Matching Shadow Direction

Wallace · **Posted:** Mon Nov 06, 2017 2:07 pm **(#1)**

I've always has trouble with shadows.
:oops:

Working with the attached image below.
I'm trying to match the shadow direction,
given off by the cubes and add a corresponding shadow to the text.

Anyone know of a way to accomplish this?

Attachment:

text shadow.png [ 236.52 KiB | Viewed 5762 times ]

Attachment:

text shadow.xcf [1.19 MiB]
Downloaded 214 times

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4757

That will be difficult, for three reasons:

1) you need shadows on the cube and on the floor/background
2) as hinted above, there is no well defined surface in the background to put a shadow on
3) your letters are thin and lit sideways, so there is not much shadow...

And, Spanish-inquisition-style:

4) "GIMP" likely casts a shadow on "2.8".

Wallace · **Posted:** Mon Nov 06, 2017 3:36 pm **(#3)**

ofnuts wrote:

That will be difficult, for three reasons:

1) you need shadows on the cube and on the floor/background
2) as hinted above, there is no well defined surface in the background to put a shadow on
3) your letters are thin and lit sideways, so there is not much shadow...

And, Spanish-inquisition-style:

4) "GIMP" likely casts a shadow on "2.8".

Thanks ofnuts for your reply.
I guess I may need to change the direction of the light source,
and or the size of the text.

racer-x · **Joined:** Apr 15, 2017 **Posts:** 1826

Perhaps something like this? I used both the "Sheer" and "Perspective" tools on the drop shadow. First time I've used those tools actually...

Attachment:

text shadow.jpg [ 32.36 KiB | Viewed 5719 times ]

Wallace · **Posted:** Mon Nov 06, 2017 6:07 pm **(#5)**

racer-x wrote:

Perhaps something like this? I used both the "Sheer" and "Perspective" tools on the drop shadow. First time I've used those tools actually...

Attachment:

text shadow.jpg

Thanks for giving it a try racer-x.
:bigthup

I think I'm going to completty redesign the text and the light source.
To see if I can make it much simpler to create more accurate shadows.

Konstantin · **Joined:** Sep 20, 2016 **Posts:** 293

In my opinion this kind of effect is not really the domain of a raster editor as Gimp unless you have very good knowledge of lighting like a painter or work from a model.

I got into Blender a few months ago, because i was interested in the longshadow effect.
What i learned is that a big part of Blender is what is called "lighting a scene".
Its almost as making a film, but as a single image.
You can have a single light or many. Spotligts or directional lights. Reflection of the environment plays a role.
Etc.

Gimp doesnt have the tools to take such things into account.
You can draw a lamp or something as the symbol of the light on a new layer and that can help, but as soon as the lighting gets more extreme or complex, you will have problems.
Therefore i think lighting in Gimp is in the best case more a case of cliches or abstraction.

Wallace · **Posted:** Mon Nov 06, 2017 10:41 pm **(#7)**

Konstantin wrote:

In my opinion this kind of effect is not really the domain of a raster editor as Gimp unless you have very good knowledge of lighting like a painter or work from a model.

I got into Blender a few months ago, because i was interested in the longshadow effect.
What i learned is that a big part of Blender is what is called "lighting a scene".
Its almost as making a film, but as a single image.
You can have a single light or many. Spotligts or directional lights. Reflection of the environment plays a role.
Etc.

Gimp doesnt have the tools to take such things into account.
You can draw a lamp or something as the symbol of the light on a new layer and that can help, but as soon as the lighting gets more extreme or complex, you will have problems.
Therefore i think lighting in Gimp is in the best case more a case of cliches or abstraction.

Yes I understand this and I have used Blender in the past.
That's why I'm going to reevaluate the design and start over if need be.

Thanks for your response.
:bigthup

dinasset · **Posted:** Tue Nov 07, 2017 3:16 am **(#8)**

My try, Wallace (Gimp only)
(removed)

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4757

No reason for the shadow of the letters to be darker than the shadows of the cubes (and have a different direction: if the bigger cube had a shadow cast from the same light source as GIMP, its shadow would not be over the smaller cube).

rich2005 · **Joined:** Mar 04, 2011 **Posts:** 2446

The shadow from the cubes does not look correct to me. Just for general direction of shadows perhaps something like this. (raytraced in art-of-illusion)

Attachment:

28.jpg [ 26.66 KiB | Viewed 5633 times ]

dinasset · **Posted:** Tue Nov 07, 2017 10:09 am **(#11)**

ofnuts wrote:

No reason for the shadow of the letters to be darker than the shadows of the cubes (and have a different direction: if the bigger cube had a shadow cast from the same light source as GIMP, its shadow would not be over the smaller cube).

Correct.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4757

rich2005 wrote:

The shadow from the cubes does not look correct to me. Just for general direction of shadows perhaps something like this. (raytraced in art-of-illusion)

Typical British understatement...

iarga · **Posted:** Tue Nov 07, 2017 10:47 am **(#13)**

Wallace, maybe something like this. (sketch):

blue lines: don't do something here, they only give idee for perspective.
black lines: to find the light source. (with shadows of cube)
red lines: rays from light source

In this case the "GIMP" text shadows will be a bit boring.

iarga · **Posted:** Tue Nov 07, 2017 11:24 am **(#14)**

My above post doesn't work, because the original cube shadows are in another direction:

Green lines give shadow direction:

What kind of light source is used?

because some lightray-lines are intersecting and some are parallel:

What kind of perspective is used?

iarga · **Posted:** Tue Nov 07, 2017 12:38 pm **(#15)**

Wallace, are this videos helpful?

light source = sun:

Video from : www.youtube.com

But I doubt if this video is totally correct, because the sun is not a point light source.
Maybe this is better?:

Video from : www.youtube.com

other light source:

Video from : www.youtube.com

If there is an image with proper perspective and shadows, you can invert this proces to find the light source.

Wallace · **Posted:** Tue Nov 07, 2017 12:50 pm **(#16)**

Thank you for all your responses!
:jumpclap

You've all been very helpful.
I'm going to rework the image in GIMP and perhaps use Blender for the cubes,
text and shadows.
Then finalize the image using GIMP.

Thanks again for all the helpful suggestions!
:bigthup

iarga · **Posted:** Tue Nov 07, 2017 1:02 pm **(#17)**

Yes Wallace, Blender will solve this. :bigthup

(I'm learning also new things

)

Wallace · **Posted:** Tue Nov 07, 2017 1:08 pm **(#18)**

iarga wrote:

Yes Wallace, Blender will solve this. :bigthup

(I'm learning also new things

)

I haven't used Blender in quite some time.
Would need to take a refresher course,
before jumping into it.
It shouldn't be difficult to do.
Given that the elements within the image are pretty minor.

RJKD · **Posted:** Tue Nov 07, 2017 1:21 pm **(#19)**

My idea... :roll:

Attachment:

Wallace_text shadow.png [ 236.86 KiB | Viewed 2369 times ]

iarga · **Posted:** Tue Nov 07, 2017 3:15 pm **(#20)**

Something like this, made with SketchUp Make 2015, but in Blender it will be much cooler:

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