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  1. 3D & Motion Graphics
  2. Blender
Cgi

2 Points Tracking in Blender

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Difficulty:IntermediateLength:ShortLanguages:

1. Tracking the Footage

Step 1

Open Blender.

Open Blender
Open Blender

Step 2

Click on Editor and select Movie Clip Editor.

Movie Clip Editor
Movie Clip Editor

Step 3

It opens the Movie Clip Editor. Click on Open to import the footage in the movie clip editor.

Movie Clip Editor
Movie Clip Editor

Step 4

Go to the folder with the image sequence of the footage. Select the first frame and click on the Open Clip button.

Open Clip
Open Clip

Step 5

Now you can see the footage inside the movie clip editor window. Click on Prefetch Frames button to load the image sequence in the RAM. Alternatively, you can press P key.

Prefetch Frames
Prefetch Frames

Step 6

Since the footage has been shot by a hand held camera so you need to perform 2 points tracking. Try to search a good contrast point to track the footage. 

Once you have searched a point, press and hold Ctrl key and click with left mouse button onto that point. A tracker appears on the footage.

CtrlLMB
Ctrl+LMB

Step 7

Give this track point a name as Track Point 1.

Track Point 1
Track Point 1

Step 8

Now, click on Track Forward button to track the footage.

Track Forward
Track Forward

Step 9

Within a couple of seconds, the footage gets tracked. You can play the footage to check the reliability of the track. In my case, the footage has been tracked without any problem.

First tracking done
First tracking done

Step 10

Now search for the second good point to track the footage. The right corner of the wall is perfect for this. Press and hold Ctrl key and click with left mouse button onto that corner. A tracker appears on the right corner point.

CtrlLMB
Ctrl+LMB

Step 11

Rename this track point as Track Point 2.

Track Point 2
Track Point 2

Step 12

click on Track Forward button to track the footage. Even this time, the footage gets tracked perfectly. The tracking has been completed successfully.

Track Forward
Track Forward

2. Camera and Armature Setup

Step 1

Create empties from both tracks. Click on Tracking tab and select Reconstruction mode.

Reconstruction mode
Reconstruction mode

Step 2

Click on Link Empty to Track for both tracking points.

Link Empty to Track
Link Empty to Track

Step 3

Go to 3D View mode. You will see two empties in the viewport.

3D View
3D View

Step 4

With the box selected, press X key. Click on Delete to delete the box.

Click on Delete to delete the box
Click on Delete to delete the box

Step 5

With the Alt key pressed, press R and G keys one after another. The camera sets on the origin and looks to the center from the top view.

Alt-R and Alt-G keys
Alt-R and Alt-G keys

Step 6

Move the camera up a bit in Z direction.

Move the camera up a bit in Z direction
Move the camera up a bit in Z direction

Step 7

Press 0 key to look through the camera.

Press 0 key
Press 0 key

Step 8

Press N for the side bar. Check on Background Images. Click on Movie Clip and select the image sequence file.

Press N for the side bar
Press N for the side bar

Step 9

With the first empty selected, press Shift-A key. Go to Armature > Single Bone and create a single bone on the first empty.

Armature  Single Bone
Armature > Single Bone

Step 10

Press Tab to jump into Edit mode. Pick the tip of the bone and move it to the second empty.

Edit mode
Edit mode

Step 11

Press Tab key again to leave the Edit mode. Select the right empty. Press Shift-S key for the centered cursor. With the armature selected, press Shift-S again to snap it to the right empty.

Shift-S key
Shift-S key

Step 12

Parent the armature to the empties. First select the armature and then select the left empty. Press Ctrl-P key and select Object (Keep transform).

Object Keep transform
Object (Keep transform)

Step 13

Press Ctrl-Tab key to jump into Pose mode. First select the right empty and then select the armature. Press Ctrl-Shift-C to add a constraint. 

Select Stretch To constraint. Now the armature is connected to both empties.

Stretch To constraint
Stretch To constraint

3. Linking 

Step 1

Go to File > Import > Image sequence as planes.

File  Import  Image sequence as planes
File > Import > Image sequence as planes

Step 2

Choose the flag.tga file which is in a sequence and click on Import Images as Planes. I have made a flag animation in image sequence which I have to composite with the live footage.

Import Images as Planes
Import Images as Planes

Step 3

The image plane comes with the solid grey color. 

Image plane
Image plane

Step 4

To see the actual texture/ animation, enable Texture in the display menu.

 Enable texture
Enable texture

Step 5

To scale up the image, press S and scale the image plane.

Press S and scale the image plane
Press S and scale the image plane

Step 6

Attach the flag footage to the armature, so that the flag footage could follow the image. Select the flag footage and the armature respectively and then press Ctrl-P keys. Select Bone option.

Ctrl-P key
Ctrl-P key

Step 7

Play the footage and you will see the foreground image sequence of flag simulation going perfectly with the background footage.

Play the footage
Play the footage

The Finished Article

Conclusion

In this part of the tutorial series, I showed you how to create two-point tracking. In the next part of the tutorial, I will show how to perform four-points perspective tracking.

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