Loading the Targa Sequence and Movie File into Video Post

Now we can take our sequence into Video Post so that we can composite it with the image we want in the mirror. Loading a sequence of files in a MAX file-selector dialog box requires an Image File List file, or .ifl. An IFL is a text file listing the files in sequence. If you’re the sort of person that enjoys such things, you can create it yourself in a text editor. Normal people can generate it automatically in the file-selector dialog box.

1.  Make sure your Targa files (alpha_mirror0000.tga to alpha_mirror0180.tga) are on your hard drive, either where you rendered them or copied from the CD. Also copy ghost_image.avi from the chapter 12 folder on the CD to the same directory as the Targas.

2. Open your alpha_mirror.max file or load it from the CD. Open Video Post. Click Add Image Input Event. Set VP Start Time to 0 and VP End Time to 180. Click the Files button. Navigate to the directory on your hard drive with the Targa files. Click the alpha_mirror0000.tga file in the files window.

3.  Check Sequence and click Open. This brings up the Image File List Control dialog box. Click OK; this creates an IFL file listing all your frames. Click OK again to close the dialog box.

4.  Click Add Image Input Event again, and this time select ghost_image.avi. It comes into the queue after the IFL file. This is correct, because we want to see the image through the “hole” in the bathroom scene created by the alpha channel.

Compositing the Files Together

1. Select the two image events in the queue and click the Add Image Layer Event button. Choose Alpha Compositor from the drop-down in the Add Image Event dialog box, and click the Enabled button.

2.  Click the Files button under Mask and choose the alpha_mirror.ifl file again. We want to mask the image with its alpha channel, so leave Alpha Channel selected in the drop-down.

3.  Click somewhere off of the events to deselect them. Now what do we have left to do? A gold star if you said, “add an image output event” or even “save the darn file, bozo.” Click the Add Image Output Event button. Click Files and save the file as ghost_mirror.avi. Your queue should look like this:

4.  Click Execute. After rendering, you should have an AVI file with the “ghost” appearing in the mirror, with the mirror reflections still appearing on the surface of the mirror. A sample frame from the avi is shown in Figure 12.13.

FIGURE 12.13  This shot is from the AVI version of the ghost scene.

TIP In certain other 3D applications, you can take compositing of reflections to another level. You can render out each layer (reflections, specular, diffuse, etc.) in a separate pass, to be composited together later. This way you can tweak just the value of the specular highlights, for example, without having to re-render the whole thing. We need this option in MAX. Tell the developers you’d like to see it in MAX R4. Keep your eyes open; maybe someone will write a plug-in or a script before then.

Summary

In this chapter, we’ve explored the post-production capabilities available within the Video Post dialog window. We discussed the VPQueue and how to understand the way it interprets the events you enter. We learned how to add scene events and image input events, including bringing in sequences of still images. We discovered how to add image filter events and looked at the various filters available in Video Post. We learned how to cut between shots, cross-fade between them, and composite them using alpha channel information. We discussed the nature of alpha channels and why they are so crucial to compositing. Finally, we put it all together with an advanced exercise in compositing, using special materials to get the alpha channel and image we needed for the composite.

In the next six chapters, you will enter the world of MAXScript, MAX’s built-in programming language.

© 2000, Frol (selection, edition, publication)