Why do we need calibration and clever software?
Dome projection has a field of view close to 180º from left to right and front to back of the dome screen. That is much wider than the human eye field of view, and that what makes the dome an immersive environment.
Such a wide field of view means a lot of pixels are needed for a clear image, and in theory, the number of pixels required is independent of dome size. However, 8K resolution seems to be more than adequate in very big domes and 4K resolution in medium-size domes. For small domes, a lower resolution is often acceptable.
When Fulldome.pro entered the dome projection market in 2010, there were no 4K projectors. Back then, the only way to get higher resolution in a projection dome was to combine images from multiple projectors.
And that’s where calibration comes in. When more than one projector is used, we must align them to cover the full screen, split the content between the projectors, and mask and blend images where these projections intersect.
Before digital calibration, this had to be done manually. The process of masking and blending could take hours or even days. Even after slight adjustments like moving projectors or replacing lamps, the calibration had to be done all over again. The difficulty with setting up and maintaining dome projection had limited mobile domes to the single projector systems with low resolution.
This, in turn, limited the size of mobile and portable domes. High-resolution immersive dome experiences like Samskara – did not exist.
How it works
After installing the projectors and pointing them in roughly the right direction, a camera with a fisheye lens is placed in the center of the dome. The operator connects the camera to the single media server and starts the calibration process. Our fully-automated calibration software takes care of the rest.
Each projector displays a series of patterns on the screen, which are captured by the camera and analyzed. The software works out where each projector overlaps with others and maps the intensity over the entire screen. With our DX4 projection systems, a full calibration is completed in under 15 minutes. When calibrating systems with eight or more projectors, masks and blends for multiple projectors are calculated simultaneously – so the process is still really fast.
In most cases, calibration only needs to be performed once for a perfect dome image. But there are times where a few tweaks may be required. Settings can be adjusted to compensate for stray light, objects inside the projection dome, and other factors. Once these parameters are set, the system will be able to calibrate despite the interference.
Fulldome.pro technology allows using relatively low-cost projectors, which in turn lowers the cost of high-quality dome projection systems. Even though 8K projectors are becoming available, using multiple FullHD or 4K projectors will produce better results at a lower overall cost.
Another great feature is that the calibration process is managed from the iPad interface and is run from a single Media Server. There is no need for a dedicated server room or a team of IT staff to support it.
Why we love it
Our auto-calibration system made the previously tedious task fast and efficient, cutting down projection domes installation time and costs. Any project manager or a team member can be trained to complete a calibration process with our user-friendly technology.