Having a plate image, a couple of reference pictures with the grey sphere, chroma sphere and macbeth chart it is important to match the exposure of the reference footage to the plate. Using Nuke, we first find an object which we will be referencing to. In our case it was a wooden box.
As the file is opened up in Nuke, we note down the average value of the colour in the chosen area taken from the plate. Then the exposure is adjusted for other reference plates the following way:
2) Create Exposure node in node graph
3) Change ‘Adjust in’ to ‘Stops’
4) Having a reference on values for Red, Blue and Green channels from plate increase the numbers
5) Add ‘Multiply (Math)’ node in the node graph
6) For each channel adjust the value accordingly to match to the earlier noted down values.
Once completing the procedure for other reference pictures, we can move onto creating a North, South domes alongside with any extra HDRIs for too bright lights sources (in this case the fluorescent light). First, it’s important to separate the Low and High Pass to see which sources are too bright. That is done by using the ‘Clamp’ node and Merge nodes with correct operation.
As the High Pass is created with the separation of overly bright sources (using ‘Merge (minus)’ node with A being the source and B being source with applied clamp), the fluorescent light is separated out with a use of garbage mask, it is then fed back into the Low pass with a use of ‘Merge (plus)’ node. This way (see below), the balanced light sources are included back. That image is then separated into North and South domes.
A similar procedure is done for the fluorescent light. It is also important to make a so-called ‘Sanity Check’ to make sure that none areas were affected or lost. It is done by merging the north, south domes and fluorescent light passes together and subtracting from the adjusted (in exposure) picture. If the result is black at most exposures other than extreme high numbers, then it’s all done and ready for render out to be put into Maya scene.
As the scene is now set up in Maya, it’s a good procedure to create separate groups for spheres, reference geometry, SkyDomes and Characters. This way we can easily maneuver the scene and hide/unhide the required groups. Firstly we create the sphere and apply correct textures on those. Then the skydomes are created, separate for each written out HDRI. Those are adjusted in orientation to match the reference plate pictures, which are also positioned in the scene so we can see then in render view.
The lighting can still be more adjusted, there are some problems such as warmer tones in the shadows, no reflection of characters in the shiny black surface on table, harsh shadows of those on the table, not enough bounce light.