Convert cv::Mat to openni::VideoFrameRef - c++

Question

I have a kinect streaming data into a cv::Mat. I am trying to get some example code running that uses OpenNI.
Can I convert my Mat into an OpenNI format image somehow?
I just need the depth image, and after fighting with OpenNI for a long time, have given up on installing it.
I am using OpenCV 3, Visual Studio 2013, Kinect v2 for Windows.
The relevant code is:
void CDifodoCamera::loadFrame()
{
//Read the newest frame
openni::VideoFrameRef framed; //I assume I need to replace this with my Mat...
depth_ch.readFrame(&framed);
const int height = framed.getHeight();
const int width = framed.getWidth();
//Store the depth values
const openni::DepthPixel* pDepthRow = (const openni::DepthPixel*)framed.getData();
int rowSize = framed.getStrideInBytes() / sizeof(openni::DepthPixel);
for (int yc = height-1; yc >= 0; --yc)
{
const openni::DepthPixel* pDepth = pDepthRow;
for (int xc = width-1; xc >= 0; --xc, ++pDepth)
{
if (*pDepth < 4500.f)
depth_wf(yc,xc) = 0.001f*(*pDepth);
else
depth_wf(yc,xc) = 0.f;
}
pDepthRow += rowSize;
}
}

Answer 1

First you need to understand how your data is coming... If it is already in cv::Mat you should be receiving two images, one for the RGB information that usually is a 3 channel uchar cv::Mat and another image for the depth information that usually it is saved in a 16 bit representation in milimeters (you can not save float mat as images, but you can as yml/xml files using opencv).
Assuming you want to read and process the image that contains the depth information, you can change your code to:
void CDifodoCamera::loadFrame()
{
//Read the newest frame
//the depth image should be png since it is the one which supports 16 bits and it must have the ANYDEPTH flag
cv::Mat depth_im = cv::imread("img_name.png",CV_LOAD_IMAGE_ANYDEPTH);
const int height = depth_im.rows;
const int width = depth_im.cols;
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
if (depth_im<unsigned short>(y,x) < 4500)
depth_wf(y,x) = 0.001f * (float)depth_im<unsigned short>(y,x);
else
depth_wf(y,x) = 0.f;
}
}
}
I hope this helps you. If you have any question just ask :)