Showing posts with label sh040C. Show all posts
Showing posts with label sh040C. Show all posts

Friday, 14 June 2013

Sh040C Update

Here is an update on Sh040C.

I have cleaned it yesterday (by removing the rope and preparing the plate) but today I begun to add in smoke. I used my slower edited footage of atmosphere.

This is how it looks once the atmosphere is positioned, roto'd, layered and tracked:


However, this is not the look I am after because it looks very flat, slapped on top of the image, right in front of us - in our faces. POW.

So, I want to create the effect in which the atmosphere is wrapped around and intertwined with the ladder on the bottom third of the frame.

Therefore, I have to roto the ladder and composite it back on top:


I found the most effect way, instead of tracking the roto, was to simply animate the roto seen as it moves along a 2D track anyway (it is a very flat movement.) This meant that no unnecessary areas of the character were appearing on top of the ladder or other areas - creepy!

Even though this seems like a cool idea, it doesn't quite yet create the look as it doesn't make the smoke surround the ladder, it puts it behind the ladder. Therefore we need to see some smoke on top of the ladder. The best thing to do here is to take the merge of the smoke which is flat on top of the ladder and roto whispy shapes and areas of the smoke and then composite this again on top of the ladder roto.

This is the effect you are left with:


And this is the shot so far with some more colour correction testing:


What I wanted to create here was to darken it and bring out that contrast, but also not to lose the detail of the face within the darkness. In order to do this I lowered the gain of the whole piece but upped the gain of the shadows. Another notable tweak was that I also upped the gain of the highlights for more contrast and gave it a white cold and dreamy softness with a glow node. This adds to the feeling of the scene. And, this is just still in test mode and not final. I have not yet had a look at it next to the rest of the shots to see if there are any consistency issues, for example...

Initial Scene Preparations

First thing's first. Well, actually, it is calculating lens distortion, removing grain and motion tracking and such.

Here are a few examples of my initial preparations for a shot and how this applies to the final touches of Sh040C:

When using lens distortion, there are a few techniques. I prefer using either of two options: Nuke can automatically calculate - in a similar fashion to tracking - the lens distortion. The other is drawing points along straight elements in the scene and that will calculate if these elements bend due to lens distortion. I first of all use the former and use the latter to test if the lines are straight. If this does not work, I opt for the latter and draw the points manually along the lines.

This is an example for the lens distortion process:

This is the footage with lens distortion from the camera.

I have now applied the 'image analysis' and drawn a line with 'line analysis' in order to check it is has worked and the straight lines are indeed straight. They are.

Looking at this line on top of the original lens distorted footage, you can see that there is now a gradual distance from the line in the corners of the frame. This clarifies that the lens distortion has worked.

It is also important to clean out any noise from your footage if you are going to composite anything into it which may have no or different types and levels of grain.

Here is an example of removing grain in this shot:

Looking again at the original footage there is obvious noise/grain.

For comparison, here is the image once the Denoise node has been applied to the footage.

After the compositing of undistorted and de-grained footage/elements, it is important to re-apply the lens distortion:

Before. Notice the distance between the image and the end of the frame at either side.

After. Notice that gap filled and the rest of distortion now visible.

After. Now all of the smoke (subtle) have the same lens distortion to the originally shot footage.

The lens distortion makes everything like it should again and fills the frame correctly, as well as draw attention to any elements in the framing which the director designed or the DoP chose to bring out in the shoot, along with the elements that have been composited (I believe that it is good to place things in the composite considering the later lens distortion to make sure it looks right.)

And, re-graining:

By sourcing a flat area of the original plate (such as the concrete), using the F_Regrain node, it gives me an idea of grain. But, it always seems to require changing the grain size and amount by looking at the original footage again to use the eye to match it as best as possible.

After.

This is my process so far, regarding the first few cases of using the very effective method.