Tag Archives: effects

Advice

Why you need compositing in your 3d life

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Recently I’ve been retraining in Maya and giving myself extra alone time with the Arnold renderer from Solid Angle.
I decided to use this as not only an opportunity to find out how my Softimage lighting and rendering skills translate to Maya, but to show how basic compositing is something that every 3d artist should embrace if they don’t already.

One thing which has surprised me again and again is how little students and graduates of 3d courses are given a grounding in understanding what goes into their image and why it’s beneficial to use the compositing process as part of their workflow. Some students are even penalised for not showing their raw unenhanced render, having points deducted for daring to composite. To give a parallel, this to me is like a film photography student handing in negatives and no prints. The job is half done.

This won’t be a tutorial, more a pointer in the right direction for those who are starting out.
The example I use, a still life of a bowl of fruit, is a model from the very first lighting challenge hosted over at CGTalk. The files and others are downloadable at 3dRender. The model’s pretty old now so it’s not especially high detail but is still sufficient to show you what I intend to.

After a bit of setup in Maya and throwing on some pretty rough textures, here’s the beauty straight out of Arnold:

Beauty renderer

It’s lit with 3 lights; A cool exterior light, a warmer interior light, and a fill for the shadow in the middle. On their own, the images appear like this:

Lights Contact Sheet

These images can be added together in any compositing software and they will give exactly the same result as the beauty above, to the extent that a pixel on the beauty will be exactly the same colour as when these three images are added together.

Each of these images is itself a composite image. Arnold, Mental Ray, Vray and other renderers consider many different material properties when returning the final colour for a particular pixel. Each property can be saved out as an image itself and added together to form the final image. In the case of the beauty itself, these are the images that I’ve rendered out of Arnold:

Component Images

Again, added together, these form the same image as the beauty above perfectly.

(A side note here: A few component images are missing, including reflections, but were missed out of this contact sheet as they are entirely black. As none of the materials are reflective in the traditional sense, the reflection image is returned as black, whereas the direct specular contains highlights that mimic reflections. Arnold is peculiar in that it can consider reflections in 2 ways and transparency in 2 ways, depending on what is trying to be achieved.)
 

So what am I getting at here?

Here’s the beauty again:

Beauty renderer

Now here is a warm, evening setup:

Evening

And finally, a night lighting setup:

Night

All three use the same component images, composited together in different ways: For example, tinting the lights, changing the intensity by blending the images with varying opacity, or even desaturating the key light to achieve a moonlit interior effect. On the night lighting I’ve changed the apple using a matte together with the specular & sss channels from the fill light. It was too bright and waxy. I could have re-rendered the 3d perhaps, but a tweak in Nuke was a lot more efficient.

The compositing process, even at this basic level, allows for flexibility from the get go. Where clients are concerned, flexibility is key. When passing work by a client it’s inevitable that changes will be requested and often they are something subtle that can be achieved in the composite. If you try to achieve that yourself using only 3d solutions, the render times will get long, especially when working on tv or film. Ordinarily I work alongside compositors and it’s up to them to do compositing tweaks whilst I work on a new shot or more substantial alterations to a current one.

Similarly, when first lighting a shot, working with many rendered channels, including additional ones of your own creation, is a rapid method of figuring out whether your setup is indeed heading in the right direction. Using the same component images for multiple looks is a time saver too.

One thing to bear in mind is once you know which channels are likely to be needed, it’s time to stop rendering the others as these can fill up hard drives quite nicely.

In short, stop tweaking your 3d scenes asap. Render out your initial lighting setup and see how much can be done in the comp. It isn’t cheating; It’s part of the process. It allows you to render the shot out, pass it on, and start a new one. Ultimately it will help your relationship with compositors who like to know what’s going into your image and what they need to add, plus [perhaps I shouldn’t say this, but here goes] it will make you more employable.

Video

South Bank Show Trailer

A few months back I worked on a trailer for the South Bank Show, featuring Melvyn Bragg walking through the Leake St tunnel under Waterloo station. Bragg was shot on a greenscreen, with the environment being recreated in Softimage by myself and fellow freelancer Rasik Gorecha.

The obvious question there is why? Why can’t Mr. Bragg just go into the tunnel and we shoot it there, huh? Well, there are a few obvious answers to that. The tunnel, itself a road with access to a car wash half way down, is dank, contains certain undesirable types Mr. Bragg would probably best steer clear of, and is continually in flux thanks to it being one of the few areas in London where it is legal to graffiti. It’s also not the most comfortable of places to sit around in for long hours on a shoot. The other reason is that lots of the graffiti was to be replaced with animated posters and artwork featuring well known faces from the arts. That process is a lot easier if created digitally and lit using indirect lighting solutions.

