Motion Tracking (Continued)

Second Test

This here is the second test of match-moving and placing CGI objects in a live action environment. Once again I used a video camera to record a hand-held shot of moving through a kitchen and into a back garden. The purpose of this of course was to further expand on the match-moving technique and being able to put CGI objects in a live action environment.

Above is the original footage clip that I used for this test.  

Once again, I imported the image sequence of the shot into MatchMover, set up automatic tracking for this particular shot and then exported the results to an exisitng Maya file that I created for the scene. No problems at all with this procedure, this part was successful.

I opened up the file in Maya and began to insert primitive shapes to test out the scene. Arranged a few cubes and cylinders to certain positions, making sure to check the view of the camera panel so that the objects can be seen. Then I rendered the whole scene and composited them together using After Effects.

First test of the match-moving procedure. As you might notice, the two cylinders near the top of the camera view are supposed to be within the kitchen but instead they remain ahead of us, making their existence in the environment unrealistic.

I attempted to fix that error by rearranging the cylinder objects in the Maya scene, moving them closer to the camera and within the area of markers shown in the image above.

Second test, which shows the changed positioning of the cylinders. As you can see, the camera moves towards and past them so they are blended in much better and it now seems as if they were actually in the kitchen.

Decided to expand on this scene by using more objects in the scene, setting them up within the main capacity of markers which of course is the layout of the kitchen, if you know what I mean. Also for more effect, I key-framed several of the cube objects to slowly rotate throughout the timeline. 

Camera perspective of the scene, showing the cubes positioned throughout so that the camera can move past them without colliding. Rendered the scene out again and composited the sequence with the original footage in After Effects.

 

Final version, giving the scene more of a three dimensional feel.

Third Test

This test here proved to be one of the most difficult match-moving tests I’ve done for this particular project. The footage clip I used for this, which of course is a quick shot in my back garden, had camera movements that were too hard for the automatic tracking mode in MatchMover to comprehend, trackers couldn’t focus on a certain point for too long due to quick movement and the result of camera blur.

Original footage clip of the shot. No audio.

I attempted to adjust the density and sensitivity modes in the automatic tracking settings and even slowed the footage down 400%, by time stretching the image sequence in After Effects, to try and make the trackers focus more effectively on the points but to no avail as again the trackers couldn’t remain in one point of the clip for long enough.

As you could see in the image above, not all trackers could be processed for the camera due to lack of information in certain frames, again due to the quick camera movement.

As mentioned before, I attempted to adjust the sensitivity and density of the tracker settings in order to achieve better results, unfortunately this was proved unsuccessful.

After trying all these methods, I realised I couldn’t rely on MatchMover for this particular shot and so I finally resorted to using the tracker controls in Adobe After Effects to use for the shot. By setting up three trackers in the image sequence of the clip, each one focusing on a certain point such as the tip of a roof of a house or a white football lying on the ground, I managed to achieve a simple effect. Of course even the tracker controls had a few problems with focusing on a point for too long due to the camera’s quick movement so I had to painstakingly and manually move the trackers in each key-frame to the same point of the object it should be focusing on. 

Of course, I had to move the tracker to the same position/point in each frame as in focusing on the football in the image above. It still got messed up slightly as I played the sequence as I noticed that the tracker suddenly jumped to another point in one frame and then to a different position in the next frame so I fixed that by deleting certain key points that were affecting the motion path of the tracker when it should be following the desired object.

After using three trackers focused on certain objects/points in the clip, I created three null objects in order to convert each key-frame of the trackers to said null objects so then I could assign the appropriate movie clip to each one. For this clip, I decided to use a glass ball that I made in an earlier After Effects project and an action essentials clip of a line of fire to blend in with the fence.

Final version with added effects assigned to null objects.

All these match-moving and motion tracking tests have in some way proven successful in the end and so I'm one step closer to achieving the desired effect for my final project. Still need to make a few minor adjustment to the techniques I'm using though but practice makes perfect.