I have difficulties to remove static objects on the background

Hi everyone, I started using mocha not long ago and I am still green in compositing and very new to this forum so please forgive me if I ask any stupid question.
I have a shot which is a lock-off long shot with a slight pan from right to left with a guy running on a dirty street. I want to remove all static objects on the background and keep the running guy on the foreground which I don’t have much success. I made the first frame in the sequence as a clean plate done in photoshop. I made a spline to track the whole frame then I import the clean plate single image in the Insert Clip column under layer properties of this layer and press Align Surface so the plate lay on top of the sequence as the original plate size. I also made another rough roto layer for the running man. When I play the clip it looks good with the clean plate following the perspective change with the track layer but I can’t figure out how to review the man and make him appear on top of the import clean plate. Also at the end of the shot there is some new area exposed on the left hand side which have some brightness difference with the clean plate. Is there anyway I c
an blend the clean plate and the last frame in mocha or if I have to make the last frame another clean plate and color match these 2 frames in Photoshop?
Am I going the right path or if there is a work around/ better way to do this?
Also there is a shot in mocha 2011 customer showreel at about 1:23 which the sign is removed on the backgruond while the camera is moving and people walking pass on the foreground etc… Could anyone please explain me the detail mocha workflow of that shot? I have some shots on hand need to be done which are exactly like this but I still could figure out how to do that yet.
Thanks for your patient to read this and I appreciate any help.

I’m not exactly sure what you’re trying to accomplish by removing the background. What I can tell you is that in my experience you’ll have to generate several clean plate backgrounds when you’re dealing with color changes. When you import your cleanplates, you can tell Mocha which frames or groups of frames to apply that clean plate to. For example, your first cleanplate is used for frames 1-26 and the second one for 27-300. The second clean plate should be generated using one of the frames that has the color change and the runner removed using Mocha’s remove module. Mocha will try to blend between the cleanplates.

Hi tokutoshi,
You’ll need the remove module to use a clean plate to remove objects in the scene with mocha.
The removal features you are talking about are available in mocha Pro. You can check the differences between products here:

hmmm. sounds like you want a layer with just the running man isolated, so you can put something new behind him.
You need to rotoscope the man out.
While you could use your tracking data and your cleanplate from photoshop in after effects, shake or some other compositing too, to pull a difference key, it is unlikely you will get a nice key on the running man as a result. You might get some hair detail or a few key areas, but usually, if it wasn’t shot over a green screen, you’re not going to get very far without manually drawing shapes for the matte.
Luckily, you can use Mocha to help with that process. You can draw your shapes around different parts of the man and let mocha track them so they somewhat “stick”… like an arm, or the head or the lower leg, foot, etc…
it’s not going to be perfect, but it will, in many cases, eliminate 1/3 -3/4 of the amount of keyframes you need.