We dedicated this lecture to asked all the questions we had about what we have seen in this term and our weekly homework and projects.
Hero shot green screen removal homework correction
In this comp I had an issue getting the finer details of the girls hair when removing the green screen and comping with the forest background. Also, the snowflakes I keyed to add in the foreground of the scene were barely visible. In order to take the hair details, I had to take a ‘IBK colour’ node and pick the darks and lights of G (green colour) so it selects as much detail of the hair as possible. I can also use ‘Filter erode’ to remove noise and then add ‘patch black’ (like at 20) to remove black part. Then, I can add a ‘IBK gizmo’ set to green, and then link ‘fg’ to green screen plate, and ‘bg’ to background plate (so it takes background features). Then, I can tick ‘use bkg luminance’ in the ‘IBK gizmo’ node, so it takes the background luminance, and tick ‘use bkg chroma’ so it takes background colour too. I can then ‘Merge (over)’ the ‘A’ link to the ‘IBK gizmo’, and ‘B’ link to background. This will take all the details of the hair from the green screen and add it to the luminance of the new background.
Regarding the snow problem, I was taking the luminance with ‘Keyer’ node from the original plate, and I had to connect it to the ‘Transform’ node instead so it takes the correct aspect ratio. Then, every time I ‘Premult’, I always need to use ‘Merge (over)’, so I changed to this node. I can also add more or less effect with ‘Multiply’ node.
Markers clean-up homework correction
I asked the professor for the distortion I was getting from the smart vector and he confirmed to me that the problem was that the node was affecting the whole image. So in order to correct it, I had to add a ‘Premult’ to the ‘Roto paint’ and add a ‘Framehold’ again (before the ‘ST map’), so the distort only affects the alpha created with the ‘Roto’. Also, I need to improve ‘Roto paint’ using the techniques to control light changes.
Garage comp homework correction
In this comp I had the issue with the shadow being cast on the wall hole. To remove the shadow from the wall hole, I need to take the previous roto made for that wall and ‘Merge (stencil)’ in the shadow part (between ‘Blur’ and ‘Grade’ nodes). Then, before this ‘Merge (stencil)’ node, we add an ‘Invert’ node so the roto alpha only takes the hole instead of the wall. To correct some bits that are outside this previous roto and that now are showing as this has been inverted, we make a quick ‘Roto’ that selects the area we want to keep (the hole in this case), we adjust the position of this ‘Roto’ in several frames, and then we ‘Merge (mask)’ to ‘Invert’ node (‘B’ connection). Lastly, we make the edge of the roto less crisp adding ‘Edge blur’ so it softens it.
I also fixed the back objects as they were looking too dark and the smoke effect was not affecting them so it did not look realistic. I then desaturated the colours adjusting their ‘Grade’ nodes and then added a ‘Merge (over)’ from the smoke card block to these objects.