In last week’s tutorial I talked about how to create convincing looking muzzle flash (gun fire) effects. This week I decided to cover the second half of the equation and talk about how to make your bullet hit effects looks awesome
I hope you enjoy this tutorial
The Preparation – The Overlay Layer
One of the most frustrating things about creating visual effects for bullet hits is to ensure all the blood/debris/sparks appear behind your actors or objects in the scene. Imagine masking them out frame by frame and then you decide to move them or replace them with different footage. You end up having to go through the whole frame by frame masking nightmare again
To avoid this, I have decided to go another way and it has worked out pretty well so far
Instead of masking out the elements to sit behind my actors or objects, I rotoscope out the actors or objects and create an overlay layer. I then place all blood/spark/debris effects on top of my base footage layer without masking and then place the overlay layer on top of that. Instantly, all bullet hit effects appear to be sitting behind the elements in the overlay layer
And the best thing about this solution: it’s flexible! I can move or replace all bullet hit elements without any extra work required.
Starting with the base footage, we first rotoscope out our actor for the duration of the bullet hit to create the overlay layer. In After Effects CS5 and up, I highly recommend using the rotobrush tool to help you with this task as it can be a little tedious. The rotobrush tool is not perfect, but it does make your job a lot easier
Be sure to enable the ‘refine matte’ option on the rotobrush effect, it will make the edges of your overlay look cleaner.
Because the rotobrush effect is really slow to render, we render out our overlay layer. To maintain the transparency of the video, I usually export as AVI and set the output channels to RGB+Alpha.
Once we’ve done that, we can reimport the clip into your scene and place it on top of your base footage. Don’t forget to disable the rotobrush effect on your base footage as we no longer need it. I usually don’t like to delete it just in case I need to make adjustments and re-export the overlay
The Bullet Hit
Now that we have the overlay layer created, we can add some blood splatters for the bullet hit onto the wall behind the actor. Simply take a blood splatter elment and place it above the base footage but under the overlay layer. Without any extra work the blood appears to be sitting behind our actor
Next, take an image of a bullet hole or a damaged plaster wall and place it over the blood effect layer. Scale it and position it right over the centre of the blood. You may have to add a curves adjustment to ensure the lighting is correct and the bullet hole fits into the scene. Again, notice that no masking is required.
One important thing for the bullet hit is the blood mist cloud. When a bullet hits a person, the impact usually creates a small explosive cloud of blood mist due to the force of the impact. To simulate this effect, we add a smoke or dust element on top of the overlay layer. We then colour the layer red.
In After Effects, you can do this by applying the Colorama effect. Leave the input as ‘Intensity’ and select ‘Red Ramp’ for the output. If your effect appears to be almost solid red, it is because Colorama is overwriting the alpha channel. To fix this, expand the ‘Modify’ tab and untick the ‘Modify Alpha’ checkbox.
I usually like to make the blood a bit darker so it looks a bit more realistic, but feel free to tweak it as you like. Make sure the blood mist cloud shoots out at the moment of bullet impact and fades out after about 1-2 seconds.
Lastly, we can add some debris from the wall to complete the bullet hit. If a bullet was to pierce the shoulder of our actor and hit the wall behind, it would likely cause some plaster fragments to fly around. You can either create a particle effect for this or simply use some wall debris stock footage
I prefer to opt for the latter if possible simply because it saves time and with a bit of curves adjustment you can make it sit nicely in the scene!
Since the bullet hit is a very fast effect and some of the fragments would fly over our actor, I prefer to place the fragments on top of the scene.
Finally, you can add some curves and saturation effects to the bullet his scene a nice ‘film look’
Note that the layers you need for a great looking bullet hit effect will depend on what (or who) your bullets are colliding with. But I higly recommend using an overlay layer as outlined above – it will save you a hell of a lot of time, render faster and allow you to experiment around more easily until you are satisfied with your bullet hit
Realistic Looking Gun Muzzle Flashes in 6 Easy Steps
March 4th, 2012
I see way too many badly done muzzle flash effects on YouTube to not want to do this basic Visual Effects 101 tutorial.
It is really not hard to add a few layers onto your scene to create great looking gun fire. And this video will show you how
Compositing the layers for a realistic muzzle flash
To create this effect, you will have to composite a number of layers. Of course, these are not hard set rules so experiment if something doesn’t seem to fit right – to me, that is always the most fun part anyways
The first thing I add is the actual muzzle flash effect. I really love the Action Esssentials 2 package from VideoCopilot and for $99 for the 720p version, I highly recommend it. It’s filled with pre keyed stock footage and I use it almost daily. However, you can also find free action stock footage just by searching on google
Here’s a useful link to free stock footage from detonation films.
Anyways, take and position a muzzle flash element on top of your base footage.
Next, add another solid colour layer to simulate the light emitting from the muzzle flash. Set it to a colour that is very similar to the muzzle flash and change the blend mode to additive. I usually set the opacity to around 20.
