Explosions are impractical effects for small movie makers and hobbyists like me who need to learn critical VFX skills. I can’t just go someplace a “blow something up” because just writing that on my blog is going to get me on a watch list, never mind actually doing it and getting a visit from the Feds. That’s why we have visual effects: for all those times we want something to look real, when in fact we were just sitting in our basement in our PJs playing with video clips.

Explosions themselves are usually elements that cannot be created by hand — or shouldn’t be created by anything less than the professional hand. Trapcode Particular has a few very nice explosions and fire effects, but for the maximum realism, we have to turn to high definition video clips. Several companies out there have taken the time to blow things up and record the results, and by performing this against a solid black background, we are able to use these clips and isolate the explosion with necessary transparency in our video.

Knowing that I wanted to apply this effect, I took some (ill-composed) video on my walk around the business park yesterday. I was looking for a building that had some decent, isolated windows which is a task that’s more difficult than you think. Most buildings around me are essentially complete walls of glass, and using one of those I’d have to really worry about rendering shock wave effects and secondary explosions down the line.

Naturally there’s a lot wrong with this video. First, I wanted to add a camera shake, but I painted myself into a corner and couldn’t do it the way I knew how in the time I had to do it, so I didn’t. Also, no sound. Third, although I changed up some of the coloration using an adjustment layer, I’m not satisfied with the way the fire looks against the rest of the video. Finally, because I used what explosions and fire video I could find legit for free, none of it is really optimized for Maximum Realism(tm), and I had to do as best I could with what I had with the skills I have.

Relevant Websites

I had to find some explosions. I have a few packs of free explosions from various locations, but none of them could be oriented to “blow outward”. I ended up on ProductionCrate.com last night, which offers some free assets among their pro-subscription offerings. Considering their yearly membership fee is (currently) $50/year, I signed up this morning for full access to their library. I wish I’d looked harder at this eariler as I could have gotten some better assets.

Relevant Resources

I have three fire videos from ProductionCrate, and one Particular generated smoke cloud. Also, I shot the video on my Osmo Pocket at 4k/25.

Technical Details

At it’s most basic, there’s two layers of explosion videos precomposed, scaled, and rotated into place. I had to mask out some areas of the window because the explosion was a bit overzealous, and needed to be constrained to the window area.

Beneath that went the Particular smoke. I was having some issues with Particular last night, as my PC was struggling to render. I had tried to use Particular to add exploding glass particles, but AE crashed three times trying to add this effect, so I skipped it.

There’s a solid layer between the building and the flames which is of the same color as the orange part of the explosion, masked, and feathered. This mask is keyframed around the times when the explosion enters and exists, to give a quick coloration to the building as the explosion emerges through the window.

The footage was camera-tracked, because I needed a null to serve as the anchor for the last bit of lintel flames on the window since the footage moved on occasion.

Finally, I added a bit of grain to the video (for that RealCinema(tm) feel!), and tried my hand at colorization using Lumetri color on an adjustment layer. While I like the overall results of the video itself (winter around here does take on that sickly blue tint, although the video was shot on an OK weather day), the explosions still look a bit “pasted on”.

Going forward, I might try and recompose this using proper assets now that I have access to better materials. I might also try and set up the effect so I can add proper camera shake to the scene. I want to get the exploding glass set up, so I might actually generate that and export as a separate movie (or see if ProductionCrate has samples). Finally, I want to look into making the coloration better, so the explosion looks more natural in the environment. I also think I need some post-explosion flames and darker smoke lingering after the fact.


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