サーマルカメラのプログラミング

サーマルカメラLepton3.5とUSB接続アダプタPureThermal 2 を手に入れたのでRaspberry Pi4でC言語を使い温度を読み出すプログラムを作成しました。

PureThermal UVC Capture Examplesを参考に作成しました。グラフィックにはEGGX / ProCALLを使用しています。 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <linux/videodev2.h>
#include <libv4l2.h>
#include <eggx.h>

#define CLEAR(x) memset(&(x), 0, sizeof(x))

struct buffer {
    void   *start;
    size_t length;
};

static void xioctl(int fh, int request, void *arg)
{
    int r;

    do {
        r = v4l2_ioctl(fh, request, arg);
    } while (r == -1 && ((errno == EINTR) || (errno == EAGAIN)));

    if (r == -1) {
        fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
        exit(EXIT_FAILURE);
    }
}

double ktoc(double val,int radiometryLowGain) 
{
    if (radiometryLowGain) {
        return (val - 2731.5) / 10.0;   //Lowゲイン
    } else {
        return (val - 27315.0) / 100.0; //Hightゲイン　デフォルト
    }
}

int main(int argc, char **argv)
{
    struct v4l2_format              fmt;
    struct v4l2_buffer              buf;
    struct v4l2_requestbuffers      req;
    enum v4l2_buf_type              type;
    fd_set                          fds;
    struct timeval                  tv;
    int                             r, fd = -1;
    unsigned int                    i, n_buffers;
    char                            *dev_name = "/dev/video0";

    struct buffer                   *buffers;

    fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
    if (fd < 0) {
            perror("Cannot open device");
            exit(EXIT_FAILURE);
    }

    CLEAR(fmt);
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width       = 160;
    fmt.fmt.pix.height      = 120;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_Y16;
    fmt.fmt.pix.field       = V4L2_FIELD_NONE;
    xioctl(fd, VIDIOC_S_FMT, &fmt);
    if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_Y16) {
            printf("Libv4l didn't accept this format. Can't proceed.\n");
            exit(EXIT_FAILURE);
    }
    if ((fmt.fmt.pix.width != 160) || (fmt.fmt.pix.height != 120)) {
            printf("Warning: driver is sending image at %dx%d\n",
                    fmt.fmt.pix.width, fmt.fmt.pix.height);
    }
    CLEAR(req);
    req.count = 2;
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory = V4L2_MEMORY_MMAP;
    xioctl(fd, VIDIOC_REQBUFS, &req);

    buffers = calloc(req.count, sizeof(*buffers));
    for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
        CLEAR(buf);

        buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory      = V4L2_MEMORY_MMAP;
        buf.index       = n_buffers;

        xioctl(fd, VIDIOC_QUERYBUF, &buf);

        buffers[n_buffers].length = buf.length;
        buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
                      PROT_READ | PROT_WRITE, MAP_SHARED,
                      fd, buf.m.offset);
        if (MAP_FAILED == buffers[n_buffers].start) {
            perror("mmap");
            exit(EXIT_FAILURE);
        }
    }

    for (i = 0; i < n_buffers; ++i) {
        CLEAR(buf);
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = i;
        xioctl(fd, VIDIOC_QBUF, &buf);
    }
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    xioctl(fd, VIDIOC_STREAMON, &type);
    int win = gopen(160,120);
    layer(win,0,1);
    gsetnonblock(ENABLE);
    for (;;) {
        do {
            FD_ZERO(&fds);
            FD_SET(fd, &fds);

            /* Timeout. */
            tv.tv_sec = 2;
            tv.tv_usec = 0;

            r = select(fd + 1, &fds, NULL, NULL, &tv);
        } while ((r == -1 && (errno = EINTR)));
        if (r == -1) {
            perror("select");
            return errno;
        }

        CLEAR(buf);
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        xioctl(fd, VIDIOC_DQBUF, &buf);

        for(int y=0;y<120;y++) {
            for(int x=0;x<160;x++) {
                int r,g,b;
                unsigned int temp = *((uint16_t *)(buffers[buf.index].start+(160*y+x)*2)) ;
                double t = ktoc(temp,0);//温度に変換
                if(t<20) t=20;  // 20℃〜40℃の間のみ可視化
                if(t>40) t=40;
                if(makecolor(DS9_B,20,40,t,&r,&g,&b)!=0) {
                    fprintf(stderr,"makecolor() over flow.\n");
                    exit(1);
                }
                newrgbcolor(win,r,g,b);
                pset(win,x,120-1 - y);
            }
        }
        copylayer(win,1,0);
        xioctl(fd, VIDIOC_QBUF, &buf);
        if(ggetch()>0) break;
    }

    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    xioctl(fd, VIDIOC_STREAMOFF, &type);
    for (i = 0; i < n_buffers; ++i) {
        v4l2_munmap(buffers[i].start, buffers[i].length);
    }
    v4l2_close(fd);
    gclose(win);
    return 0;
}

コンパイル

$ sudo apt install libv4l-dev
$ gcc -o view view.c -lv4l2 -leggx -lX11 -lm

 

参考

PureThermal UVC Capture Examples

2.9.1. Packed RGB formats

Using SuperResolution with a Lepton 3.5 PureThermal 2