My input on this was twofold. Firstly I set up the lighting in Arnold. After an hour or so of experimenting, the solution found was to place shadow casting point lights in the ceiling under about half of the strip light fittings, plus a spot light at either end of the tunnel. Additional fill lights were used to brighten up the nearest walls. The lights in the walls toward the back of the tunnel are merely textured models and not actual lights.

One of the things with a Global Illumination solution like Arnold is that it can lead to fizzing. One solution to lighting this tunnel would be area lights. This was ditched as a plan extraordinarily fast as it led to lots of noise, plus the modelled lights themselves act as bounce cards essentially negating the need for area lights at all.

Rasik had the majority of the modelling done by the time I joined in the project but was yet to embark on cables. Whilst he set up initial texturing, I became cable monkey. I modelled cables and brackets, trays for them to run along, pipes and all sorts. It took a few days of continually modelling cables before I’d finished them. Simple stuff but it really added to the believability.

South Bank Show Trailer

The top of the two images above is the model with finished textures and below that is the finished lighting.

The final trailer is not as it appeared on Sky for 2 reasons. They added their own logo at the end, naturally enough, and they own full copyright of the sound bizarrely, so mine’s a silent movie. Add your own ragtime soundtrack as appropriate.

Video

The Bible Series – VFX

Recently in America, The History Channel broadcast The Bible Series, knocking American Idol into the weeds for ratings. The real reason of course to celebrate this fact is that I worked on VFX for this, along with many others hired by / working at Lola Post, London.

There were hundreds of shots. As the series covers many well-known events that are either epic in scale or miraculous in nature, it’s hard to cut corners with this kind of content.

One of the advantages of VFX is the ability to extend sets or create new ones. The most used model shared amongst the 3d crew was that of Jerusalem. It was originally an off-the-shelf-model of a real scale model, intended to be seen from a distance, so it needed to be tweaked and improved upon where appropriate on a shot by shot basis. With so many artists having touched the model at one point or other, the lighting setup, materials and textures got improved to the extent that once composited, the shots really shone out. Many of the shots I did for The Bible featured Jerusalem, either as an entirely CG set or an extension tracked into existing footage.

One story that is covered in the show is that of Moses parting The Red Sea, with the Israelites being chased by Egyptians through the parted waves. The shot I did for this sequence is a slightly top down shot, following the fleeing crowds through the freshly created gap in the ocean. To achieve this, I effectively split the 3d ocean into horizontal grids and vertical grids. The horizontal grids were simulated with aaOcean in Softimage. The vertical ones were distorted to represent the sea walls, textured with composited footage of waterfalls running upwards. The join where the two sets of grids met was blended using a matte and Nuke’s iDistort node. Softimage’s CrowdFX was used for the fleeing crowd. Twirling smoke elements were added once passed to the comp.

An advantage of Softimage’s ICE simulation system is that making a convincing cloud or mist is a fairly straight forward procedure. I was tasked with creating a storm over Jericho, a swirling mass of cloud and debris that had to look huge and imposing whilst looking down through the eye of the storm.
With clouds, water, and many other fluids, scale can be half the battle. A large wave only looks large if surrounded by smaller ones, a cloud only looks like a huge ominous mass if seen as a collection of smaller masses, but go too small and the effect is lost entirely. In the case of the cloud, if too many small details were apparent it very quickly seemed fluffy. Cute a storm is not. Once the cloud’s scale was correct, there was the issue of it having to spin, distort and generally seem organic. Handily ICE has a node for rotating clouds around points in space so that solved that one. The distortion was shape animation applied to a lattice attached to the cloud.

The rest of my involvement on The Bible was tracking shots in PFTrack and adding in set extensions. Most of the 3d content was rendered using Solid Angle’s Arnold Renderer.

The shots I mention above, along with a few others, are now online in my updated 2013 reel.

For further details on VFX in The Bible, check out FXGuide’s feature on Lola’s work.

Announcements, Video

Brand New Showreel!

The work in the following reel is created using Softimage, Terragen, Nuke and PFTrack.
Text in the bottom right shows what I created for each shot.
See PDF for further details.
Download PDF shot breakdown

Edited on 15th Oct – Now updated with work from The Bible Series and How To Build a Planet

Announcements, Video

Waking The Dead continues…

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gemma

Following on from the previous post, this week’s episodes of Waking The Dead on BBC1 focussed on the story of Gemma, a girl raped twice then thrown off a bridge, and somehow surviving with a few broken bones and a shattered pelvis.

I worked on one shot for this, the falling stunt Gemma. A digital stunt double works out cheaper, and safer than a real one.

Being how she is seen at a distance I was able to get away with modifying a pre-existing female model straight out of Poser. I reduced the detail level to something managable, altered the overall shape to match the adjacent shots and set about animating using a slightly modified default rig in Softimage. Once that was cleared as being fine, the hair and clothes were added, the whole lot rendered out and passed on to Sascha for compositing.

[no longer on iplayer]