PDA

View Full Version : Meet the Art :: Danny Dimian


PaulHellard
09-24-2009, 06:15 AM
http://features.cgsociety.org/stories/2009_09/cloudy/cloudy_mta.jpg

Danny Dimian
Shading Supervisor
Sony Pictures

Danny Dimian's creative approach to shader writing is on full display in Sony Pictures’ animated feature ‘Cloudy with a Chance of Meatballs.’ He was responsible for rendering and for the color pipeline as well as supervising the structure of shaders. And, he was a sequence supervisor for lighting and compositing on several shots.

But his career spans back thru 'Surf's Up', 'Spider-Man', and Monster House' as well as many other projects. He's a technical geek and an artistic journeyman.

Read his Artist Profile on CGSociety, right HERE (http://features.cgsociety.org/story_custom.php?story_id=5263), and come on back to ask Danny some questions.

To talk to the man himself, please feel free to post your questions and comments.

Please make a warm welcome to CGSociety’s Meet the Artist, Danny Dimian.

rianchen
09-24-2009, 07:16 AM
hi.. its our pleasure to meet you in cgtalk.

raylistic
09-24-2009, 09:37 AM
Hi Danny,
Great to have you here!

I would love to ask how do one get into the field of shader writing?
I understand a strong understanding of mathematics is required.
How do someone who is interested in shader writing starts?

I can actually see that Shader Writing is an interesting field because it has a good mixture of the artistic and the technical side.

Hopefully, you can give us some advice! Please! :)

Regards,
Raymond

firstsingle
09-24-2009, 04:14 PM
Saw this in 3D last night. Very funny movie. Sony, you guys did an excellent job with the steroscopic tech. Everything was like, right in you face delicious.

Danny, We both share common interests,
Computer science and art.

Question 1) What technical challenges did you face as far as shading and rendering times go. The food and skin look amazing. The sky and clouds are very alive when the town is happy.

2) Did you come up with new algorithms or did you use a lot of the 'old bag of tricks'? The film looks more raytraced than GI. Is this true?

I understand what you mean when you say:
"I’m happy not to have to choose"


Thanks Danny.

Osky
09-24-2009, 06:33 PM
Hi Danny, and welcome to the cgtalk forums. I wanted to ask for some advice as to what kind of work to place on a demo reel to land a position as a look-dev/shader writer in the film industry. Right now im kind of all over the place trying to get as much knowledge as i can creating different styles for my renderings, mostly photo-real thus far. You can check out my site www.shaderrooster.com. And I would appreciate any guidance as to what direction to head in creating my work to land the look-dev/shader writer position. Thanks

DannyDimian
09-25-2009, 01:35 AM
I would love to ask how do one get into the field of shader writing?
I understand a strong understanding of mathematics is required.
How do someone who is interested in shader writing starts?


Even if you're not able to go to a CG or animation school, there are many ways to get into shader writing, and with the many free renderers out there, anyone can start to play with writing shaders. To start with, focus on one renderer and its shading language. Renderman (or a renderman compliant renderer) is still very popular in larger CG houses like Disney, Pixar and Weta but many others are switching to raytracers such as Mental Ray or Arnold. I personally love using Arnold and a free version is available.

The act of writing shaders is similar to general programming so experience with computer science and writing software will also help. To do development work in shaders you should also have a good understanding of rendering algorithms.



I can actually see that Shader Writing is an interesting field because it has a good mixture of the artistic and the technical side.

Yes, although writing the shaders is fairly technical, the goals are artistic and you need to be able to work with fellow artists to come up with visual solutions. A shader writer also needs to be familiar with the vocabulary of the visual arts in general and especially photography.

DannyDimian
09-25-2009, 03:55 AM
Question 1) What technical challenges did you face as far as shading and rendering times go. The food and skin look amazing. The sky and clouds are very alive when the town is happy.

Hair and too much geometry, or rather too many polygons are typical problems you face with a ray-tracer and we also struggled with these issues. For hair, we control the number of hairs and their width depending of their size in screen space. This ensures that we never have hair thinner than a pixel and this keeps the number of rays down. Arnold (our renderer) also renders the curves directly so only the control points are stored in memory. This memory savings leads to greater spead since most raytracers end up memory bound.

The clouds were rendered with "SVEA" our in-house volume modeling and rendering package. This is basically a voxel renderer that makes use of deep shadows to speed up shadowing calculations.



2) Did you come up with new algorithms or did you use a lot of the 'old bag of tricks'? The film looks more raytraced than GI. Is this true?

