Jack Smyth, Brief 01, Altar Sequence, , DD1410, Visual Effects 1, Jamie Scott

Altar Sequence

Shot one:

This sequence is comprised of nine shots, this shot is to create a 'Hold Out Matte' around the dragons and an ornate lamp.

When the footage is first viewed, the camera work appears to be shaky, therefore the first thing that is needed for this shot is a tracker. This tracker will be used for 'Stabilisation'. What this tracking does is take away the shaky camera work, meaning any rotoscopes that are used should fit well in the shot with little to no movement, by changing the trackers properties to 'Stabilize'

Transform nodes had to be used to also enlarge the picture inside of the frame range, because when the trackers stabilise the footage, the outside of the footage will jump around to accommodate this new change:

The scale of the original footage has been sized out to keep the stillness the trackers have brought with their stabilisation.

With these trackers in place, the ornate lamp and dragon rotoscopes will be made for the shot, if the VFX artists this is passed on to wish to add a glow or particles to this piece as well as the inside parts of the dragons (Such as inside the tail on the left hand dragon), they can do so with the different beziers outlining the objects:

The same thing is applied to the ornate lamp in the middle, however with this middle-lamp, more beziers were placed, and given their own folders, for example, the individual knobs on the top of the lamp, the top of the lamp itself, and the sides independently. The dragons also have a similar process, with the two dragons being separated in the roto properties by their own files, this will help keep beziers in the right place should someone else wish to work on them.

 The rotoscope, trackers and transforms now in place, the rotoscopes will now fit the shot well, since it hardly moves due to the information the trackers picked up for the stabilisation. This is the final node tree of the shot, showing the two rotoscope nodes, and their corresponding trackers and transforms:

 Shot two:

Shot two in this sequence is a hold out matte of the girl facing the sky, in this shot we want to take out the blue screen in front of her, so that the effects artists may place any background clip or location they wish, in order to do this, keylights, lightwraps and beziers have been used to achieve this.

The rotoscope was brought in to make a 'bubble' around the girl, this bubble would then be useful for the keylights later on.

A keylight is then brought in to the shot to take out the blue colour in the background using a tool called 'screen colour', this tool is used to select the blue outlining the girl inside the rotoscope. The keylight is linked up to the rotoscope with a pipe saying 'Out matte', there are other parts of the keylight connectors that make this work fully, the out matte is plugged into the rotoscope, the inner matte is connected to the 'Inner keylight', a keylight that fills out an alpha of the picture (more information below), and the source plugged into the source footage. When this screen colour is used in our first keylight, the blue should turn to a black, meaning there will be nothing here except the girl that is rotoscoped:

 When a shortcut key is then used (A), the alpha can then be viewed. The alpha shows the girl in the rotoscope, and how the screen colour has taken out the vast amount of blue that was surrounding her:

In the screenshot above, you can see the girls alpha is not fully covering her, as there is a large amount of black on her left arm. If this black is seen, that means there will be transparency in our bluescreen, so an 'Inner Keylight' is brought in to solve this. The Inner keylights job is to fill the inside of the alpha, in this case, the girl.

The inner keylight clips the colours inward using a  'Dilate' to try to contain the alpha inside the girls outline, after which the 'clip black' is used to take away the residing black colouring that we have in the screenshot above, this fills out the alpha, thus the inner keylight is filling out the inside of the alpha:

With the inner keylight, the inside of the alpha is altered to fill out the inside, now the 'Outer keylight' must be used to fill the outside of the rotoscope. The outer keylight works in the opposite to the inner keylight, in that it is used to fill out the alpha, so that the outside of the rotoscope is filled out. When we combine them all, the inner keylights information will now not override the outside of our rotoscope, which may clip the girl, giving her a jagged edge around her alpha, and missing information:

The outer keylight tools are used to fill out the alpha, so the dilate in the properties is placed at 4.5, meaning that the keylight will make a 'halo' effect around our rotoscope:

Combined, the inner and outer keylights are plugged into our main keylight and rotoscope differently. The outer keylight is placed into the background, the inner keylight, has the original keylights 'Inner matte' plugged in. All of this information means our original keylight will have the inside of the alpha fully filled, whilst the outside will still retain the outside information of the girl we want to include into the blue screen:

In the final keylight, in order to use both of the inner and outer keylights, options must be selected in the original keylight, which is the 'InM component' and the 'OutM component'. These integrate the inner and outer keylights into our first keylight, which completes the final alpha, by choosing the alpha in the InM component, and the inverted alpha in the OutM component:

Now that our Alpha is complete with the keylights, the image for the background shall be brought in to complete the effect, and show that the keylights and the alpha work. Another image, a backplate of blue, has been reformated to fit the current shot is brought into our shot (Which is HD 1920 x 1080):

The backplate is ready for our rotoscope to be placed into, a merge node is used to do this, and, when connected to the foreground keylight and the background to the reformat node, which is linked to the backplate, the child should be shown in the image:

  With both combined, you can then add to this further by bringing in a 'Lightwrap'. This lightwrap is used to bring more of the backplates light across our girls rotoscope, which may make it seem to blend further with the backplate, because some of its colour is being spilled onto the rotoscope:

It may not be noticeable at first glance, but look at the hair in the screenshot above to the one previous, there is a small amount of light, wrapping around the hair, with a small amount of brightness outlining her left arm.

In the end of this shot, another backplate has been brought in to show the difference between a blue backplate and a red backplate, and the effects the different colours have on the original roto:

The final node tree has been laid out with backdrops so that anyone accessing this nuke script knows where the rotoscope and its work is, as well as where the backplates for testing the blue screen are:

Shot three:

 Shot three is a shot of the girls face whilst she looks outside of the window, the camera here is as shaky as the camera from the first shot, so on this shot, a tracker was used to track the girls eye and stabilise the footage:

Shot four, six, and eight:

Shots four, six and eight are all similar shots, and required a hold out matte for the children against the dragons and lamp, and separate hold outs of the dragons, lamp and children against the blue screen in the background.

