The problems begin when one day, that person decides to reproduce a landscape, for instance, in glass, or any other medium other than paint or pencil. They often/usually take out a photo, and copy it. BUT they have little or no understanding about how to create an image in two dimensions on a flat surface .....they have none of the useful rules and tricks that painters use. Sometimes they are happy with their results ...often, they are not but do not know why.
Well....Photos often "tell lies", because the camera is not as helpful as one might imagine, it causes distortions in perspective and space, it can flatten areas, it can alter colours and tones because it cannot read both the light areas of a scene and the dark areas, at the same time, with the accuracy of the human eye.
LOOK AT THESE TWO PICS. SAME SCENE! you cannot tell from the top picture that these are silver birch trees. but hey ....they are!!!!! You can see how lovely and slender the two semi-foreground trees actually are, while in the darker pic it is hard to see their shapes properly, and if you were to use that image, you might well produce thick and unattractive trunks on the left. And look how much texture in the foreground is hidden in shadow...the human eye would see it, the camera could not. Well, to be fair....it did...it was there but had to be revealed by manipulating the photo. Your eye does not need to be manipulated in this way. Finally, notice how the distant shrubs appear to be just as dark as the tree trunks, which, if created just as dark as the photo, the sense of distance would be impacted adversely.
So - does this matter, the fact that the camera is not so discerning as the human eye?
I believe so because
*An artist will adjust many of these problems by picking and choosing from a variety of tools and lessons he or she will have learned.
* An artist will leave out unnecessary items in a landscape - an ugly telegraph pole, for instance, or a black area of shadow because a) he can and b) because the pole/shadow does not help him to achieve the best result - it is not just inessential, it actually detracts from the scene.
*An artist will adjust the composition to improve the piece, to make it stronger and to achieve a better result than that offered by the photo. Or even, sometimes, in real life.
A non-artist will often, for example, create a scene with half sky, and half land..."because it balances". Well, actually, this is not the case...it balances badly! The viewer does not know what is important, the land or the sky. The viewer's eye jumps from one to the other. Not ideal.
This last comment is just one example of many. So the answer to "why do I need to know how to draw" is because it gives you the chance not just to be creative, but to be creative in the most effective way. It gives you opportunities to CHOOSE strategies for how you want your image to look and how you want others to feel when they look at it. And it strengthens the end result. Win win.
For the glass artist, who wants to reproduce landscapes in glass, I believe it is really important to learn something about drawing, and the "rules" of composition which have served painters so well for aeons. It is why I wrote "Creating Depth and Dynamic Design in a glass landscape", and sell this e-tutorial for just a few dollars. Have a look at my website tutorials pages: WEBSITE TUTORIALS (if link does not work, visit www.jackiesimmonds.com and go to the tutorials page. Keep scrolling down to find all the various tutorials!)