I'm not sure we came up with any new algorithms, but perhaps some unique shaders or shader materials. The shader for the jello castle for instance, has controls that allow the lighter to control the colors and volume properties in a very artistic way. In this sense the shader is not very physically based, which is a departure from the typical uses of a ray tracer. You are correct that Arnold is a raytracer. If by GI you mean radiosity or other energy based rendering, no, we didn't make use of those types of GI.

prettyh8machine
09-25-2009, 12:18 PM
Hey Danny,

Just a few questions:

1. How much of your shader writing is done in a notepad vs a visual editor, such as SLIM?
2. What piece of advice (must-do sample shaders, exercises) for a wanna-be shader writer who works at a smaller studio on smaller projects where there is hardly any need for a new shader to be written from scratch, for actual production?
3. What are the key differences between a ray-tracer such as Alfred and a hybrid/scan-line renderer such as PRMan, from a production's point of view? Is there any obvious choice?

Cheers

Reality3D
09-26-2009, 08:49 PM
Hi Danny:

I am interested in the integration of Arnold and the shading pipeline
I recently saw in the OpenSource Imageworks webpage the Open Shading Language project. Nice to know that Larry Gritz was there. But the project is not yet online.

Have yo gone through the integration on this shading language with Arnold?. How it does compare to renderman.

Do you work on your own fork of Arnold or use Marcos Fajardo's releases?.


Thanks in advance :)

maxspider3000
09-27-2009, 10:21 AM
At first, am so happy that you agreed to share some of your experiences with us ...

and ... I didn't watch the movie yet, but from the trailers ... the colors, lighting and shading are really amazing ... amazing so far man ... you guys did a great work on it

I will come back later with some questions ... hope you a happy staying :D

Lolec
09-27-2009, 04:54 PM
I would love to work with arnold render, where did I find the free version you mentioned ?

question)

How are you involved in the look and feel decisions? i mean, are you dictated with the shader behavior and execute it or your decisions changed the overall look of the movie ?

Its a great movie! I think the shader work in the food is comparable to ratatoille. congrats.

DannyDimian
09-28-2009, 03:58 AM
I wanted to ask for some advice as to what kind of work to place on a demo reel to land a position as a look-dev/shader writer in the film industry. Right now im kind of all over the place trying to get as much knowledge as i can creating different styles for my renderings, mostly photo-real thus far. You can check out my site www.shaderrooster.com (http://www.shaderrooster.com/). And I would appreciate any guidance as to what direction to head in creating my work to land the look-dev/shader writer position.


As a shader writer you should highlight the material properties of the shaders that you developed. The lighting should be good enough to showcase your work. Animation is not very important, but you often have to move the camera or object to show the behavior and material behavior. This also shows that you've solved the sampling issues for the material. For photo-real work, it's always fun to see the real thing side by side with the cg and compare.

It's often effective to show the individual layers that the shader is calculating and how the final material is composited together in the shader. This "making of" helps explain how you came up with your solution, and what the shader is doing.

All the other things that make a good demo real still apply:
1. Put your best work first.
2. Include a real breakdown explaining exactly what you did, especially if many people worked on a shot.
3. Keep it short. 2-5 minutes is enough.
4. Taylor your reel to the position you're applying for.

firstsingle
09-28-2009, 05:57 PM
Question 1) What technical challenges did you face as far as shading and rendering times go. The food and skin look amazing. The sky and clouds are very alive when the town is happy.

Hair and too much geometry, or rather too many polygons are typical problems you face with a ray-tracer and we also struggled with these issues. For hair, we control the number of hairs and their width depending of their size in screen space. This ensures that we never have hair thinner than a pixel and this keeps the number of rays down. Arnold (our renderer) also renders the curves directly so only the control points are stored in memory. This memory savings leads to greater spead since most raytracers end up memory bound.

The clouds were rendered with "SVEA" our in-house volume modeling and rendering package. This is basically a voxel renderer that makes use of deep shadows to speed up shadowing calculations.



2) Did you come up with new algorithms or did you use a lot of the 'old bag of tricks'? The film looks more raytraced than GI. Is this true?

I'm not sure we came up with any new algorithms, but perhaps some unique shaders or shader materials. The shader for the jello castle for instance, has controls that allow the lighter to control the colors and volume properties in a very artistic way. In this sense the shader is not very physically based, which is a departure from the typical uses of a ray tracer. You are correct that Arnold is a raytracer. If by GI you mean radiosity or other energy based rendering, no, we didn't make use of those types of GI.

Thanks for taking the time to answer Danny. I've gotten just the answers I hoped for. Cheers.