Character Animation.

[JOSE DUENAS]

Hello...

We're doing a TV commercial with animated characters... And of course, we want to use Vray for render... using global Illumination...

We've done that for architectural visualization without any problems precalculatin every 10-15 frames an incremental irradiance map in a single machine and then sending to the network the whole animation reading the precalc GI..

I've read in this forum too, that if you need to animate something, you have to go frame by frame calculating the GI... My question is.... Should I have to pre-calculate the whole GI (with the animated characters) in a single machine to avoide flickering (every single frame)?? an then send the animation with this precalc GI?? or is a valid option to send the whole process to some renderfarms??

Are there some tips to speed up the process?? Maybe separating the character from the scene in different renders?? but in this case... you don't have the scene contribution to the lightning of the character.....

Thanks in advanced, any tips and suggestions will be highly appreciated...

Jose Luis.

[richard_rosenman]

Hi Jose.

I've done numerous spots with characters and Vray:

http://www.richardrosenman.com/marinela.htm

http://www.richardrosenman.com/whitehall.htm

You'll find some useful info in each of these pages, but also here are some more tips.

If your scene has a camera move, exclude the characters and render with a presaved irradiance map.

Render the characters on a layer of their own, with single frame irradiance map computation.

Because the characters are rendered on a seperate layer without the environment, a nice trick is to use the rendered environment as a lightmap - this ensures the environment color is used on the characters.

Reflections, highlights, shadows are always rendered on seperate layers for maximum compositing control.

For lighting the characters, I usually use a traditional lighting rig, with single frame global illumination (irr map) and image based lighting.

Hope this helps.
If you have any other questions, just ask.

-Richard

[nildoe]

Hi richard...

How d u render the environment to be used as a light map? sorry if this is a newbie questio but i just wanted to know if there are any special steps to take in order to achieve this...also when u mean use it as a lightmap d u mean like using it as if it were an HDRI?

Nil

[vance3d]

Richard,

the success of your work flow is apparent in your end results. I greatly admire the look you've able to achieve in the commercials you've worked on.

Could you expand upon the character lighting a bit. I lost you when you mentioned you were using a singe frame irr map with image based lighting in addition to your traditional light set up. Are you saying that you are adding a few key lights to the fill generated by the gi image.

thanks

V miller

[JOSE DUENAS]

Thanks for your answer Richard....

I agree that your work is really great... Exactly what we're looking for... But also I agree with the questions that have been posted.... Could you please explain a little deeper???

Two more things.... When you render the characters with a single frame Irradiance map.... should you render it in a single machine??? or you can have network rendering without flickering with more computers???

The second question a little bit of topic... How did you did the water material in the marinela clip?? it's really great.....

Thanks again,
Jose Luis.

[Dman3d]

For several shots involving camera moves, pre-calculated global illumination irradiance maps provided flicker-free animation sequences. As usual, shots were split up into various layers to expediate rendering, including background pass, foreground pass, character pass, shadow pass, highlight pass, reflection pass, volumetric pass, and sometimes even a GI pass for realistic contact points of the character's feet on surface planes. The final lighting was a combination of image-based lighting, global illumination lighting, and traditional lighting techniques.

Richard, could you expand on this? I am not sure how you pull this off.

[richard_rosenman]

Hey guys.

I will do an in-depth, detailed write-up regarding this either tonight or tomorrow night and I'll post the link as soon as it's ready.

-Richard

[Dman3d]

That would be most appreciated, thank you!

[vance3d]

I'll look forward to that!

V miller

[richard_rosenman]

Hi guys,

Well, I didn't really get a chance to do a proper write-up (which I still intend to do) but in the meantime, the following should explain some of your questions.

Basically, I had to do a great deal of testing with Vray for character work as we have recently finished a 6 minute fully computer generated short film featuring a character and an indoor environment. To do a full GI render in one layer, the rendertimes exceeded 2 hours/frame. Even with Photon mapping I wasn't able to get things to speed up AND retain a good image quality. It was this that led me to figure out a faster method of rendering such projects.

The bottom line is that characters must be rendered using a single frame GI calculation. This is because characters move and every frame of the GI lighting is different and therefore has to be re-calculated. This is different from a camera move fly-by in which the background does not move and one can therefore pre-render the irradiance map at every n'th frame and then render the sequence over a network.

Now because characters must be rendered with single frame GI, the fastest method for doing this is to exclude all other geometry from the scene and render ONLY the character. This is nowhere near as accurate as if you rendered the character with the room "Not visible to camera" for instance, where the character would therefore interact with the environment lighting. However, this is also an extremely fast render. The problem is, if you render the character by itself, on it's own layer, how do you make it interact with the environment lighting?

One solution which I find works well, but is not necessarily accurate is to use the rendered enviroment as a lightmap. Some of you have asked what this means. Lets take a scene example in which you have a character in a blue room with red cast lights. First, hide the character from the room and render the room as a layer of it's own. For this, you would render it with all the bells and whistles (GI, Photon mapping, whatever). If there is a camera move, you can prerender the irrandiance map every nth frame and then render the entire sequence over a network.
You now have your background layer done.

Now you want to render your character. First get rid of all the room geometry in the scene (hide it like you did with the character) and unhide your character. Note, that you will keep exactly the same lighting set-up you used for your background (ie. the red lights) as you obviously want the character to be lit from the same direction, intensity, color, etc that the room was lit with.

