Join Lee Lanier for an in-depth discussion in this video Combining multiple elements of a 3D explosion, part of VFX Techniques: Compositing an Explosion with Fusion 7.
- View Offline
- So, we're back to the same network. I've added a blue underlay to highlight this area. We're ready to go back into 2D, and here's where we left off with that renderer of the 3D, the doors with the reflections. Now, let's create a new section. There's more to bring in. This time, we're gonna go back and bring in a 2D render of the explosion, itself, which was done in Maya with fluid dynamics. So, starting in this upper left area, we'll start with a loader and bring in the main blast, and this is in the 3DRenders folder, under Blast.
Take a look and here it is. It's the fire and smoke with the car cut out. Now, we're gonna go into Maya briefly and talk about that's done in a later video, but, for now, you can see that it's just a big explosion around the car. I do have to make sure it starts in the right frame, so, once again, I'm going to do a custom Hold First Frame, 19. There we go. Lets go to the next loader. We have two more parts to bring in. This time, it's a smaller blast.
It's little arms that shoot off on the sides, and the first one we'll bring in is called HoodBlast. It's a fire that shoots out of the hood. Take a look at this. There's a little trail that starts where the hood is and flies out. Now, this one seems too slow. The original blast, pretty good speed, that was set in Maya. In order to get this particular render to work, I had to slow down the simulation. It just feels too slow compared to the main blast, but we can time warp right here in Fusion.
So, to do that, I'm gonna go to a new tool. Add Tool. Under Miscellaneous, Time Speed. Time Speed is basically a time warper. I'll hook this blast to it. In the options, if i want the footage to be faster, I increase the speed over 1. If I want to slow it down, I lower it below 1. Now, when it goes faster, it throws frames away, and that's okay in this situation. If I was to slow it down, it'd have to blend frames together to create new frames, and it's not the best blend, but it's okay.
Now, if you wanted more advanced time warping, you'd have to get into the motion estimation tools, but we're not going to do that with this particular project. Since we are going faster, it's okay. I'm just gonna go and set this to 1.4 to speed it up, and let's play that back, now. Kinda looks a little bit better. Now, I do need to make sure it starts at the right frame, so once again, I'll do a delay. Now, it's not called Hold First Frame, here, it's called Delay. I'll enter 19, here.
What that means is it's not frozen anywhere. It simply doesn't exist until frame 19, so as long as I'm looking at the correct tool, here, there's nothing, nothing, nothing, nothing, nothing, and then, it starts, which is fine for an explosion. All right, one more loader. We have another companion explosion, or explosive arm coming out, and this one is called DoorBlast. It comes out of the doors. This one suffers from the same slowness, so I'm gonna add a Time Speed to that.
Now, I can actually just copy this one over. Control or Command C. Control or Command V. Hook this one up. Look at it. It has the correct delay, already, and the correct speed. All right, now I'm gonna combine these three different renders together into a master explosion. Once again, time for a merge. At first, I'll combine the hood and the door together, and they don't touch, so I don't really care about the order of connection.
It doesn't matter who's foreground or background. Now, they're together. Now, I need to connect that with the main blast. Here, I do care about the order. I want the main blast to be in the background, and the other merge to go into the foreground. Lemme make sure that hooks up. There we go. And this merge into the foreground. Gonna look at that, and that's everything. Now, there's some issues with color grading.
We're gonna get to that later, but for now, I can improve this slightly and better blend the small explosive arms with the main blast by changing the blending mode. Much like other programs, these merge tools have a blending mode, which is right here, and you can change that from Normal to something specialized to make the blend better. In this case, Screen works great. Screen throws away the dark parts, so basically, it puts the bright parts over the background and throws away the parts that were darker. So, I'm gonna lose those dark fringes, and it starts to merge a little bit better with the main blast.
Let's take a look. There we go. There was our explosion. So, we used three more loaders to bring in some more 3D renders, and we're able to warp the speed of two of those through Time Speed, and then, once again, combine them with a couple of merges.
- Setting up a Fusion project
- Importing plates, static art, and 3D renders
- Merging nodes
- Assigning materials
- Color grading the explosion
- Working with fluid dynamics in Maya
- Combining the renders and 3D with live-action footage
- Creating post camera movement
- Rendering out the final effect