 Welcome to CardStunt as a Service, or CAS. CAS enables a massive impact crowd to create instant collective visualization using their mobile devices and cloud-based services. Here, we have a group of Mobus' fans who collectively want to show a message. When the fans receive a starting signal from the CAS coordinator, they raise up their phones for a short while. As soon as the coordinator chooses an image, the cloud assigns each of them a pixel from the image based on their position. Now, they are ready to convey their message with collective visualization. Let's take a look at how CAS works. As soon as the group is in place, the mobile devices observe neighboring devices. Each device shows its own identifier by displaying a color transition sequence. At the same time, each device identifies other devices within the camera's field of view and calculates the horizontal angular distances to each of them. All the observations are sent to the cloud and the cloud shapes the possible region of each device with observations from other devices. Then the cloud optimizes all the device's locations in or around their possible regions so that the reconstructed locations concur with the given observation results. Once the localization is completed, the stunt image is divided into tiles and dispatched to devices at the right locations. Thank you for watching our demo. Please refer to our paper for more details.