View Full Version : Realistic Shadows


jvr
12-16-2007, 06:46 PM
Hi all,

Very often, I've got to do or redo the shadow of an object. A realistic
shadow, not a flat drop shadow.

For example I've got to remove the background of a table and create
a new realistic shadow for the table agains a white background.

What method do you use to create this shadows?

What would be your steps to make the shadow of a table or a car? (two samples attached here)

Looking real studio pictures of a car, I noticed that the wheels have one strong shadow and the car gives a different shadow.

What's the PRO method?

Thanks in advance!

pixelzombie
12-16-2007, 08:10 PM
i will usually make at least 3 different layers for the shadows:hard shadow, soft shadow, cast shadow and then see how it looks from there depending on how the original image was lit...

Enkay
12-16-2007, 09:28 PM
I'm not sure how the pros do it but a few years ago I was into making special effects on home videos... When I added an object to a scene and needed it cast shadows I would usualy do it in a 3D software. I would render the shadow only and lay it over the video.

You don't need to be very good at 3D modeling to get a realistic shadow this way. You just need to replicate the basic shape of the object and figure out where the light should be coming from.

Probably not the answer you were looking for but I figured I'd throw it in anyway.

cli
12-17-2007, 01:56 AM
hi there's different approach to shadow creation most of times brushes is all you need other time you have to recreate the form of the obj distort and fade it when you use brushes pay attention to "banding" get rid of that with noise...

All you need is "Commercial Photoshop Retouching In the Studio" of Glenn Honiball a masterpiece for me :)

jvr
12-18-2007, 04:57 PM
Thanks pixelzombie, that's why I try, but with complex objects I'm not always sure if the perspective and distorts are ok.

Enkay, what 3D program do you use for this task? One time I wanted to use Maya to do a car shadow, but was to much for me. I'm on a Mac, do you know if there is a friendly program to do these shadows?

Thanks cli, will check that book.

pixelzombie
12-18-2007, 05:11 PM
if you're not sure about the perspective, you may want to learn about finding the vanishing point in an image and using that as a guide for making your shadows...

Enkay
12-18-2007, 09:16 PM
Thanks pixelzombie, that's why I try, but with complex objects I'm not always sure if the perspective and distorts are ok.

Enkay, what 3D program do you use for this task? One time I wanted to use Maya to do a car shadow, but was to much for me. I'm on a Mac, do you know if there is a friendly program to do these shadows?

Thanks cli, will check that book.

Unfortunately I've been out of 3D modeling and special effects for a few yers now and I'm on a PC. I would really have no clue about some of the "easier" programs you could use but I'm sure there's some out there.

Back then I used 3D studio max version 3.1 If I recall correctly. It's not even installed on my PC anymore as I don't do anymore compositing work. The learning curve is a little steep at first but if you have a lot of "shadow" work to do it might be worth it to invest a week or two in knowing how to use the software as you can get some very nice shadows quite easily once you get the hang of it.

I had even written a tutorial on compositing shadow for video back in the days but I have no clue where that tutorial can be found now!

I'm not saying it's the best or easiest way, but it's one way to do it. If you want to find out more there's a very good 3D studio max forum where you could ask for further information on how to do it at http://www.maxforums.org

Dave.Cox
12-18-2007, 10:06 PM
Yes 3D studio max can generate shadows, but to do so, you have to create a model first. And even then, I find that I usually have to touch up the shadows in photoshop, after I finish the render. I think for your purpose, you should look at learning how to create your shadows in photoshop. The are several ways you can do it, and its worth learning the techniques.

jvr
12-19-2007, 04:37 AM
Dave.Cox, what techniques/ways do you mention?
Do you know a book or tutorials where I can take a look
at those techniques?

pellepiano
12-19-2007, 06:41 AM
The shadows will vary a lot depending on the lighting setup. Making believable shadows are very hard ( at least to me ). The 3d method seems like a good method.

punkjumper
12-19-2007, 08:42 AM
hoping I'm not breaking any site rules by linking to another forum but I link to this forum all the time so I guess its fair :) anyway this is a method that is very good. make sure you scroll to the right to see all the images.

shadow tut (http://www.worth1000.com/stories/thread.asp?cid=12&eid=312424)

Dave.Cox
12-19-2007, 05:49 PM
An overall good book for many techniques, including shadows is How To Cheat In Photoshop by Steve Caplin. It focuses on the art of realistic montages, and is very well written.

jvr
12-19-2007, 06:55 PM
Nice tutorial punkjunker!
This tutorial works with objects over the ground. There's a lot more
work to do when the object stands with legs, wheels, etc.

dvaught
12-20-2007, 10:39 PM
Photoshop has a shadow layer effect... just kidding, don't use that.

