This topic explains how to run image acquisition and 3d data computation independently when using a single camera.
Please read the topics Opening a Camera and Grabbing 3D Data first.
Note: Rendering commands like RenderPointMap and RenderView use a single OpenGL context and therefore will be internally serialized and run sequentially, also when executed from separate Execute nodes. As these commands also have a single, global output node it is recommended to run at most one instance of each at a time.
Code Examples
Single Threaded
// Call the Open command to open the camera
NxLibCommand open(cmdOpen);
open.parameters()[itmCameras] = "1234";
open.execute();
// Create persistent command objects with two new, separate execution slots "capture" and "compute" under /Execute
NxLibCommand capture(cmdCapture, "capture"); // Create a new execution node "capture" under /Execute, to asynchronously run the cmdCapture command.
NxLibCommand computeDisparityMap(cmdComputeDisparityMap, "compute"); // Create a new execution node "compute" under /Execute, to asynchronously run the cmdComputeDisparityMap command.
// Note: the two command objects capture and computeDisparityMap now created two separate execution nodes /Execute/capture and /Execute/compute.
// Each of these nodes has its own Command, Parameters and Result subnodes and can be used to execute any command independently from commands
// any other execution slot.
// Note: when creating new execution slots their parameters will not be cleared after command execution and can be reused for the next execution in this slot
capture.parameters()[itmTimeout] = 200; // Set a capture timeout of 200ms
int numImagesCaptured = 0;
int numDisparityMapsComputed = 0;
// start the first capture command before entering the loop
capture.execute(false);
while (numImagesCaptured < 50) { // run loop until 50 images have been captured
if (capture.finished()) { // check if the capture operation is already done
if (capture.successful()) numImagesCaptured++;
capture.execute(false); // start the next image acquisition
}
if ((numImagesCaptured > 0) && compute.finished()) { // check if we already have an image and the last disparity map computation is finished
numDisparityMapsComputed++;
compute.execute(false); // start the next disparity map computation
}
}
printf("Captured %d images and computed %d disparity maps.\n", numImagesCaptured, numDisaprityMapsComputed);
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Multi Threaded
Note: The two command objects capture and computeDisparityMap in Thread 1 and Thread 2 create two separate execution nodes /Execute/capture and /Execute/compute. Each of these nodes has its own Command, Parameters and Result subnodes and can be used to execute any command independently from commands any other execution node.
Preparation (e.g. in main thread):
// Call the Open command to open the camera
NxLibCommand open(cmdOpen);
open.parameters()[itmCameras] = "1234";
open.execute();
// Note: when creating new execution slots their parameters will not be cleared after command execution and can be reused for the next execution in this slot
capture.parameters()[itmTimeout] = 200; // Set a capture timeout of 200ms
// capture one image synchronously so that the computation thread has an initial image to process
NxLibCommand(cmdCapture).execute();
... start thread 1 and thread 2 now
Thread 1 (capturing):
// Create command object working in a separate execution slot "capture" under /Execute
NxLibCommand capture(cmdCapture, "capture");
int numImagesCaptured = 0;
while (numImagesCaptured < 50) { // run loop until 50 images have been captured
capture.execute();
numImagesCaptured++;
}
Thread 2 (disparity map computation):
// Create command object working in a separate execution slot "compute" under /Execute
NxLibCommand computeDisparityMap(cmdComputeDisparityMap, "compute");
int numDisparityMapsComputed = 0;
while (numDisparityMapsComputed < 50) { // run loop until 50 images have been processed
compute.execute();
numDisparityMapsComputed++;
}
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