Even if you are not Michael Bay, you will certainly have thought at least once of detonating something in your movies. In these pages we show you how with Kdenlive and GIMP it is possible to obtain this effect at a cost almost equal to zero.
Until a few decades ago, the easiest way to insert an object’s explosion into a film was to actually detonate it, and to hope that nobody got hurt. Remember the scene of the Langstone bridge explosion in the movie “The Good, the Bad and the Ugly”? If you have looked at it well, you will have noticed that one of the stones of the bridge flies, during the explosion, less than a meter from Clint Eastwood’s head: the scene is spectacular, but the “good guy” risked being hit by a splinter at least 2 kilograms and end his career prematurely. Fortunately, the actors (and also the directors) are no longer the 1960s, and today it is possible to simulate very realistic explosions in computer graphics. As absurd as it may seem, an explosion produced by computer programs is often more realistic than a real explosion. After all, some fiction has always been introduced even in the early years of cinema, as far as explosions are concerned. In fact, in reality almost no explosion produces the masses of fire that we are used to seeing on the big screen: it would be a waste of energy. The explosives used in reality to demolish objects mainly produce transparent, and therefore invisible, gases and at most a small amount of smoke. Thanks to the magic of computer graphics, it is now possible to have videos of “beautiful” explosions that can then be superimposed on any other object to pretend that it is exploding. And Kdenlive, with its composition tool, is perfect for this task. Not only that: Kdenlive can also allow us to deform an object in order to give the illusion that it is swelling before exploding from the inside. The trick is simple: first of all we isolate a frame where the object appears immediately before the moment we decided to detonate it. Then, using the GIMP image editor, we eliminate the background in order to isolate the object in question. At this point just insert the image containing only the object in Kdenlive and superimpose it on the original movie, applying distortion. Probably, the probably greatest difficulty will be finding good explosion videos to insert in our video. The videos we use for our tutorial can be found on the detfilmshd.com website. Movies must be purchased, but it’s worth it as they are ready for use. Of course, we recommend that you use the “pre-keyed” version, that is, those whose background is already transparent, so you don’t have to apply the chroma key. If you don’t want to spend, you can get some low definition movies, which could still be good for some movies, on the old site, now closed but still accessible through the Web Archive: http://web.archive.org/web/20130508224023/http://www.detonationfilms.com/ Stock_Directory.html . T ruined an explosion of our liking, just insert it in Kdenlive, above the original movie, but below the image of the object that “swells”. In this way the public will have the illusion that the smoke and flames of the explosion come from inside the object that is exploding. As always, you can see the example video at the following address: https://www.youtube.com/watch?v=qyiidigXiYg
Sound also matters
In explosions, sound effects are important: although we intend to make our movie with a soundtrack, we cannot avoid the sound of an explosion at the right time. An explosion without its sound effect is not realistic. Of course, we can get a good realistic effect by looking for some videos on YouTube that contain sounds of explosions, such as the films of the LUCE archive on the first and second world wars. Alternatively, we can produce the sound we want ourselves by recording, for example the sound of an exploding balloon, or by lighting a firecracker inside a bucket. Of course, it is also possible to add particular effects in post production: for example, the explosion of a balloon is a very rapid sound, it ends in less than a second. If we want to prolong the sound effect we can add an echo directly from Kdenlive, or change the speed or time of the sound recorded with the Audacity program.
We choose the clips
We select the right clips and place the first one in the timeline
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap1.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap2.png)
Help from GIMP
We modify the image of the object that explodes with GIMP
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap3.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap4.png)
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![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap6.png)
Deformation before the explosion
With Kdenlive we can deform the image by “inflating” the object that is to explode
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap7.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap8.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap9.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap10.png)
Choose the right times
For a good effect, the timing must be corrected on the frame
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap11.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap12.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap13.png)
![](https://kdenlivetutorials.com/wp-content/uploads/all/small_vfx18_snap14.png)