Just putting a solid layer over everything does look pretty crappy. If there was a real muzzle flash in the scene, only the elements facing the front of the gun would be lit. We can simulate this by applying some masks and cutting out only the areas that would directly be hit by the light.
Once you’re done, your shot should look something like this:
It’s not bad, but I personally find that using a simple overlay layer to simulate the muzzle flash light sits very unnaturally on top of our footage rather than in the scene. We can make this look a lot more natural with a technique I described in my After Effects – Natural Lighting VFX Using Mattes tutorial: by creating a matte layer.
You can do this in most compositing software packages, but I will talk here in terms of After Effects to keep things simple.
Duplicate the base footage layer and drag it above the light layer. Add a saturation effect and bring the saturation down to 0 so you end up with black and white footage. Then, add a brightness/contrast adjustment and increase the contrast. The idea is that the bright areas of this matte layer will essentially define the opacity of our light layer. Where the matte is brighter, the light layer will be more opaque, where the matte is darker, the light layer is more transparent.
Finally, add a blur effect to soften the matte a little bit.
Now go to the ‘track matte’ option for your light layer and set it to ‘luma’. This tells After Effects that the opacity for this layer is defined by the brightness of the layer directly above, which is our matte layer. And voila, the light from the muzzle flash sits a lot more natural in the scene.
I know, I know, it’s not ‘realistic’, but the whole point of the matte is simply to glue the light and the footage together and make the light be dependent on what’s in the scene. By doing this, you tie the layers together and it won’t look like you simply stuck one layer on top of the other
Finally, you can add some curves adjustments to the entire footage, colorise it, filter it, whatever you like to give your muzzle flash shot that nice ‘film look’
Following these 6 simple steps will usually result in great looking muzzle flash effects, but sometimes the situation might call for something different. Never, ever be afraid to deviate from the ‘fixed rules’ and experiment
Progressive vs Interlaced And Why Your Video May Appear Distorted
February 12th, 2012
When it comes to LCD screens, video cameras and DSLRs, everyone would have come across the most common terms for video modes like 1080p, 1080i, 720p, 720i, etc… but many people don’t actually know what the ‘p’ and the ‘i’ stand for.
They stand for pregressive and interlaced respectively.
Another important thing that, as a film maker, you should know is pixel aspect ratio. Sometimes when you export your video, it may appear stretched or squashed because your pixel aspect ratio is incorrect.
Hopefully this week’s video will be able to clarify these things
Progressive vs Interlaced Video Mode
All film consists of a sequence of images that is (usually) played back at at least 24 frames per second. In digital video, each frame is a grid of pixels and with each new frame, the pixels on your display are updated with new colour values. However, depending on what video mode you are using, not all pixels may be updated with each new frame.
This is where progressive and interlaced video differ.
In progressive video, all pixels on your screen are updated with each new frame. This ensures smooth animation, but requires more data to be stored (and thus bigger file sizes) for each frame of video.
In interlaced video, each frame only updated every other row of pixels, alternating between the odd and the even rows. This means that it takes 2 frames for all pixels on your screen to be updated and, because less data needs to be saved for every frame, leads to smaller file sizes.
However, it does lead to very ugly video artefacts, especially around the border of moving objects
If an object is moving through the frame very fast, it will be at very different positions in consecutive frames. However, because interlaced video only stores every other row of pixels, when played back, strong horizontal lines can be seen where the object has moved.
I highly recommend to avoid interlaced video wherever possible. It is not always easy to de-interlace your video and it will save you a lot of headache to ensure your camera/display supports progressive video
Pixel Aspect Ratio
On your computer screen, all pixels are square. However, when it comes to video cameras, film and broadcasting standards, not all pixels are created equal. Sometimes pixels are more wide than they are tall. The relationship between the width and the height of the pixel is referred to as the pixel aspect ratio
Why should you care about pixel aspect ratio?
If you are a film maker or have recorded some video with a DSLR camera or a camcorder you may have encountered the problem of you video appearing stretched or squashed when you load it into your post production software or display it on a tv screen.
The most common reason for video to appear stretched or squashed is that the pixel aspect ratio used during displaying the video does not match the pixel aspect ratio that was used to record the video.
Assume you have a video recorded with a pixel aspect ratio of 1.333 (many camcorders record at 1440×1080 with a pixel aspect ratio of 1.333).
Your video comes out of the camera like this:
Now if you display this video on a display or in your post production software using a square pixel aspect ratio (1), then the video will appear squashed:
Conversely, if you recorded a video at a square pixel aspect ratio, your video would come out of your camera like this:
If you displayed this video using a pixel aspect ratio of 1.333, the footage would actually appear stretched.
If your video appears stretched or squashed, check that your pixel aspect ratio setting matches the pixel aspect ratio of the camera you used to record your footage
It is almost Valentine’s Day and, well, what is more romantic than a bunch of trash bins proclaiming their eternal love for the garbage man in a song?
Happy Valentine’s Day!
