How DNEG crafted the alien environment seen at the start of ‘Sonic the Hedgehog 2’.
The opening scenes of Jeff Fowler’s Sonic the Hedgehog 2 see the evil Dr. Robotnik (Jim Carrey) still banished on a mushroom planet. Crafting that world was the responsibility of DNEG and visual effects supervisor Kunal Ghosh Dastider, who worked with overall VFX supervisor Ged Wright on the film. Ghosh Dastider breaks down the digital environments in this interview with befores & afters.
b&a: What did they end up shooting Jim Carey on for this? Was it basically just bluescreen or some sort of partial set?
Kunal Ghosh Dastider: They had a partial set which was more or less where Robotnik was doing his action–he was surrounded with the first row of mushrooms. And then we took over from that, everything behind that we extended. There are some shots where we did the whole thing in full CG also, where we are pulling out for wider shots. It’s always good to have something real when you shoot and then you can extend.
b&a: What kind of combination of 3D environment and DMP is there?
Kunal Ghosh Dastider: The challenge was to give it a structure, a visual structure that the eye can follow and that’s not overpowered. We could just scatter mushrooms in Houdini, big, small. That would be the easy solution, but it would just be overwhelming for the eye. Jeff wanted to make sure that you could read these things, that there would be a visual harmony across the shots.
So we started working in layers–we built a big structure of the rocks, of the terrain. And then we started to hand place or manually place the big mushrooms. Then the smaller we went, we started to scatter things around those big mushrooms. We added some stones and little rocks and ferns and moss here and there.
The smaller we went, the more procedural we went. But the bigger stuff, just to give that visual guidance, was all manually placed. And that was a challenge. We would do the environment through a camera, and then we would start to populate the environment with all the cameras in the sequence, just to look through and see that we had enough. Sometimes it was too much so we had to balance it out, so that it worked across all the shots.
b&a: Did the mushrooms themselves present any particular challenges for rendering?
Kunal Ghosh Dastider: There’s always render challenges somehow, especially when you have so many mushrooms. The sub-surface scattering was not that crazy. if you put a spotlight behind a little mushroom, it just blows out and you see all this scattering happening. But with 30 feet tall mushrooms, if you have that much scattering, it also breaks the scale. So we have it slightly on the edges, sometimes, depending on the thickness, but they were actually pretty solid.
We got away with a lot of that sub-surface scattering. We also gave the night shots that we added a bioluminescent look, although that was more like a texture-based cheat to make that work.
b&a: Is there any other particular part of that sequence you wanted to mention?
Kunal Ghosh Dastider: Apart from this large scale environment that we had to make, there was also the energy blast when he uses the quill, which causes a shockwave, making the mushrooms bend over. That was a very particular effects-heavy ‘kaboom’ that we had to do. That was fun, because for us, it was not a super effects-heavy show. So it’s always fun to blow up some stuff here and there.