// Methods
/// <summary>
/// Configure the <see cref="ArucoCamera.ImageCameras"/>, the background that will display live webcam video through the
/// <see cref="ArucoCamera.ImageTextures"/>.
/// </summary>
/// <remarks>See https://docs.opencv.org/3.3.0/d4/d94/tutorial_camera_calibration.html and
/// https://docs.opencv.org/3.3.0/d9/d0c/group__calib3d.html#details for reference.</remarks>
// TODO: handle case of CameraParameters.ImageHeight != ImageTexture.height or CameraParameters.ImageWidth != ImageTexture.width
// TODO: handle case of CameraParameters.FixAspectRatio != 0
protected void ConfigureCameraAndBackground()
{
float imageWidth = CameraParameters.ImageWidths[cameraId];
float imageHeight = CameraParameters.ImageHeights[cameraId];
Vector2 f = CameraParameters.GetCameraFocalLengths(cameraId);
Vector2 c = CameraParameters.GetCameraPrincipalPoint(cameraId);
// Configure the camera according to the camera parameters
if (ImageCameras[cameraId] == null)
{
ImageCameras[cameraId] = GetComponent <Camera>();
}
// Estimate fov using these equations : https://stackoverflow.com/questions/39992968/how-to-calculate-field-of-view-of-the-camera-from-camera-intrinsic-matrix
float fovX = 2f * Mathf.Atan(0.5f * imageWidth / f.x) * Mathf.Rad2Deg;
float fovY = 2f * Mathf.Atan(0.5f * imageHeight / f.y) * Mathf.Rad2Deg;
ImageCameras[cameraId].fieldOfView = fovY;
ImageCameras[cameraId].aspect = ImageRatios[cameraId];
// Configure the background plane facing the camera
if (cameraBackground == null)
{
cameraBackground = GameObject.CreatePrimitive(PrimitiveType.Quad);
cameraBackground.name = "CameraBackground";
cameraBackground.transform.parent = this.transform;
cameraBackground.transform.rotation = Quaternion.identity;
cameraBackgroundRenderer = cameraBackground.GetComponent <Renderer>();
cameraBackgroundRenderer.material = Resources.Load("UnlitImage") as Material;
}
cameraBackgroundRenderer.material.mainTexture = ImageTextures[cameraId];
// Estimate background plane position relative to the camera, considering the first link in remarks: here x=0.5*ImageWidth and y=0.5*ImageHeight
// (center of the camera projection), w=Z=cameraBackgroundDistance and we are looking for X=posX and Y=posY
float posX = (0.5f * imageWidth - c.x) / f.x * cameraBackgroundDistance;
float posY = (0.5f * imageHeight - c.y) / f.y * cameraBackgroundDistance;
cameraBackground.transform.position = new Vector3(posX, posY * -1, cameraBackgroundDistance); // c=-1 for posY is because OpenCV (u=0, v=0) camera coordinates origin is top-left, but bottom-left in Unity (see https://docs.unity3d.com/ScriptReference/Camera.html)
// Estimate background plane scale, using the same equations used for fov but here we are looking for w=scaleX and h=scaleY
float scaleX = 2f * cameraBackgroundDistance * Mathf.Tan(fovX * Mathf.Deg2Rad / 2f);
float scaleY = 2f * cameraBackgroundDistance * Mathf.Tan(fovY * Mathf.Deg2Rad / 2f);
cameraBackground.transform.localScale = new Vector3(scaleX, scaleY, 1);
}
