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Postby Wb_draws » Fri Sep 07, 2018 5:55 pm

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  Wb_draws
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Subject title: Lightning exercise

Hi,

I would really appreciate some comments to this piece. I am just starting to study lightning and rendering from imagination, so it would really help to know if I am going in the right direction or maybe missing something. On the right part I tried adding some simple pattern, but I am not sure if it reads properly

Thanks a lot :)

Image

 

Postby bosinpai » Fri Sep 07, 2018 10:07 pm

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Here's what Blender says:
Image

Looks like the middle cylinder part has to be lit as a cylinder, not as a sphere ;)

Note: lightNing -> lighting ^^

 

Postby Josephcow » Fri Sep 07, 2018 11:37 pm

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This is a pretty decent job so this is going to get very nitpicky, so forgive me. I do see a couple things worth improving.

- The form shadow on cylinders is always straight. The cast shadow may curve around the form, but the form shadow is always a straight line on the long axis.
- the small things protruding on the form should affect the shape of the form shadow. You kind of just put one sweeping shadow over the whole semi-circle, which is definitely a good way of thinking about the lighting generally, but realistically there will be interruptions in that shadow from the smaller forms within it.

- I can't really figure out the rim you are putting on the right semi-circle. I could see how it could be that way, but I feel like you really want it to be a cylinder, so it's like a rim of a bowl. In any case something's weird about the perspective there.

-I'm a big advocate for flattening the shadow, but since we see a brightly lit plane right under the object, we expect there to be a certain amount of reflected light.

- start thinking about transition size, and being more careful about it. The gradation from shadow into light is generally a lot shorter than we assume.

So this is how it would look to my eye, but keep in mind I'm not a machine and I can't do it perfectly either.
0581_DDBB_D316_416_B_AEF5_D80_A0_A14_F12_E.jpg

 

Postby Wb_draws » Sat Sep 08, 2018 11:27 am

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Thank you guys! This is helping a lot and hopefully it will prevent me from making the same mistakes in the future :)

bosinpai wrote:Here's what Blender says:
Image


This is really helpful :) So I guess my cast shadows and reflected light need some more work

bosinpai wrote:Note: lightNing -> lighting ^^


Well, that is embarrassing

bosinpai wrote:Looks like the middle cylinder part has to be lit as a cylinder, not as a sphere ;)

Josephcow wrote:- The form shadow on cylinders is always straight. The cast shadow may curve around the form, but the form shadow is always a straight line on the long axis.


This is the information I was definitely missing! This seems like a basic stuff, but I didnt know that

Josephcow wrote:- the small things protruding on the form should affect the shape of the form shadow. You kind of just put one sweeping shadow over the whole semi-circle, which is definitely a good way of thinking about the lighting generally, but realistically there will be interruptions in that shadow from the smaller forms within it.


I will try to take it into account next time. I wasnt sure how the pattern will affect the shadow situation, so I didnt change it to much, but you are right, I should be more careful with it

Josephcow wrote:- I can't really figure out the rim you are putting on the right semi-circle. I could see how it could be that way, but I feel like you really want it to be a cylinder, so it's like a rim of a bowl. In any case something's weird about the perspective there.


Do you mean that we should not be seeing the edge of this thing?

Image

Josephcow wrote:-I'm a big advocate for flattening the shadow, but since we see a brightly lit plane right under the object, we expect there to be a certain amount of reflected light.


I tried putting some reflected light, but then I dimmed it a lot, as it seemed too strong. I see now from bosinpai and your examples that area catching reflected light should be much bigger and more visible

Josephcow wrote:- start thinking about transition size, and being more careful about it. The gradation from shadow into light is generally a lot shorter than we assume.


So should I make harder edges between lights and darks? Or do you mean transition in the lights?

One last question - how do you figure out the cast shadow? In both of your examples they look quite different from mine. I have just drawn some lines parallel to the light direction and based it on that, something like:

Image

But I guess, that I could make these lines longer and then obtain something similar like you did. So the question is how to determine where is the point where these lines meet the surface?

Once again, thanks a lot!

 

Postby Josephcow » Sat Sep 08, 2018 5:23 pm

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Wb_draws wrote:
So should I make harder edges between lights and darks? Or do you mean transition in the lights?

One last question - how do you figure out the cast shadow? In both of your examples they look quite different from mine. I have just drawn some lines parallel to the light direction and based it on that, something like:

Spoiler: show
Image


But I guess, that I could make these lines longer and then obtain something similar like you did. So the question is how to determine where is the point where these lines meet the surface?



I mean the transition in the lights. In between the light and shadow is a small transition which is essential. But it isn't a huge gradient.
On second thought about the shadow, I was wrong. It should curve, but it should go in the opposite way that you have it. It's always good to do simple forms from life to keep making observations about how it works, looks like I need to do a little more of that, too.


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