How to calculate the shadow direction, size, and transparency?

Question

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 timewith the same light source in the same position, exactly the same shadow willbe 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.

Answer 1

You don't need any precise science here, it is a drawing - an art form. If you do enough observational drawings you would develop a pretty good sense of haw a shadow would work and how dark it should be. Besides, you can always set up a still life, or get a model to eliminate any guess work.