Car removal

Hey Guys,

Been playing with the trial of Mocha Pro to see if I could remove the red car from the shot below, really not having much luck, I think maybe due to the slight rotation and the fact the camera is moving aswell as the red car, any tips, this even possible to remove? Results with clean plates were terrible :slight_smile: Thanks for any advice.

John.

You need to have a holdout matte for the FG bushes. You need to have a rock solid track on the ground and any other planar data the car passes over. I have a complex remove tutorial that might help here: https://borisfx.com/videos/mocha-pro--solving-complex-object-removes/

Basically, look for the planes of motion, this is a little bit more of a complicated shot than it looks due to occlusion and speed.

Please let me know if you have any questions and I will be happy to help you.

Cheers,
Mary

Thanks Mary, it was actually after watching your complex object removal tutorial that made me give this a try :smiley: It just doesn’t seem to be able to use the ground before and after the car to remove the car. Well maybe it does I just can’t get it to do it :smiley:

John.

Hi Jon,

That sounds like a bad track then, try tracking more ground pixels and seeing if you can get a better track that way.

Thanks Mary, Does it matter the order in which I track the different elements? Also should be enabling perspective for any tracks? In your expert opinion should Mocha be able to remove this ok? :slight_smile:

John

Yes, always track FG elements to BG elements, and keep the foreground elements at the top of the layer pile in descending order. Keep perspective on, but turn it off where the track gets lost and back on where you need it.

If you can get a good track, this should remove OK, but you might add motion blur to hide any sins. This is not an “easy” remove, because it is not an “easy” track with lots of overlapping data.

I downloaded this footage from YouTube and decided to give it a try. In order to track the shot I tracked a big square that stays in the shot the entire time (with perspective) since trying to track areas that move off the screen is a lot harder to get right. Then I created two squares back by the area the car moves through and just parented them to the tracked base area. Then I tracked the car. For the remove I used None for the illumination model since the other options just copied all kinds of edges and noise into the car area. End result isn’t awful, but the removal isn’t perfect. I see this a lot on removes I try to do. It has this kind of noise/banding that generally requires I render out a matte of the object and then clean up with blur or paint effects. Is there some better way to handle this removal artifact?

Hey Matthew,

Much better than what I was getting :smiley:

When you say you created two boxes back by the car where both boxes tracking the car but one is for the background? How did you parent the two car boxes to the tracked base area.

Thank you :smiley:

John.

Sorry didn’t notice the overlapping boxes in the original picture had to enlarge it :smiley:

Going to try now.

John.

Trying to track the area the car moves through is kind of difficult due to the camera motion. But that area way at the back stays in frame the entire time and gives a really solid track. Using the ability to parent x-splines you don’t have to track the background removal splines, they will just follow along the tracked spline. Had to use two of them to fully cover the area. The end removal is actually pretty decent. Didn’t really need to mask out the bushes that slightly obscure the car even. But the road has a slight color/banding issue. You can see it in the corner of the full frame. It changes as the shot goes, it’s not horrible but it’s far from what I’d call perfect. It happens a lot when using the removal feature. I see it when I do clean plates and removals as well. Sometimes you can minimize it with the illumination options but more often than not it makes it worse not better.

Here’s the result I got

I only spent about 10 mins doing it so I’d take it with a grain of salt. But I’d love to hear ideas on how to work with the removal artifacts.

In order to parent a layer use the “Link to track” option in the layer properties.

linktotrack2

Try tracking the shot from the end to the beginning, and instead of creating a bunch of shapes, order your file like this:

Track and Roto your car.
Make a large shape around the car and background to track, go to link to track and set it to none, and then tracj from the end of the shot to the beginning.

See if you can get a remove that way?

Have you watched our remove module overview videos? They really help understand what Mocha needs for a solid remove. The best tutorials for remove are the following, we have a video series on the basics of the remove tool, part 1, 2, and 3:

Cheers,
Mary

Thanks Matthew and Mary,

I’ve managed to get it to look like Matthews video so massive amount of progress made since yesterday :slight_smile: I’ll try tracking backwards now Mary and see how that goes. I have watched all the videos, makes it look so easy :wink:

John.