Thread-safety of concurrent retrieve_image/retrieve_measure calls on a single sl.Camera

broncosin · March 26, 2026, 8:14am

We’re retrieving multiple streams (left RGB, right RGB, depth, pointcloud) after each grab() call. Currently these are serial. Is it safe to call retrieve_image and retrieve_measure concurrently from separate threads on the same Camera instance (each writing to its own
sl.Mat), or does the SDK require these to be serialized?

Myzhar · March 26, 2026, 5:12pm

Hi @broncosin
Welcome to the StereoLabs community.

We recommend calling retrieve* in the same thread as the related grab call.

If you want to process data in different threads, you can use the ROS 2 Wrapper code as a reference:

github.com/stereolabs/zed-ros2-wrapper

zed_components/src/zed_camera/src/zed_camera_component_main.cpp

master


      
          // ----> Retrieve Image/Depth data if someone has subscribed to
          DEBUG_STREAM_GRAB("Grab thread: retrieving Image/Depth data");
          processVideoDepth();
          // <---- Retrieve Image/Depth data if someone has subscribed to
          
          if (!mDepthDisabled) {
            // ----> Retrieve the point cloud if someone has subscribed to
            DEBUG_STREAM_GRAB("Grab thread: retrieving Point Cloud data");
            processPointCloud();
            // <---- Retrieve the point cloud if someone has subscribed to
          }