I came to Ar Y Tracs 2 rather late in production to support the other compositor Rodrigo while he worked on the large number of train and crowd replacement shots for the end of the special. My task was to complete a number of the more cosmetic VFX such as monitor burn-ins, adding reflections, adding smoke, expanding a golf course landscape and a couple of greenscreen shots of characters on top of a train carriage, something that couldn't be achieved practically.
The two reflection shots were fairly straightforward. The first was of one of the characters staring out at the landscape as he makes his way to the rugby game, actually filmed in a station. The reflection had been shot from the window of a real train using a Canon 5D so I simply reversed it and warped it to match the angle of perspective. I used the landscape element to also drive interactive shadows and a very blurry reflection on the metal of the train carriage. The other reflection shot had also been filmed in a station, although the element of the golf buggy was too low and required the addition of more grass and a sky above it. This one does look very flat, but that's mainly because the two angles don't match. If this were a higher budget feature, I would have just done the buggy CG.
There were various TV burn-in shots that I shared with Rodrigo. Mine were of a recording of a rugby match and then a wildlife programme. Burn-ins are difficult because simply putting a green or blue image on the screen (as it was in this case) often causes a problem of fringing because the light from the TV is greater than the light on the actors themselves. Therefore, it bleeds through transparent elements like hair and clothes and means you have to do a more aggressive key than normal. Conversely, a black screen would give you the added benefit of the reflection but require rotoscoping, particularly if the character has dark hair (as would have been in this case). It's a tricky thing to get right and, based on this experience, I think I might use the black screen next time to see whether it produces a better effect. It depends on the camera and how much noise is created by the sensor.
The final two shots in these examples are of the train roof. In the shot of the character looking down through the hatch, I just needed to key him from the very clean greenscreen and add a new sky. Since I was also doing the exterior shots from this sequence, I was able to reuse the same sky to make sure it matched. Additional depth of field was added to reduce the distraction of the other character visible in the bottom right. The hardest part was keying around the sharpening artifacts created by the detail settings on the camera, something that plagued us on Grandpa in my Pocket: Series 1. In-camera sharpening is completely unnecessary for HD and the bane of my life.
The wide shot of the characters on the train roof was shot completely on green in a car park (of course) to get the ambient sunlight required to match the location. Again, this was a fairly simple key and I also managed to get their shadows from the curved piece they were sitting on. The black levels were the most important thing to match here and I applied a very subtle light wrap. I find light wrap tends to be overused for greenscreen and is not usually very visible on real sky/land join except in bright sunlight. On overcast days, there's hardly anything at all. Funnily enough, a month after this was shot, I ended up filming a children's series at this same warehouse with the same equipment and with the same Grip visible on the left. Small world.
The two reflection shots were fairly straightforward. The first was of one of the characters staring out at the landscape as he makes his way to the rugby game, actually filmed in a station. The reflection had been shot from the window of a real train using a Canon 5D so I simply reversed it and warped it to match the angle of perspective. I used the landscape element to also drive interactive shadows and a very blurry reflection on the metal of the train carriage. The other reflection shot had also been filmed in a station, although the element of the golf buggy was too low and required the addition of more grass and a sky above it. This one does look very flat, but that's mainly because the two angles don't match. If this were a higher budget feature, I would have just done the buggy CG.
There were various TV burn-in shots that I shared with Rodrigo. Mine were of a recording of a rugby match and then a wildlife programme. Burn-ins are difficult because simply putting a green or blue image on the screen (as it was in this case) often causes a problem of fringing because the light from the TV is greater than the light on the actors themselves. Therefore, it bleeds through transparent elements like hair and clothes and means you have to do a more aggressive key than normal. Conversely, a black screen would give you the added benefit of the reflection but require rotoscoping, particularly if the character has dark hair (as would have been in this case). It's a tricky thing to get right and, based on this experience, I think I might use the black screen next time to see whether it produces a better effect. It depends on the camera and how much noise is created by the sensor.
The final two shots in these examples are of the train roof. In the shot of the character looking down through the hatch, I just needed to key him from the very clean greenscreen and add a new sky. Since I was also doing the exterior shots from this sequence, I was able to reuse the same sky to make sure it matched. Additional depth of field was added to reduce the distraction of the other character visible in the bottom right. The hardest part was keying around the sharpening artifacts created by the detail settings on the camera, something that plagued us on Grandpa in my Pocket: Series 1. In-camera sharpening is completely unnecessary for HD and the bane of my life.
The wide shot of the characters on the train roof was shot completely on green in a car park (of course) to get the ambient sunlight required to match the location. Again, this was a fairly simple key and I also managed to get their shadows from the curved piece they were sitting on. The black levels were the most important thing to match here and I applied a very subtle light wrap. I find light wrap tends to be overused for greenscreen and is not usually very visible on real sky/land join except in bright sunlight. On overcast days, there's hardly anything at all. Funnily enough, a month after this was shot, I ended up filming a children's series at this same warehouse with the same equipment and with the same Grip visible on the left. Small world.