# Structured Light Patterns Work Like a Hologram
## 7 Transmission of 3D Holographic Information along the Radio Channel  
As mentioned in the Introduction, the transmission of holographic information along communication channels involves the problem connected with the high capacity of holograms. The possibility of efficient compression of holographic information, similar to the transmission at one sideband known in radio electronics, was demonstrated in patent RU 2707582 C1 [7]. In this situation, as shown in [14], this compression is already sufficient for the transmission of 3D holographic information along the radio communication channel. It is even more so if, as described above, the transmission of one of the two components of 3D image basic modalities (depth maps of the holographed 3D object) is replaced by the structured light pattern formed by photo capture of the lateral projection of straight fringes on the 3D object. Indeed, in this case, the load on the communication channel and computational resources at the receiving end decreases more substantially. Along with the texture of the 3D object surface, not two 2D frames but only one is transmitted, though it will be somewhat wider than that in the conventional standard, or two 2D frames but with the second one possessing an order of magnitude lower resolution than the first one in the plane perpendicular to the initial direction of structured light fringes. In fact, even the necessity to form the second frame disappears. All its information is fitted into a small additive to the first frame with the texture, similar to the case of analog TV frame encoding when each scanned line ends with the operation information concerning line or frame change. However, in our case, the amount of operation information is larger, and this is more like the wide-screen frame format. As described above, diffraction at the structured fringe pattern forms a 3D image of the depth map of the holographed object. The experimental transmission of this compressed information along a wireless Wi-Fi communication channel, with a frequency bandwidth of 40 MHz, and a frame rate of more than 25 frames per second has been described in the conference proceedings [27]. Developing the obtained result, we repeated the experiment on the transmission of holographic information of 3D images along a wireless Wi-Fi communication channel for 3D video transmission with the help of the FTP protocol. In this case, each transmitted frame of the 3D image was one 2D frame--texture (2000 \(\times\) 2000 pixels) and the pattern of structured fringes (25 \(\times\) 2000 pixels) (Figure 16). To imitate the transmission of a video sequence, the packets containing 291 such frames were transmitted simultaneously. The time of packet transmission, measured by the FileZilla software, during real-time representation shows that the transmission of the complete holographic information about a dynamic 3D object is quite implementable both for the frame standard similar to HD and for the Full HD. In the experiment on the transmission of holographic 3D video, the transmitted 2D frames composed of the texture and the operation information were formed with different compression degrees. All frames were preliminarily prepared in the following formats: BMP (without compression), PNG (compression without losses), and JPEG (compression with losses, 70% quality). Experiments were carried out for each of the listed formats. The sizes of frames with texture and mask were chosen in the following combinations:  
* 500 \(\times\) 500 pix. texture + 25 \(\times\) 500 pix. structured fringe pattern;
* 1000 \(\times\) 1000 pix. texture + 25 \(\times\) 1000 pix. structured fringe pattern;
* 2000 \(\times\) 2000 pix. texture + 25 \(\times\) 2000 pix. structured fringe pattern. For convenient test transmission, all frame sets were packed into uncompressed ZIP archives. Results of the measurement of packet transmission time were processed and are shown in Table 1.