Starting on shot four, a number of rotoscopes were introduced to matte out the children against the blue screen. The first was an outer matte encompassing the objects and parts that needed to be inside the shot, so for this the bezier was placed around them all, and a keylight was brought in:

 The alpha in this initial rotoscope is filled with holes, so an inner keylight is used to fill out the holes, as well as an outer. Doing this now will help save time when making the rest of the rotoscopes, as you can use the same information to fill their alphas in.

In this sequence, the inner and outer keylight would have been used from the previous bluescreen shot, and tweaked to suit the new shot, such as picking a new screen colour and differentiating the dilates and clip blacks:

 This shows the difference in the inner keylights between the previous blue screen shots. A very small amount of clip black was used in this one, and the dilate is also tweaked to -1.5 due to the high amount of colour you can see in the alpha. When this is then connected to the rotoscope, the alpha when the inner keylight is plugged in looks as such:

 After the inner keylight came the outer keylight, with the information already mainly being in the inner keylight, it is duplicated and changed to take out certain areas of the white on the floor, in particular, next to the dragons:

With the inner and outer keylight set up for the other rotoscopes of this shot, viewing the shot without the alpha still shows the ground in the shot, which will be taken out later with a 'garbage matte', or simply, a rotoscope in which its use in this shot was to take the floor from beneath the children and the lamps:

With this first rotoscope in place, other rotoscopes are created to refine the matte out with more keylights, using the screen colours to define what areas of the rotoscope that are to be used for the bluescreen. The next rotoscopes are of the dragons and the ornate lamp, the two children in the middle, and the child on the right, each given their own keylights, plugged into the inner and outer keylights, and carefully chosen with the screen colour tool.  The child which moves into the shot will be explained further below, as it would have to be handled differently from the other rotoscopes, to work alongside the garbage mattes:

These rotoscopes now in place, keylighted with inner and outer keylights, and workable against a bluescreen from knee-height up, the floor is now presented as a the main problem.

A garbage matte is used here to cut out all of the unwanted floor, and a keylight is brought in to further darken and distill what has been rotoscoped, so that nothing on the floor remained. The hardest task about using this garbage matte, is that if the rotoscope overtakes anything, it shall cut it from the final shot, so once this has been made and keylighted, it would have to be moved alongside the last child who walks from out of the right hand side of the frame:

In the keylight you can see that there are many dark areas and possible holes due to the fact the colour was picked from the floor, but because of where the rotoscopes are placed, this rotoscope and keylight will not effect any other part of the overall image, because in the final merge, it shall be given the pipeline called 'Mask', this is what makes it a garbage matte, as the name suggests, it masks out anything that is not desired in the shot. 

The girl walking into the shot is tackled differently from the other children, as the other children do not walk, or move much in the shot. The bluescreen mattes are of a singular colour of blue that was taken out with our screen colour, so they do not need changing. Their legs however, must be worked with the rotoscopes of the garbage matte. The girl entering into the shot had two different rotoscopes, one from the floor, to capture the bottom of her body, and a bluescreen matte out for her top half, the top half rotoscope again given its own keylight and plugged into the inner and outer keylights.

All of these rotoscopes and the garbage matte work together to take away the blue outside of the children, the lamps and the dragons. A similar process is used in the last shot to test this all against a back plate of blue and red, both backplates being reformatted as well, this is the final product of the working bluescreen rotoscopes, on the blue, red as well as the final alpha:

Before the final node tree is shown with all of its connections, the separate hold out matte of the children is made to fit around the children on their own. These hold outs were created last so that the hold out for the girl entering can be made quicker by using the garbage matte rotoscope and tweaking it to fit tightly along the girl as well as the other children:

 Finally once the hold out matte for the children were made, the lifetimes of these rotoscopes were altered to fit between the frames of these shots, so when they do get duplicated for the scenes and altered similarly, the rotoscopes do not interfere with each other (Rotoscopes that start later than 176 were used at different times, and possibly ended quicker, such as a rotoscope matte between the child at the backs legs, so that the ground will not be seen whilst she walks):

The node tree is then organised and laid out properly so that the different pipelines can be easily accessed, and clear to view if someone else wishes to make adjustments to the nuke script:

Shot five:

Shot five was not touched, as there are only twenty-two frames, and this shot is based on action, namely, the child entering from the back of the shot bumping into the child on the middle. More information from the director would be needed to ask for any changes.

Shot six:

For shot six, all the information from shot four has been used again, with the exception of the hold out mattes for the children against the other objects, which would be altered depending on how the children move in this shot:

  

Shot seven: 

Shot seven was similar to shot three in which this footage was shaky and needed a stabilisation. A transform node is used again to make sure the newly stabilised footage stays in frame:

Shot eight:

The last of the bluescreen shots is again similar to shot six, a duplicate of the original blue screen template from shot four, with the hold out mattes for the children altered to suit their new positions:

Shot nine:

The final shot in this sequence is of the dragons, the lamp and the children. This final shot is a repeat of the first shot, however this is done with one singular rotoscope, alongside stabilisation for the shot. One of the 'knobs' on the top of the lamp has been used as a tracking marker for the stabilisation:

Final node tree:

In conclusion, trackers have been used to stabilise the footage of many shots with shaky camera work, rotoscopes with their own keylights utilising inner and outer keylights allow the children, lamps, and dragons to be used against a blue screen, and there is a hold out matte for the children alone for the VFX artists to use for any extra effects for the children alone: