App lets iPhones shoot time-lapse, without having to stay in one place
While time-lapse videos can be quite striking, creating them usually involves leaving the camera in one place for the duration of the shoot. A new app allows such videos to be recorded on a smartphone, which can be moved and used for other things between shots.
Ordinarily when shooting time-lapse footage, a camera is placed on a tripod or otherwise locked in place, then left to capture a series of still images at regular intervals. When those images are subsequently all viewed in succession, the recorded action – which may have taken place over hours, days, weeks or longer – is condensed into the space of seconds or minutes.
In order to keep the video smooth, the camera can't be moved for the entire recording period, unless it's being intentionally (and very slowly) panned or tilted. This means that the photographer either has to stay with the camera the whole time, or set it up someplace where it's unlikely to be stolen or damaged.
Additionally, the camera can't be used for anything else while it's shooting time-lapse. Needless to say, this could be pretty inconvenient if the camera was integrated into the photographer's I-need-it-for-everything smartphone. That's where the ReCapture augmented reality app comes in.
Created by a team of researchers at Cornell University, the iOS app allows the user (and their iPhone) to come and go from a specific location, shooting aligned images of the same subject every time they're there. They use the app in different modes, depending on what they're shooting.
Overlay Mode, for example, is good for wide shots where extremely exact alignment between shots isn't too important. When utilizing it, the user starts by shooting an initial image. Using their GPS coordinates, the app subsequently guides them back to the same location, each time overlaying a translucent version of the previously-recorded shot on their viewfinder screen. The user then just aligns the current shot with that overlay.
When shooting close-ups, where even minor inconsistencies in alignment will show up more, the user selects 3D Capture Mode. It goes further than Overlay, by utilizing the phone's onboard IMU (inertial measurement unit) to gauge its position in three-dimensional space. It then guides the user in the precise positioning of the phone, by displaying directional arrows on the screen.
Finally, Light Field Mode "collects a range of images that can be used to reconstruct the scene in 3D offline." Regardless of the mode(s) being used, the app allows for multiple time-lapse videos to be shot at the same time, with the user going back and forth between the various locations.
A paper on the study, which is being led by Asst. Prof. Abe Davis and computer science major Ruyu Yan, was recently presented at the 2022 Association for Computing Machinery (ACM) Symposium on User Interface Software and Technology.
ReCapture is available for free via the App Store, and is further explained in the video below.
Source: Cornell University