- FemtoMega Multi-Device Synchronization Example
- 1. Project Background
- 2. Hardware Connections
- 3. Hardware Connection Guide
- 4. Network Connection Configuration
- 5. Software Configuration
- 6. System Product List
In fields such as medicine, sports science, and human factors engineering, dynamic 3D human reconstruction technology is gradually becoming a key force driving advancements in teaching and research. This technology captures and reconstructs three-dimensional data of human movement with precision, providing researchers with a new perspective to understand and analyze human structure and function. A broader commercial application of this technology is in volumetric video, which captures and reconstructs human bodies and objects in three-dimensional space to create holographic images that can be freely observed and interacted with in virtual environments. The FemtoMega multi-camera synchronization example serves as a foundational module for dynamic 3D human reconstruction technology, enabling synchronized collection of data from multiple RGBD cameras.
Adopting a Star-Type Connection Method (Professional Synchronization Hub) Note: Before testing, remove the white casing to expose additional interfaces.
One as the Master Device, Seven as Slave Devices.
Network Equipment Connections, a total of 8 RGBD cameras, and 2 switches are used. One switch connects four devices, and each switch's IP needs to be isolated (e.g., 192.168.0.1; 192.168.1.1), and the computer's 4 network card IPs need to correspond to the same subnet as the respective switches (e.g., 192.168.0.201; 192.168.1.202).
FemtoMega is an advanced iToF 3D camera jointly developed by Orbbec and Microsoft, serving as an official Microsoft-recommended alternative to the Azure Kinect DK. The FemtoMega depth camera incorporates Microsoft's latest advanced ToF (Time of Flight) sensing technology, offering identical working modes and performance characteristics as the Microsoft Azure Kinect DK depth camera.
The master device needs to send a trigger signal to the slave devices using a synchronization trigger line. The synchronization trigger line is depicted in the figure below:
For the Femto Mega synchronization trigger line with an 8-pin socket, here is a typical definition of pin functions, wire colors, and pin order.
Note: When the device is placed upright, the order of the pins from left to right is 1 to 8.
The front view of the multi-machine synchronization Hub is as follows:
Multi-machine Synchronization Hub's Two Sides Schematic：
Primary In ： "Indicates connection to the master device." Power 5v In： " translates to "Indicates that the Hub needs to be powered by a Type-C 5V power supply. (Logic Level is set to 1.8V by default)."
For a star-type connection, a single hub can accommodate up to 8 slave devices. Additionally, by using Hub-to-Hub connections, it is possible to expand the setup into multiple hubs.
Note: The Ethernet cables used to connect to the multi-machine synchronization Hub must be T568B-T568B cables.
Current test computer configuration (for reference):
- CPU: 11th Gen i7 / 2.5GHz * 16 cores
- RAM: 32GB
- Graphics: GPU NVIDIA 3060
- Operating System: Ubuntu 22.04
The recommended network cable standards are CAT5e and CAT6.
(2)A switch that supports Power over Ethernet (PoE) connection is essential for providing both power and data
- Device Connection to Switch Verified by Indicator Lights.
- Computer Connection to the Switch.
Start configuring the IP addresses for each device.
- Set the IP address for the master device, for example: 192.168.0.10.
- Set the IP address for the first slave device, for example: 192.168.0.11.
- Set the IP address for the second slave device, for example: 192.168.0.12.
- Continue this pattern for all devices, incrementing the last digit of the IP address for each subsequent device.
Note: After updating the IP address, an error may occur because the device cannot receive the return value after the IP update. It is necessary to manually reconnect using the newly set IP address.
Configure two network cards (NICs) on a Linux computer such that each is on a different network.
This sets eth0 to use a static IP address of 192.168.0.201, with a subnet mask of 255.255.255.0, and a gateway of 192.168.0.1.
This sets eth1 to use a static IP address of 192.168.1.202, with a subnet mask of 255.255.255.0, and a gateway of 192.168.1.1.
4.3.1 After setting up the IP addresses for your devices, you can perform a simple network test to confirm that your computer (PC) is connected to the devices.
