Chapter 12: Matching Blender's Camera Movement to Live Action Footage

In this exciting chapter, we're going to focus on camera tracking in Blender. Camera tracking or match moving, as many call it in the film and visual effects (VFX) industry, is the process of matching the movement of a real-world camera with a virtual camera in your 3D software. One of the main reasons you would do camera tracking is to insert 3D objects such as characters, props, buildings, explosions, particles, or anything you can imagine into a live-action scene where a moving camera is being used.

This process is also used extensively with scenes that make use of a green screen, where the full background behind the actors needs to be replaced. Tracking markers are often placed on the floor or the green screen if no high-contrast objects are visible, which will make the tracking process much easier. Once you have a matching virtual camera, it is fairly easy to add 3D elements to your scene as the...

Creating an image sequence from a video

In this section, we will create a PNG image sequence from a video file using Blender. It's always good practice to use an image sequence rather than a video file when doing VFX work because using an image sequence will ensure that you are using the correct number of frames. An image sequence is also not linked to a Frames Per Second (FPS) value, eliminating possible issues. Many applications can convert a video file into an image sequence, such as DaVinci Resolve, Adobe Premiere, and After Effects, to name a few, but Blender can do it even better!

Let me show you how easy it is to convert a video into a PNG image sequence using Blender. Let's get started:

1. You can download the video I will be using from https://github.com/PacktPublishing/Taking-Blender-to-the-Next-Level/blob/main/Chapter12/Chapter%2012%20-%20Footage_5sec.mp4, but feel free to use your own footage:

Figure 12.1 – You can download...

Importing the image sequence into Blender

In this section, we will import the image sequence that we have created back into Blender. Let's get started:

1. Create a new Blender project.
2. Select all the default objects in the scene by pressing A, then X. Click Delete to confirm.
3. Click the + symbol at the top, to the right of the workspace tabs, and select VFX | Motion Tracking. This will open the Motion Tracking workspace:

Figure 12.10 – Opening the Motion Tracking workspace

4. At the top of the main viewport, you will see the Movie Clip editor. Click Open.
5. Browse to the folder where you exported the image sequence.
6. Press A to select all the images in the folder.
7. Click Open Clip to import the image sequence.

The image sequence will now be imported into Blender. You will see the video displayed in the main viewport. You can zoom in and out by scrolling the mouse wheel and pan around by holding the mouse wheel. You...

Camera tracking or match moving

In this section, we will begin the process of tracking the real-world camera by creating trackers on high-contrast features in the scene. We need to try and track features that are close to the camera as well as far away from the camera. This will provide parallax and will also help Blender create a better track.

If you have control over the filming of the footage, always try to use a high shutter speed as this will reduce the amount of motion blur in the footage. Motion blur is a camera tracker's worst nightmare. It is possible to track footage with lots of motion blur, but it requires a lot of manual input and will take much longer.

First, let's configure our scene and look at some of the tracking parameters. Let's get started:

1. Hover your mouse cursor over the main viewport and press N to bring up the side menu.
2. Click the Track tab.
3. Expand the Objects section.
4. Here, you will see the object that will be tracked...

Solving and refining the track and orienting the scene

In this section, we will solve our camera track using the trackers from the previous section to create a tracked camera in our scene. Then, we will refine the track by making some adjustments and deleting any problematic trackers. This is an important step to ensure that the camera track is as accurate as possible.

Tracking errors or bad trackers can cause 3D objects to slide and not stick to the track – this will break the illusion that the 3D objects are really in the scene. Finally, we will orient our tracked scene so that it aligns with our grid.

Let's get started:

1. Click the Solve tab to the right of the viewport to open the Solve settings:

Figure 12.43 – The Solve settings to the right of the viewport

2. Click the Solve Camera Motion button to solve our camera track.

You should now see the Solve Error value to the top right of the viewport. The lower this...

Testing the camera track with test objects

Once you are happy with the track, you can add test objects to your scene to test the camera track. This will ensure that any 3D objects that have been added to your scene will stick to the scene and be tracked with the moving camera. Let's get started:

1. First, let's hide the trackers from the 3D Viewport by clicking the Overlays drop-down menu at the top of the 3D Viewport.
2. Untick the box next to Motion Tracking to hide the trackers from the 3D Viewport.
3. Press Shift + A, then select Mesh and click Cone to add a cone object to our scene.
4. With the cone object selected, press G and then press Z and move the cone up so that its base is on the floor plane.
5. Duplicate the cone object a few times by pressing Shift + D. Then, move the copies around the scene. Ensure the bases of the cones are sitting on the floor plane.
6. Select the floor plane and press H to hide it from the 3D Viewport.
7. Now, press Spacebar...

Summary

Congratulations! You have successfully created a camera track in Blender. Camera tracking is one of the most powerful processes in the world of VFX. Once you have mastered the art of camera tracking, you will be able to add anything to your scene that you can imagine – think of Jurassic Park! As always, you need to practice this skill because every shot is different, and you will only get better with experience and lots of practice. Have fun creating amazing scenes!

In the next chapter, we will look at compositing. This is the process of making our 3D objects fit better into our real-world scene by adding shadows, lighting, and color grading effects. Please save your project now.