Being able to visualize what it is supposed to look like in real life is key. Make as many layers as needed to replicate and rob as much information as possible that was caught by the camera. Some times I have 2 layers, some times I have 20. I do all shadow work in Black only then turn off all layers except my shadow layers and duplicate my black channel (working CMYK). Add 3 points of noise to the channel (kills banding), push 3% off bottom of curve and pull 3% off top of curve to negate the noise added to pure white and pure black of channel. Make channel a selection, make new layer and fill with black only. I then delete my "working" layers so I am let with one shadow layer that is free of banding. If I need to add reflected color or want to go to a 4 color black near the object casting said shadow because it may need to be darker than black only will allow, I will create a new layer above that is using the shadow layer as a clipping mask, set to multiply and paint to desired effect. Convincing shadows are difficult to do.

Also note that shadow become more diffused and less dense the further away from the object that they are.

This is an example of robbing existing data. http://dvaught.com/portfolio/general/general_03.html

Here is are examples of creating what I would think would occur naturally
http://dvaught.com/portfolio/general/general_04.html
http://dvaught.com/portfolio/illustration/illustration_01.html
http://dvaught.com/portfolio/illustration/illustration_02.html

Alison
12-21-2007, 04:13 AM
One of my favourite photoshoppers is Bert Monroy - he has a short video tut on shadows - HERE (http://revision3.com/pixelperfect/shadows)

pellepiano
12-21-2007, 06:55 AM
Funny that he reduces the size of the shadow. Shadows can never be smaller , only more diffused or bigger than the object casting them.

jvr
12-22-2007, 01:09 PM
Thanks dvaught, your samples are great!

Alison thanks for the link. Nice tutorial. As pellepiano noted
I'm not sure why he reduced the size of the "wall" portion of the shadow.

I still would like to see what a pro does with a car or a furniture...

dvaught
12-22-2007, 11:25 PM
Thanks dvaught, your samples are great!

Alison thanks for the link. Nice tutorial. As pellepiano noted
I'm not sure why he reduced the size of the "wall" portion of the shadow.

I still would like to see what a pro does with a car or a furniture...

I have quite a few examples of cars that I can send you via e-mail if you'd like. david@vaughtstudio.com

Alison
12-22-2007, 11:37 PM
Funny that he reduces the size of the shadow. Shadows can never be smaller , only more diffused or bigger than the object casting them.

The pole or the tree ?

pellepiano
12-23-2007, 03:16 AM
He changed the size of the tree shadow.

dvaught
12-23-2007, 11:54 AM
It is in fact accurate for him to have made the shadow smaller as it went up the wall like that. Shadows get longer across a plain that is perpendicular to their position but when they hit a plain that is parallel like that it is relative to perspective.

I will add that in addition to blurring as he did the opacity should vary as well meaning the shadow should be both sharper and darker the closer it gets to the casting object. I also think that blurring the way he did is not a realistic way to do it because the shadow would get more diffused the farther away it gets. One blur added to a portion of the shadow does not achieve the effect that nature creates.

Enkay
12-23-2007, 05:05 PM
It is in fact accurate for him to have made the shadow smaller as it went up the wall like that. Shadows get longer across a plain that is perpendicular to their position but when they hit a plain that is parallel like that it is relative to perspective.

I will add that in addition to blurring as he did the opacity should vary as well meaning the shadow should be both sharper and darker the closer it gets to the casting object. I also thing that blurring the way he did is not a realistic way to do it because the shadow would get more diffused the farther away it gets. One blur added to a portion of the shadow does not achieve the effect that nature creates.


I really like the bedroom picture with the dog! Great job.