Next, because the room is hidden, the room environment lighting will not be cast onto the character. You can fix this by using the rendered image(s) of the room layer and dropping it into the "Environment" slot (for GI) in the Vray render menu as you would with an HDRI. As with any environment map, make sure it is set to 'enviroment', not 'texture'. Now turn on GI and do a render.

You notice that the character is now lit with the background colors, as well as the scene lights. The first problem that often arises from this is that the combination of the scene lights with the background map GI is too strong and your character gets blown out. This will require minor light tweaking such as lowering the intensity of the main lights, as well as the GI Map.

The second problem you will notice is that the character is lit with the background map as if the map was 'projected' directly on top of the character. This means that if you had a red square in the map, the red square would be projected onto the character and this is clearly visible, especially when the character moves throughout the environment. There is a fix to this.

Blur the crap out of the background. The reason is because you are not interested in the background details - you only want the background colors to be used for your character. NOTE: Turning up the blur in the material DOES NOT blur the environment map even though it shows it blurred in the material editor! The right way to do this is to bring the map into Photoshop and put a Gaussian blur of 70+.

There is no specific way to do all this. It changes depending on the scene. For example, if you have a camera move that moves from one end of a room which is blue to the other end of the room which is red, you would use the rendered sequence of the background as a light map because it is important to reflect the change in the background on your character.

By doing it this way, you can have blazing fast GI renders of your characters since there is hardly any other geometry in the scene complicating the GI solution. To give you an example, I usually use a GI min/max resolution of -2, 0 for final production renders with an aliasing of 0,2. With these high settings, the GI map calculation often takes no more than 5-10 minutes. I usually allow myself a maxium of 30mins to 1 hour for final frames with full GI, reflections and motion blur.

There are a whole bunch of other things you must keep in mind when rendering over a network such as rendering your irrandiance map on one computer only and then making it accessible by all render nodes.

Other things which help integrate your character into the enviroment is to use your pre-rendered enviroment map as a reflection map as well. Once again, remember to turn it to 'environment' not 'texture' and make sure it is on 'spherical'.

There are also occasional exceptions to the above case. For instace in Robaxacet:

http://www.richardrosenman.com/whitehall.htm

There is a scene in which the characters come running out of the house. The inside of the house is lit with warm yellow lights and the outside is lit with cool blue lights. It would have been impossible to create a convincing effect of the change of light using the pre-rendered background map as a lightmap because basically it would light the characters on the top of the screen warm and those on the bottom of the screen cool. In addition, the fact that warm light floods the cool lights when the door is opened only complicates the scene. In this instance, it was necessary to build the front of the house with dividing walls so that the interior which was lit with warm Vray lights would contain the light and separate it from the exterior cool Vray lights UNTIL the door was opened. Naturally, having included geometry in the scene that is not visible to the camera but still contributes to the GI solution slows down rendering quite a bit.

Ok, I think this post is long enough. Hopefully I've clarified a few things for you guys.

To sum it up, the above method is not necessarily physically accurate but it looks good and it renders damn fast. And in the end, that's all that matters.

I still intend to do a proper write-up regarding this which I should have ready within a week or two. I'll post it as soon as it's ready.

-Richard

[jujubee]

Proper write-up? What you descirbed is already fantastic! That is great technical information and well-written. It must have taken you a long time to write. I just had a couple questions.

-I gather that you have to add an image for every other slot in the environment map when a scene is doing a fly-through. Is there a way to render out a low-res .avi, run it through after effects with a blur, then put the .avi in the environment as a substitute. Or is that just knocking up the render times again? I'm just wondering if that would work as well.

-This may be a newbie question. I'm also assuming that you can take your images and blur the whole directory in photoshop with a macro. Should save on time right?

-jujubee

[richard_rosenman]

Hey Juju.

Yes, if you want to save time, you can render a low res version of your background, blur it and use that for your lightmap. However, since you will be rendering the background in good sooner or later anyways, you might as well use the better one.

As for blurring the entire directory of textures, I suppose you could do that but you can usually use one lightmap to light various elements ie. characters, props, etc.

-Richard

[vlado]

You can also put a camera approximately where your character is, render a spherical view of your scene, save it as a .hdr file and then use that .hdr file to light your character.

Best regards,
Vlado

[zerofractal]

How would you go about doing the shadow of the character on the floor?

For ex. I want to produce a moving vehicle on a street. the only thing that has significant movement is the vehicle, but it does not substantially affect the lighting of the scene except for the indirect illuminated shadow on the floor. If i prerender the scene and the street, how can I tell the pre rendered street to get darker under the vehicle?

Hope the question is not too stupid.

[dbuchhofer]

Thank you for sharing your insights Richard..

I have a few questions about how you are splitting the scene out into layers.. I've begun to do this on a few jobs here for ease sake of editing and re-rendering. Are you doing these in another renderer and using elements? The only way I can think of to do this easily in vray is to save out to a RLA/RPF and to disect it in post into its various layers.. Second, any tips on keeping track of all of this throughout the various inevitable revisions on a given job?

Zf: You want to have a ground plane under your scene that is a matte object, set to accept direct light shadows.. nd set to affect alpha I believe.. (Options found in the Render dialog under Settings -> Object Settings..)