Clone or download this repository. https://github.com/orbbec/MultiDevicesSync.git
"sn": "CL3N2410049",
"syncConfig": {
"syncMode": "OB_MULTI_DEVICE_SYNC_MODE_PRIMARY",
"depthDelayUs": 320,
"colorDelayUs": 0,
"trigger2ImageDelayUs": 0,
"triggerOutEnable": true,
"triggerOutDelayUs": 0,
"framesPerTrigger": 1
}sn: The SN number of the camera
syncMode: Specifies the synchronization mode of the camera; the master is set to OB_MULTI_DEVICE_SYNC_MODE_PRIMARY, and the slaves are set to OB_MULTI_DEVICE_SYNC_MODE_SECONDARY
depthDelayUs: The input delay of the ir/depth/tof trigger signal, in microseconds; (multiple cameras are sequentially spaced by 160us, such as device 1 at 0, device 2 at 160, device 3 at 320)
colorDelayUs: The input delay of the rgb trigger signal, in microseconds trigger2ImageDelayUs: The delay from the trigger signal input to capturing the image, in microseconds
triggerOutEnable: The enable switch for the device's trigger signal output delay
triggerOutDelayUs: The delay of the device's trigger signal output, in microseconds
framesPerTrigger: The number of frames captured per trigger, effective only in software trigger mode and hardware trigger mode.
Since the OrbbecSDK on Linux currently cannot discover devices with multiple network cards through network enumeration, we access devices by specifying their IP addresses. Example:
std::string ip_10 = "192.168.0.10";
std::string ip_11 = "192.168.0.11";
std::string ip_12 = "192.168.0.12";
std::string ip_13 = "192.168.0.13";
std::string ip_14 = "192.168.1.14";
std::string ip_15 = "192.168.1.15";
std::string ip_16 = "192.168.1.16";
std::string ip_17 = "192.168.1.17";
auto device_10 = context.createNetDevice(ip_10.c_str(), 8090);
auto device_11 = context.createNetDevice(ip_11.c_str(), 8091);
auto device_12 = context.createNetDevice(ip_12.c_str(), 8092);
auto device_13 = context.createNetDevice(ip_13.c_str(), 8093);
auto device_14 = context.createNetDevice(ip_14.c_str(), 8094);
auto device_15 = context.createNetDevice(ip_15.c_str(), 8095);
auto device_16 = context.createNetDevice(ip_16.c_str(), 8096);
auto device_17 = context.createNetDevice(ip_17.c_str(), 8097);#define MAX_DEVICE_COUNT 8ConnectionType connectionType = ConnectionType::LINUX_NET;To prevent potential interference when pointing in the same direction, a minimum delay of 160 microseconds is recommended. The actual pulse width is 125μs, but we declare it as 160μs to provide some leeway. Taking the NFOV resolution as an example, each 125μs pulse is followed by 1350μs of idle time. The purpose of staggering the exposure of two devices is to have the first pulse of the second camera fall within the first idle period of the first camera. The delay between the first and second cameras could be as low as 125μs (pulse width), but we recommend allowing some margin, thus 160μs. Given 160μs, you can stagger the exposure periods of up to 8 cameras at most. (In an eight-camera setup, a one-master-seven-slaves mode is adopted.)
cd MultiCameraSync
mkdir build
cd build
cmake ..
make -j
./MultiCameraSync
a. 8 units of Femto Mega cameras. https://store.orbbec.com/checkouts/cn/Z2NwLWFzaWEtc291dGhlYXN0MTowMUpCRTRIQ1E3WFZCR1QzSkJES0hCUU0zTQ
b. 8 units of 8P TO RJ45 conversion cables, Data Cable: EF2103 Multi-camera Synchronization Cable 8P TO RJ45, 0.15 meters. https://store.orbbec.com/products/sync-adaptor-for-femto-mega-and-femto-bolt
c. 8 units of Femto Mega Ethernet Multi-Camera Sync HUBs. https://store.orbbec.com/products/sync-hub-pro
d. 4 units of 5-port Gigabit PoE switches are recommended for purchase. https://www.aliexpress.us/item/3256803495017620.html
e. 8 units of 5-meter RJ45 Ethernet cables. It is recommended that the cables used to connect to the Multi-Camera Sync Hub must be T568B-T568B cables. https://www.aliexpress.us/item/2251832838246140.html
f. Lenovo Type-C Expansion Dock, USB-C to RJ45 Ethernet adapter, USB 3.0 hub, is recommended for purchase. https://www.aliexpress.us/item/3256805980059564.html
