charcoal work, soften the edges with your finger, tissue , or preferred tool.  The darkest region will be where the shadow touches the object.  After that, lights ability to bend will alter the degree of darkness and the shadow will fade at the edges.  </p>

<p>For painting, pastel, or colored pencil, understand that the surface on which the shadow rests and the object itself will reflect some color and contribute to the hew of the shadow.  Next time your out on a sunny day stand next to an object with a distinct primary color, like an automobile, and look for the car's color reflected in the shadow.  </p>

<p>I think this answers, at least part of, the transparency element of your query.</p>

CC BY-SA 3.0
2017-06-26T14:07:23.087Z
2017-06-27T00:17:01.523Z
2017-06-27T00:17:01.523Z
user2264
<p>Suppose I want to draw a shadow of X. How do I know what should be the EXACT </p>

<ul>
<li>size of the shadow</li>
<li>direction of the shadow</li>
<li>transparency of the shadow.</li>
</ul>

<p>Of course, it all depends on the light source. But how do I <strong><em>"calculate"</em></strong> it?</p>

<p>There have to be some formulae and measurements, because every time
with the same light source in the same position, exactly the same shadow will
be created.</p>

<p>So, how to calculate the shadow direction, size, and transparency?</p>

<p>This is about drawing. I intend to draw a shadow of an object on paper.<br>
You can assume a simple light source like a candle in your answer.<br>
Diagrams will be appreciated.</p>

CC BY-SA 3.0
2016-04-27T06:57:15.487Z
@CreationEdge please answer whatever you know.
Aquarius_Girl
CC BY-SA 3.0
2016-04-27T13:50:07.107Z
My few art classes used 'lines and angles.  not calculations.   "where is your light source?"  draw a 'line' from the source across the top of the shadow generator to the 'ground' or surface'
bowlturner
<drawing>
How to calculate the shadow direction, size, and transparency?
Aquarius_Girl
# How to calculate the shadow direction, size, and transparency?

(Asked by: username_0 on 2016-04-27)

Suppose I want to draw a shadow of X. How do I know what should be the EXACT

* size of the shadow
* direction of the shadow
* transparency of the shadow.

Of course, it all depends on the light source. But how do I ***"calculate"*** it?

There have to be some formulae and measurements, because every time
with the same light source in the same position, exactly the same shadow will
be created.

So, how to calculate the shadow direction, size, and transparency?

This is about drawing. I intend to draw a shadow of an object on paper.  
You can assume a simple light source like a candle in your answer.  
Diagrams will be appreciated.

**Tags:** drawing

> **Comments:**
> **username_0**: @CreationEdge please answer whatever you know.  
> **username_1**: My few art classes used 'lines and angles.  not calculations.   "where is your light source?"  draw a 'line' from the source across the top of the shadow generator to the 'ground' or surface'  

---

## 1 answers

### Answer by username_2 on 2017-06-26. Score: 3

The [CreationEdge answer](https://crafts.stackexchange.com/a/153/44) is technically superb. For the benefit of your sensitive side consider the diminishing light and introduce reflected color. The edges of your shadows should not be hard if you intend to present a realistic copy of the subject.

For a pencil or charcoal work, soften the edges with your finger, tissue , or preferred tool. The darkest region will be where the shadow touches the object. After that, lights ability to bend will alter the degree of darkness and the shadow will fade at the edges.

For painting, pastel, or colored pencil, understand that the surface on which the shadow rests and the object itself will reflect some color and contribute to the hew of the shadow. Next time your out on a sunny day stand next to an object with a distinct primary color, like an automobile, and look for the car's color reflected in the shadow.

I think this answers, at least part of, the transparency element of your query.


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