Over Half a Billion Pixels – LEDs get Immense
There has been a lot of news recently about really big displays for different purposes. First there was the huge virtual production (VP) display in China and then news of a huge long LED display highlighting the Dubai Fountain.
Virtual Production Is a Hot Topic for LED Makers
Virtual Production has been a big topic for the large display industry for around five years. The basic concept is that a large LED wall is used as a background for video or movie content. The idea started back around the time of Covid, when it became impossible for productions to be made on location or involving international travel.
The Mandalorian, the blockbuster series from Disney+ was the first prestige project to really use virtual production (as far as we aware). The title started with the launch of Disney+ and the first series was completed conventionally but the second series was made and released in 2020 at the height of the pandemic. Several factors came together to enable the production using LEDs.
LEDs Had to Be Good Enough
First, the quality of LED displays had been improving for years after the development of blue LEDs, invented in the early 1990s by a team at Nichia in Japan. Before this. RGB and therefore full color, was not possible. However, diodes are difficult to control as they are digital and so really complex driving techniques have to be used. That can make it hard to develop accurate colors and brightness, especially at low gray levels close to black. Those low gray levels are often what colorists and others look for in cinematic content.
Controlling the consistency of the image quality, especially over the life of an LED display is really tricky and is a key difference between the highest and lowest quality displays. It took a long time for engineers to develop really high quality blue LEDs, with ‘just the right blue’ and with tight control of image quality.
GPUs Also Developed
As LEDs were getting much better, so were GPUs and the 3D graphics engines such as Unreal. By capturing metadata from digital cameras and lenses, computing systems based on high power GPUs could be used to render the images on the LEDs with characteristics optimized for the camera being used. Landscapes and backgrounds could be rendered in real time rather than in post production. Further, having a real background could make it easier for actors to engage with the production.
New RGB lighting was also developed to complement the backgrounds and to provide the right kind of high visual quality ‘look’ that directors and cinematographers were seeking. It’s not enough to simply use an LED background; effects such as reflections on objects in the scene need to be consistent. (By the way – this is a dramatic simplification – the reality is that the kind of very pure red, green and blue light from typical LEDs can make colors seem quite different than when they are viewed in natural light – that’s a whole technology deep dive!). Directors (and their money people) liked that they could adjust lighting and, for example, switch season or time of day or the appearance of the weather instantly.
You Need an Industry
Now, developing a new technically demanding application for large LED walls might not have got the full attention of LED wall makers. However, a large part of the LED display industry was and is the rental market – the supply of panels for concerts, trade shows and other events. Of course, during Covid, this market shrank immediately to zero, so LED makers had a good reason to develop products that were suitable for virtual production.
LED display makers also had production capacity available. In the early days, it was expected that VP stages (or ‘volumes’ as they are known, would be regularly re-built and re-configured so the kind of mechanical robustness and flexibility of panels for the rental market seemed ideal. In fact, we have heard that VP volumes are relatively rarely re-configured so designs more like fixed installation products.
High Resolution is Essential
High resolution is a critical part of the equation for VP volumes. Because the camera may zoom in, you really need more resolution on the display than is in the camera sensor. Resolution also has to be managed for the avoidance of moiré – the interference pattern that can be seen if you have two patterns that are nearly, but not quite, the same. A range of different solutions including optical filters can be used to minimize the impact of moiré.
A New Volume in China
The big display that prompted this article is the virtual production facility built by Absen in Deqing, China and claimed to be the largest VP volume in the world. It’s 50m in diameter and has a height of 12m while wrapping around 270 degrees of a circle. We have reached out to Absen and are still hoping to hold an interview with the firm, but have seen comments in other media that the display is claimed to have 600 million pixels. The area of the video wall is around 1,700 m2 and the total floor area is 5,000 m2.
We have seen reports of 600 million pixels being on the screen. A total of that number would mean around 352K pixels per square meter – or 594 pixels per linear meter) which equates to a pixel pitch of around 1.7mm. That seems reasonable for a high end video wall. It would also mean a horizontal resolution of 70K and a vertical resolution of just over 7000. Our calculation, then, is that the display is the equivalent of around eighteen 8K displays in terms of resolution. There’s a video from Absen about the display here.
Display Makers have Evolved
The development of VP volumes has meant interesting evolutionary changes for the LED display industry. Increasingly, the need to coordinate the cameras, processors and other elements of the process has made systems more complex, so that LED companies, such as Absen or Infiled have been positioning themselves as system suppliers, not just providers of LED walls.
Dubai Has An LED More than a Quarter of a Mile Wide
The second big project that caught our attention this week was an installation of a huge LED wall in front of the ‘Fountain of Dubai’ by Infiled. The LED is 440 meters long (1.440 ft or over a quarter of a mile!) The 1,254 m2 wall uses 3.9mm pitch LEDs and has ‘just’ 80 million pixels – or the equivalent of 2.42 8K displays. The wall is the subject of a video from Infiled.
