Kinect v2 developer preview + OpenCV 2.4.8: depth data

This time, I'd like to share code on how to access depth data using the current API of Kinect v2 developer preview using a simple polling, and display it using OpenCV. Basically the procedure is almost the same with accessing color frame.

In the current API, depth data is no longer mixed with player index (called body index in Kinect v2 API).

Disclaimer:
This is based on preliminary software and/or hardware. Software, hardware, APIs are preliminary and subject to change.

//Disclaimer:
//This is based on preliminary software and/or hardware, subject to change.

#include <iostream>
#include <sstream>

#include <Windows.h>
#include <Kinect.h>

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/contrib/contrib.hpp>

inline void CHECKERROR(HRESULT n) {
    if (!SUCCEEDED(n)) {
        std::stringstream ss;
        ss << "ERROR " << std::hex << n << std::endl;
        std::cin.ignore();
        std::cin.get();
        throw std::runtime_error(ss.str().c_str());
    }
}

// Safe release for interfaces
template
inline void SAFERELEASE(Interface *& pInterfaceToRelease) {
    if (pInterfaceToRelease != nullptr) {
        pInterfaceToRelease->Release();
        pInterfaceToRelease = nullptr;
    }
}

IDepthFrameReader* depthFrameReader = nullptr; // depth reader

void processIncomingData() {
    IDepthFrame *data = nullptr;
    IFrameDescription *frameDesc = nullptr;
    HRESULT hr = -1;
    UINT16 *depthBuffer = nullptr;
    USHORT nDepthMinReliableDistance = 0;
    USHORT nDepthMaxReliableDistance = 0;
    int height = 424, width = 512;

    hr = depthFrameReader->AcquireLatestFrame(&data);
    if (SUCCEEDED(hr)) hr = data->get_FrameDescription(&frameDesc);
    if (SUCCEEDED(hr)) hr = data->get_DepthMinReliableDistance(
        &nDepthMinReliableDistance);
    if (SUCCEEDED(hr)) hr = data->get_DepthMaxReliableDistance(
        &nDepthMaxReliableDistance);

    if (SUCCEEDED(hr)) {
            if (SUCCEEDED(frameDesc->get_Height(&height)) &&
            SUCCEEDED(frameDesc->get_Width(&width))) {
            depthBuffer = new UINT16[height * width];
            hr = data->CopyFrameDataToArray(height * width, depthBuffer);
            if (SUCCEEDED(hr)) {
                cv::Mat depthMap = cv::Mat(height, width, CV_16U, depthBuffer);
                cv::Mat img0 = cv::Mat::zeros(height, width, CV_8UC1);
                cv::Mat img1;
                double scale = 255.0 / (nDepthMaxReliableDistance - 
                    nDepthMinReliableDistance);
                depthMap.convertTo(img0, CV_8UC1, scale);
                applyColorMap(img0, img1, cv::COLORMAP_JET);
                cv::imshow("Depth Only", img1);
            }
        }
    }
    if (depthBuffer != nullptr) {
        delete[] depthBuffer;
        depthBuffer = nullptr;
    }
    SAFERELEASE(data);
}

int main(int argc, char** argv) {
    HRESULT hr;
    IKinectSensor* kinectSensor = nullptr;     // kinect sensor

    // initialize Kinect Sensor
    hr = GetDefaultKinectSensor(&kinectSensor);
    if (FAILED(hr) || !kinectSensor) {
        std::cout << "ERROR hr=" << hr << "; sensor=" << kinectSensor << std::endl;
        return -1;
    }
    CHECKERROR(kinectSensor->Open());

    // initialize depth frame reader
    IDepthFrameSource* depthFrameSource = nullptr;
    CHECKERROR(kinectSensor->get_DepthFrameSource(&depthFrameSource));
    CHECKERROR(depthFrameSource->OpenReader(&depthFrameReader));
    SAFERELEASE(depthFrameSource);

    while (depthFrameReader) {
        processIncomingData();
        int key = cv::waitKey(10);
        if (key == 'q'){
            break;
        }
    }

    // de-initialize Kinect Sensor
    CHECKERROR(kinectSensor->Close());
    SAFERELEASE(kinectSensor);
    return 0;
}

Results in my messy room:

If we modify the scaling, for example:

                nDepthMaxReliableDistance = 900;
                nDepthMinReliableDistance = 500;
                int i, j;
                for (i = 0; i < height; i++) {
                    for (j = 0; j < width; j++) {
                        UINT16 val = depthMap.at<UINT16>(i,j);
                        val = val - nDepthMinReliableDistance;
                        val = (val > nDepthMaxReliableDistance ? 
                            nDepthMinReliableDistance : val);
                        val = (val < 0 ? 0 : val);
                        depthMap.at<UINT16>(i,j) = val;
                    }
                }

                double scale = 255.0 / (nDepthMaxReliableDistance - 
                    nDepthMinReliableDistance);
                depthMap.convertTo(img0, CV_8UC1, scale);
                applyColorMap(img0, img1, cv::COLORMAP_WINTER);
                cv::imshow("Depth Only", img1);

It may look like this:

That's all :)