by 
Watch the tutorial
Step 1: Line up your two clips
Put the scene you want to leave first on your timeline, and place the clip with the moving object directly after it on the same track. In this example the first clip is a man sitting by a waterfall and the second clip is a train driving past the camera. Choose an object that moves clearly through the frame, ideally one that ends up covering most of the screen or leaves the picture entirely.
Step 2: Select the Object Mask tool
Find the Object Mask tool in the toolbar next to the timeline. Its tooltip reads that it finds and automatically masks objects, and a long press on the tool shows more masking tools. Select the second clip in the timeline, move the playhead to a frame where the object is clearly visible, then pick the tool.
Step 3: Hover over the object and click
Move your mouse over the Program Monitor. Premiere Pro highlights the object under the cursor, in this case the red train. When the whole object is highlighted, click it. The mask appears under Opacity in Effect Controls, where you can also see its Feather, Opacity and Expansion settings and a Tracker section.
Step 4: Track the mask
A mask on one frame is not enough, because the object keeps moving. In the mask's Tracker controls, click the track forward button. Premiere Pro shows a small Tracking window with the time remaining. Let it finish, or click Stop if you only need part of the clip. Afterwards, scrub through the clip to check that the mask stays on the object, and fix it by tracking again if it drifts.
Step 5: Isolate the object
With the mask tracked, you can use it to cut the object out of its background. Once the background of the clip is removed, only the train remains, and the area behind it is transparent. That transparency is what lets another shot show through behind the moving object.
Step 6: Stack and trim the clips
Hold Alt (Option on a Mac) and drag the masked clip up to the track above to make a copy. Trim the clips so the masked train on the upper track travels over the first scene, while the clip underneath changes at the moment the train covers the screen. In the video the finished timeline uses V1 for the two base clips and extra copies of the masked clip on V2 and V3. Play it back and the train now carries you from the first scene into the second. If you need more help with layering clips, our guide to masking in Premiere Pro covers the basics.
Tips
- Pick a clean subject. The tool works best when the object stands out from the background and does not hide behind other things.
- Check the edges. Zoom into the Program Monitor and look at the mask edges. A little Feather can make them look more natural.
- Add a sound effect. A whoosh or a train sound that matches the moment makes the transition feel complete.
FAQ
Where is the Object Mask tool in Premiere Pro?
It sits in the toolbar next to the timeline. A long press on it shows the other masking tools. It is only available in recent versions of Premiere Pro, so update the app if you cannot find it.
Why does my mask lose the object?
Move the playhead to where it goes wrong, adjust the mask and track again. Objects that change shape or leave the frame can need a second pass.
What kind of clips work best for this transition?
Clips where an object moves across the camera, such as vehicles, people walking past or a hand that covers the lens, work great.
Want ready-made transitions as well? Check out the Ultimate Premiere Pro Presets pack with 500+ presets.