There were two parts to creating this Valentine’s Day music video:
Composing the barber shop style love song
Filming and syncing the trash bin lids to the voices
Composing the Valentine’s Day love song
I have never tried to compose an a-capella piece, but once I had the melody line and the chords down it was actually not too difficult
I ended up having the bass and the baritone (leftmost 2 trash bins) sing over the base notes from the chords while only the tenor carried the melody notes.
To add a bit of variation and make it sound a little more interesting, the bass and baritone only follow the main vocals half the verse and then break out into longer, more background style vocals. This also helps make the chorus line stand out cleanly against them
During the chorus I added a choir group containing a bass, a tenor and one soprano voice (sung I head voice).
I have to admit that I ended up using a fair bit of auto tune as I’m not a terribly great singer and the tenor voice of Willis is pitch shifted up by 4 semitones because I could not sing high enough But I am pretty happy with the results and the feel of this Valentine’s Day song.
Shooting and syncing the trash bins
Once I had the music for the Valentine’s Day song, I had to combine it with the footage.
I attached a fishing line to each of the bins separately and filmed the lid moving up and down once. In post production I had to edit out some of the parts whe the fishing line, because it was sometimes clearly visible in the direct sunlight.
The stage of synchronizing the lid movements with the audio is probably where I spent the most time.
I placed the footage in After Effects, duplicated the trash bins with the cloning effect and enabled time remapping on them. With the music added, I then matched up the opening of the lids with the volume of the individual voices. For this, I used a little trick.
I used Motion Sketch to record my mouse movement on a Null object and linked the time positon of the trash bin to the x coordinate of the Null. When the Null was on the left side of the screen, the lid would be closed, if it was on the right side of the screen, the lid would be fully opened. I then played back the track and, with my mouse, recorded the lid movement to match up with the audio.
I repeated this for all trash bins
Finally, I added some colorisation and a little bit of story around the Valentine’s Day love song to wrap it all a little better
I love using my green screen for visual effects. If used properly, it allows for a vast number of cool effects to be created with relative ease However, if you are not careful during filming you could end up with a number of problems in post production that will hinder if not completely block the visual effect you had in mind.
To not let all my failed attempts go to waste, I decided to create a video tutorial on the most common green mistakes and how you can avoid them!
Here is a quick summary of the 5 most common green screen mistakes and some tips on how to avoid or fix them
1. Shadows on the Green Screen
The Problem
If your subject is too close to the green screen or the light from the front is too strong, a dark shadow might be cast onto your green screen.
This can cause unpleasant artefacts when you finally try to apply the chroma key. Because the dark areas on the green screen are too close in colour to the dark areas of your subject it may be hard to key them out cleanly.
On the right side it’s hard to tell where the arm ends and the shadow on the green scren begins.
The Solution
Position your subject a little bit at a distance to the green screen to reduce the shadows.
Try to avoid a single hard light on your subject which will cause strong shadows.
Add lights behind your subject that are aimed at the green screen to brighten up the dark areas.
2. Unevenly lit Green Screen
The Problem
This problem is very similar to the previous one. While the green screen is now better lit, the lighting is very uneven, creating dark and bright areas in the background.
Again, this can make the application of the chroma key difficult without clipping away parts of your subject. Here is an image of what the unmodified screen matte looks like.
The Solution
Sometimes you can rectify the solution in post by carefully controlling the ‘deposit black’ and ‘deposit white’ parameters in your Keylight Effect (if in After Effects). Other compositing software chroma key effects will have similar options, so try this first
To prevent getting into this situation to begin wtih, try to add lights aimed at your green screen to even out the lighting before you shoot.
3. Motion blur in front of Green Screen
The Problem
If you shoot at a slow shutter angle, you may end up with motion blur in front of the green screen.
This is something that is really hard to fix in post production since the areas where the motion blur occurred will be blended together with the green screen. It can be hard or even impossible to set up a clean chroma key without losing parts of your subject.
The Solution
Try to have your subject move slowly to avoid motion blur to begin with.
If you need fast movement, use a higher shutter speed (a smaller shutter angle) to avoid motion blur. Because this will impose a certain hypersensitive onto your footage, you can add the motion blur back in post production – AFTER you applied the green screen
4. Clipping out of the Green Screen
The Problem
You shot in front of your green screen and the subject was out of the screen for just a short moment. Not a problem, right? Fix it in post?
This can be very annoying to fix as you will have to manually rotoscope out all the elements that left the green screen.
The Solution
While the rotobrush tool in After Effects may help make the job easier, I strongly recommend reshooting the footage if you can
5. No backlight
The Problem
This is not really a problem, more a tip on how to make your subject stand out a little cleaner against the green screen. This will make application of the chroma key a lot easier and it will help give the actor or object a bit more shape by lighting them smartly
If you just shoot your subject against a green screen with light from the front, the outline of the subject is not very well defined.
The Solution
Add a light between the green screen and your subject but aim it towards the camera at the back of your subject. This will create a nice highlight outline around your subject and give it shape and make it stand out nicely against the background
I hope these tips will be helpful when you’re doing your next green screen shoot! I certainly learnt them the hard way hehe
