Apollo Rover Practice Shot

For all of you who've been waiting for an "out-of-this-world" shot, this is it—footage shot on the moon! Here, the lunar rover bounces across the lunar surface, driven by astronaut John W. Young during the Apollo 16 mission, April, 1972. Don't expect any re-shoots on this one. This shot is an advanced "final exam" shot inspired by the tasks of Magnificent Desolation. The source footage is an HD-resolution scan of the original NASA film.

You can download the Apollo.zip imagery and a final SynthEyes scene file in the example files section

Disclaimers: this exercise is provided for practice for users who are already capable trackers. A detailed step-by-step is not and will not be provided for beginners.  

When you open the shot, set the frame rate to 24 frames per second. Use the image preprocessor's region-of-interest to crop the image by cutting off the black top and sides and the rounded corners at bottom. Increase the queue length to the full shot length (173 frames). Depending on how much RAM you have in your computer, you may need to set the image preprocessor to luma-only also. You should definitely be able to get the whole shot into RAM—only about 250 MB is required in black and white.

Track a few supervised trackers through the length of the shot to use as guide trackers, since this is hand-held film. You will need to increase the search size, especially horizontally. Since this is a big pan, nothing stays on screen for the entire shot. You can track two trackers from the beginning forward into the shot, and two from the end back towards the beginning. 

Set up a very rough garbage matte for the rover—four corners will do. After it is complete, you can hide it so it doesn't get in the way.

Run a "Full Automatic" track and solve cycle. Even though it looks like a tripod shot, there was enough motion by astronaut/cameraman Charles M. Duke Jr. that a 3-D solution can be obtained.

Clean up spots where there are bad trackers, using the Tracker Curves graph to locate them, and Refine the solution.

You can leave the default coordinate system.  Because it is an almost-a-tripod shot, and possibly due to lens distortion, the ground is twisted up a bit. It is also possible that the cameraman was inside the bowl of a small crater.

You can now start tracking the moving rover, do a Shot/Add Moving Object. It will be fairly tricky to track things on the bouncing rover. Be alert for things that are floppy. One of the antenna-like structures in the sample solved scene does flop around quite a bit. The wheels are not usable either—they are on 4-wheel independent steering and suspension. There are also some shadows that are unusable because  the rover changes direction, in particular a large shadow on the back of the astronaut's backpack that would otherwise be very trackable. Be sure to find some things on the right side of the rover, not just on the more-visible left side.

After completing these tracks, you can solve to obtain the camera and object motion. 

At the least, you should set up the origin of the rover coordinate system, and a scale. By setting the origin, you will see that actual rover path, with the object null out in the midst of the rover tracking points. You also need to set the scale, to get the null and rover trackers moving in the midst of the camera trackers (rocks) properly.

To set the rover scale, note that there is a little rock that the rover goes right past. Track the rock as part of the camera trackers and refine, so that you have its 3-D coordinates. Set up a distance constraint between two trackers on the rover, and adjust the distance until the rover wheels pass right past the rock. You can adjust the distance and hit shift-G a few times to do this.

In the sample scene, a sphere has been placed roughly over the astronaut's helmet for illustration.

To add something to the rover alone, tracking the camera isn't really necessary. However, by doing it, you can see the full linear path of the rover, rather than just its motion within the camera framing.

 * The footage here is public domain, but it is not free to obtain and it requires some effort to make it usable. We've gone ahead and done so because we think it is such important and unique footage that it ought be more widely available.

SynthEyes easily is the best camera match mover and object tracker out there.

Matthew Merkovich

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