A well-placed surveillance camera could help a hotel company prove its case in court, but there’s more to it than just recording footage.
HOUSTON—Having security footage can aid both in monitoring for and reviewing any on-property incidents, such as slip-and-falls or an assault, but hoteliers need to make sure what and how they’re recording is useful.
There’s more to video surveillance and enhancement than what’s shown in crime procedurals and movies, explained Barbara Worsham, VP of animation, video and graphics division at Rimkus Consulting Group. Worsham gave a presentation at the 2017 Hospitality Law Conference titled “Caught on Camera! Defending Your Liability Claim through Video Enhancement & Analysis.”
What video enhancement can do
Essentially all types of video can be enhanced, Worsham said, including YouTube videos, cellphone video and dash cam footage. Companies can have low-resolution video full of visual noise that’s shaky with poor lighting, she said, and it’s still possible to enhance it (to various degrees) with state-of-the-art software.
Video enhancement doesn’t add anything that’s not already in the video, she said, but, for example, it can improve some lighting issues and reveal otherwise invisible details. Sometimes multiple frames focused on a specific object or person can be averaged together to give a sharper image, she said.
Sometimes, surveillance footage can help recreate the story, she said. In one video example, she showed footage of a woman who claimed a planter blocked her access to a railing, leading her to fall down some stairs. The DVR recorded footage from before and after the accident when the patio leading to the stairs was empty, she said, which allowed her team to map each of the individual stones in the patio’s flooring. By tracking the woman’s foot path across the stones, she said, they were able to determine she was actually walking down the middle of the stairs, not near the railing, where she claimed she was when she fell.
In another case involving a woman who survived being run over by a semi-truck, the surveillance videos from nearby businesses allowed them to recreate the scene in 3D modeling, Worsham said. After setting the scenario based on the footage, she said, her team was able to change the view of the camera in the 3D model, which disproved the pedestrian’s claims that the driver should have seen her.
Balancing cost and space against quality
Quality video costs more, Worsham said. Most security videos are recorded at a 320x240 pixel resolution, which can make it difficult to identify individual people in footage, she said. More pixels mean there’s more detail when particular sections of a video are enlarged, she said. More pixels also mean higher cost, she said, and require more space to store the video file, which is why most security footage has a lower resolution.
Lossy compression can save on required storage space, she said, but that class of data encoding creates compression artifacts, such as blocking pixels together. As an example of how this could cause trouble for hoteliers, Worsham cited a lawsuit in which the plaintiff pointed to a black shadow image on a compressed video as proof that a doormat wasn’t flat and thus had caused a fall.
Another cost- and space-saving practice that some companies use for security footage is lowering the frame rate, or number of still images recorded per second, she said. The standard frame rate for movies is 24 frames per second, she said, which is why the movement is so smooth.
“In security videos, one of the most common frame rates is five frames per second,” she said. “I am happy when I get five frames per second. I get so many that record at one frame per second. I even had a video last month recorded at one frame every two seconds. The worst was a frame every six seconds.”
Worsham presented a video showing a woman falling on a floor at different frame rates ranging from five to 30 frames per second. By increasing the rate to 10, it became clear the woman’s feet slipped out from underneath her. Though 30 frames per second showed the clearest video, she said that frame rate was a waste of storage space because 10 frames per second showed the scene clearly enough.
“If you have a low frame rate, you can miss what’s going on,” she said. “You’ll miss the ankle roll, that they caught the back of their own leg.”
A good rule of thumb is five to 10 frames per second works fine for most scenes, she said, and 15 frames per second is useful when trying to determine the speed of an object in the video.
A camera set to record when it sees motion seems like a great way to save on storage space, she said, but it could miss something that adds context to the situation. Another problem with motion detection is that there is a limited range in which motion can start the recording, she said, which means any motion outside of that won’t activate it.
“If you have a tiny video and need to identify someone, their face needs to be about one-third of the screen before you can get something beneficial,” Worsham said.
Consider the lighting conditions where the cameras are aimed, she said, because one area could be fine during the day, but be backlit at night so that shadows are cast where more light is needed to show detail. If the lights are controlled by time of day, she said, don’t forget to adjust the lighting as the days become longer and shorter throughout the year.
Many companies use a 30-day retention policy, she said, but some retain footage for 60 or 90 days. Whatever a company’s video file retention period, she said, it’s important to start with a written policy and then follow it. It would look strange in court if the written policy says 30 days but the footage was erased after five days. One of her clients, she said, has a practice of pulling the relevant DVR footage as soon an incident happens and storing it.
Before sending video in for enhancement, she said, look at the video to make sure the incident in question was recorded. Often, she said, she has received video files that do not show the incident because her client didn’t export the right camera.
Make sure the time stamps on the cameras and DVRs are correct, she said. Worsham said she once had a situation where a client’s video time stamps were off and, based on the time stamps, the footage showed the same person being in two places at the same time.
“That’s tough to explain to a jury,” she said.
Collect every camera view available, Worsham said, and show video one-half to two hours before and after the incident in question. Having the extra footage can provide some situational context, she said, and it can also show if someone planted something ahead of time.
Every step of enhancement needs to be documented from court, she said, proving that it’s the same video from beginning to end, so that someone else could perfectly duplicate the results using the same filters and version of software.