MPM chooses Digital Projection for an innovative Cave at CEA Tech

The integrator MPM equipment uses the E-Vision Laser 10K projector Digital Projection for a temporary installation in a Cave, located in one of the laboratories managed CEA Tech.

With more than 3.300 m², the laboratory of CEA in the French city of Grenoble - known as Y.Spot– is an open innovation center used to develop a broad portfolio of technologies for energy and healthcare, as well as to disseminate new technologies for the industry, bridging the worlds of research and business.

Through his work at Y.Spot, that welcomes collaborations with the industry, SMEs, students, architects and designers, CEA Tech (technological branch of the French Atomic and Alternative Energy Commission – CEA) also provides businesses with access to key enabling technologies, as well as those developed by other operating divisions of this entity.

Like CEA Tech, the integration specialist MPM equipment It also carries out its work in various sectors, since it began with installations in theaters, concert halls and museums, and then went on to work in conference rooms, of meetings and sports venues in the MICE environment.

“We also help clients digitize their offering with new communication tools through Byod (bring your own device) or automation - explains Nicolas Jeanselle, MPM Equipement project manager. We are proud to be specialists in all things audiovisual and we work to make everything work and communicate together. Cave technology (immersive virtual reality environment) It's not particularly our specialty., but this project goes further”.

Sirce development

The installation, called Syrian (Smart immersive room for circular vision experiment), It was designed by the engineer and set designer Frédéric Ravatin, of the company Creatime, in the form of three truncated pyramids, with a base of 5 m² (variable +/- 10% depending on the prototypes and space configuration).

Inside this space, The floor and three of the walls serve as screens with 3D relief that can be used to recreate environments and objects, and even host videoconferences also in three dimensions.

Although the Cave can accommodate up to twenty-five people, It is usually used by between five and ten. In the same, All visitors are invited to wear active glasses Xpand 3D to have a feeling of total immersion when stereoscopic content is projected on the four synchronized and aligned screens.

Since the faces of Sirce are inclined inwards with an angle of 26 degrees, significant perspective distortions can be induced and exaggerated in stereoscopy, making the virtual environment appear much larger than it actually is.

This way, the user can feel that he looks 'beyond'’ from the confines of the Cave, recreating a bigger world, whose dimensions and space still seem 'normal'’ (a phenomenon known as ortoestereoscopia).

Project perception

“The set designer of the project won the competition for the remodeling of the CEA Y.Spot, where the Cave is installed -Jeanselle remembers-. The idea was to create a virtual environment in which any media and content could be displayed in an immersive way.”.

Besides, MPM Equipement had already worked with Frédéric Ravatin on several projects, among them in the largest freshwater aquarium-museum in Europe: Aquatic, located in Switzerland.

After a long period of testing, The MPM team deduced that the only method that could be used to compensate for the deformations induced by tilted screens was to recreate the path that light would take from the observed object to the viewer's eyes., simulating on screens, to a pixel, where the light beam should pass through if the viewer were really in that virtual environment.

As Jeanselle points out, “we were, indeed, projecting people's perception”. So, Two virtual cameras were placed for each screen, located approximately where the viewer's eyes would be (to some 1,6 m from the ground, in this case); one for the left eye, drawn in red, and another for the right eye, in blue.

Each of the four projection surfaces (left, frontal, right and ground) requires two cameras, which gives a total of eight, grouped into four teams of two. The left and right cameras of each team were separate 6,5 cm (the average distance between both eyes) and perfectly parallel, no convergence.

“This information is recorded, allowing us to create a synthetic model of Sirce at the appropriate scale, thanks to the fact that the dimensions and angles taken are recorded with a laser measurer. Next, we use the same cameras as if they were projectors, texturing the interior faces of the Cave”, Jeanselle points out..

Once the information is recorded, sent in real time, what it is used for TouchDesigner of Derivative, five teams E-Vision Laser 10K from the manufacturer Digital Projection to project it in Sirce.

“We needed a low maintenance unit, able to supply 10.000 lumens, with a very short range lens that could be on axis with the center of the Cave - Jeanselle continues -. The laser was also mandatory from an environmental point of view, in addition to ensuring low noise and heat generation in the relatively small tent”.

Digital Projection projectors, as this expert assures, “met all these criteria and more, at the same time they had a very good price considering their performance and quality. It also provided us with a partner who could accompany us throughout the conceptual phase and beyond.”.

For this application the video projector had to be fed with two video streams of 120 Hz (a connection mode called Dual Pipe), to allow each unit to switch very quickly at a precise frequency between two video sources, in this case, left and right eyes.

Solve this issue, to which was added that the projectors had to be capable of handling many different types of 3D, led to a complex calibration period for the equipment, as Jeanselle points out.

“It was a long process, but the quality of the industrial calibration that was done before receiving the projectors was impressive. There was no discrepancy between each unit, even if they were not exactly the same batch. Digital Projection was fantastic throughout the entire process and lent us the projectors for weeks so we could test them with the rest of the devices and content.”.

In this sense, Jeanselle remembers that “Stephane Bourdon, Sales Director of Digital Projection in France, and his team were always available; there were no problems, They stuck to the agreed dates and dedicated a lot of effort to the pre-sale. Simply, We couldn't have done the job without them.”.

Although the finishing touches to the installation had to be postponed due to the continued disruptions caused by COVID-19, Jeanselle notes that the client was very happy with the project so far.

“If a spectator stands in the exact position of the cameras, the illusion is perfect, even in stereoscopy. The experience we have acquired in the prototype phase, combined with advanced hardware and software, has allowed us to maintain the highest quality of immersion. Even with half a dozen simultaneous viewers, the effect is still incredibly striking”.

For Tiana Delhome, director of hospitality by CEA Y.Spot, “The MPM team has guided us very well in what was a very complex and innovative project, showing great availability and flexibility on many occasions, in addition to meeting all deadlines. We are very happy with the finished device and hope to benefit from it for years to come.”.