Tips for collecting footage:
- When filming the video you want to track, make sure you have high contrast points that the software can track – for example, a post you write on a table or colored tiles on a floor. You need to know the distance between these two.
- Plain white walls are not good because there are no contrasting dots for the software. Tiles are good as corners where the connection makes good track points, and the grid shape is useful for aligning your coordinate system. Carpets with busy patterns can be a problem because they have too many similar patterns that the software can confuse.
- If you place an object, such as a post note, you will need to remove it later. This can be done by adding a layer with the texture of its surface in your 3ds Max scene to cover the area of raw material.
- Well lit areas can be difficult because color tones fade, making the track points difficult to track.
- Hold your camera still during filming. It will make it easier for the software to analyze frames.
- Some shots just don’t track well and need to be re-recorded.
Automatic tracking in Matchmover.
- Matchmover can either track material automatically or you can do it automatically – this is easier, but can take a little longer depending on the material.
- Matchmover does not accept certain file types directly, so send the material to After Effects or Premiere first, insert it into a new compositing and output it as a .png sequence. Don’t choose compression in the render settings – they should be as knacking as possible.
- In Matchmover, go to File > Load Sequence and select the first of your .png recordings you just made from After Effects.
- Press f10 to open the Automatic 2D Tracking window. Normally hold the slider in the middle so that there are not too many track points Max can edit. Of course, your hardware will determine what the software can process, so remember.
It may take a few minutes, but you should see small crosses with green tails appearing everywhere on their material as it is tracked.
Set up a coordinate system.
At the moment all track points correlate with a 3D scene, but that scene has no scale or orientation. If we imported it this way, a chair could look upside down and a mile long. We can sort that out in Matchmover.
- Since we work in 3ds Max, we have to work on the same axle system. Set Edit > Settings > Display “3D Up Axis” to Z. This is the default setting, but check it just to be sure.
- Go to Window > Track to display a timeline of the tracked data. Long green lines are good. Green means it is a good track and the longer it is tracked the better. Pay attention to decent track points with long green timelines. Make a note of your passport numbers – the good old pen and paper are the best.
- Go to 3D Scene > Coordinated Ordinate Systems. Set the origin point as a good track point.
- You need to set the distance between two points based on the size of an indicator in your scene. In this case, for example, the floor tiles are 30 cm apart, so select two points corresponding to the distance of a floor tile and enter them in the corresponding field on the right.
- Next, you need to set up your X and Y axes by selecting points that match these axes in your track. Find 4 track points perpendicular to each other or pick points perpendicular to their origin.
- When all this is done, click on the “Apply Coordinate System” button, then click on the small square “3D” button in the upper left corner of the Footage Viewer and it becomes 2D.
- When you get a decent track and have your co-ordinates set up, export as a Max script (.ms file) with camera animation settings. Save the matchmover file even if the track was not as good as we had hoped we might have to come back to it. Otherwise, we can now shutdown Matchmover.
- After opening a new scene in 3ds Max, go to Max Script > Run Script and select the scene you just created. Press C to activate the camera that is creating the script – this is the camera we want to render from.
Setting up the Render Environment in Max.
- Set your viewport background for the source video you want to model by right-clicking the “Realistic” text in the perspective window, clicking Configure > Background > Use Files, and then importing your PNG sequence. Select the “Animate background” check box. Be sure to click the Sequence check box in the File pane.
Next, go to Rendering > Render SetUp > Environment and set your PNG sequence as the environment. Select the Sequence check box again. When you render a frame, the environment may not be displayed correctly. This is usually because it is spherical by default. To fix this, open your material editor, drag the environment plan to a new slot, and click the Instance tab in the window that opens. In the Coordinates setting, set the mapping to Screen. This should make it flat so that it appears correct.
Now we want to test how good our track was. Create a simple box or two and place it on the ground and render a very small video. To hide all small tracking points during modeling, go to “Display Options” – the fifth tab in the creation window and enable “Hide Helpers”. Even at low resolution, you should be able to check whether the models in the video skip or fit correctly.
If your track was successful, the next step is to add HDR lighting and more detailed models, textures, etc. to make a more realistic shot.
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