Rectifier Workflow

This tutorial will show you how to convert images captured with a camera model into a different camera model.

In this example we'll use as input a camera from our rig configuration file:

dwInitialize(&contextHandle, DW_VERSION, &sdkParams)
dwRig_initializeFromFile(&rigConf, contextHandle, rigConfigFilename);
dwRig_findSensorByName(&sensorId, cameraName, rigConf)
 
dwCameraModelHandle_t cameraModelIn = DW_NULL_HANDLE;
dwCameraModel_initialize(&cameraModelIn, sensorId, rigConf)

The following two snippets demonstrate how to initialize different output camera models.
contextHandle is assumed to be previously initialized dwContextHandle_t.

Example of camera for rectification (undistortion)

// Settings
dwPinholeCameraConfig cameraConf = {};
cameraConf.distortion[0] = 0.f;
cameraConf.distortion[1] = 0.f;
cameraConf.distortion[2] = 0.f;
// CODE: other settings of camera
dwCameraModel_initializePinhole(&cameraModelOut, &cameraConf, contextHandle);

Example of camera for model projection (simulation)

// CODE: create settings of simulated FTheta camera
dwCameraModel_initializeFTheta(&cameraModelOut, &cameraConf, contextHandle);

Use of the rectifier

The rectifier module can be initialized with the camera models that we have just created:

dwRectifier_initialize(&rectifier, cameraModelIn, cameraModelOut, contextHandle);

To create an image for where the output should be copied:

dwImageProperties imgProperties{};
dwSensorCamera_getImageProperties(&imgProperties, DW_CAMERA_OUTPUT_NATIVE_PROCESSED, camera);
dwRectifier_appendAllocationAttributes(&imgProperties, rectifier);
dwSensorCamera_appendAllocationAttributes(&imgProperties, camera);
 
// create images used by camera (output) and image rectifier
dwImageHandle_t inputImage = nullptr;     // the input image is got from the camera sensors.
dwImageHandle_t rectifiedImage = nullptr;
 
dwImage_create(&rectifiedImage, imgProperties, context);

And can be used on images coming from a live sensor or from a recording:

while(loop) {
    // CODE: get image from camera, stream it (optional)
    dwRectifier_setHomography(&homography, rectifier); //optional
    dwRectifier_warp(&rectifiedImage, inputImage, rectifier);
}

For simplicity, the actual sensor management, including retrieving images from a camera, is omitted in this tutorial.
For more information see Camera Workflow.

Finally all handles can be released:

dwCameraModel_release(cameraModelIn);
dwCameraModel_release(cameraModelOut);
dwRectifier_release(rectifier);
dwRelease(contextHandle);

For the full implementation refer to Video Rectification Sample.
See Rig Configuration for more information on Calibrated Cameras.