example4velodyne.cpp

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "config.h"
#include "config_util.h"
#include "eventlog.h"
#include "lcmtypes_velodyne_t.h"
#include "lcmtypes_pose_t.h"
#include "small_linalg.h"
#include "velodyne.h"

int main(int argc, char **argv)
{
    if(argc < 4) {
        fprintf(stderr, 
                "usage: example4-velodyne <logfile> <start_time> <end time>\n"
                "\n"
                "start_time and end_time are given in seconds from the\n"
                "start of the log file\n");
        return 1;
    }

    lcm_eventlog_t *log = lcm_eventlog_create(argv[1], "r");
    if(!log) {
        fprintf(stderr, "error opening log file\n");
        return 1;
    }

    double start_time = strtod(argv[2], NULL);
    double end_time = strtod(argv[3], NULL);

    Config *config = config_parse_default();
    if(!config) {
        fprintf(stderr, "couldn't find config file\n");
        return 1;
    }

    // load the velodyne sensor calibration
    velodyne_calib_t *vcalib = velodyne_calib_create();

    // read the first timestamp of the log file
    lcm_eventlog_event_t *event = lcm_eventlog_read_next_event(log);
    int64_t first_timestamp = event->timestamp;

    // compute the desired start and end timestamps
    int64_t start_utime = first_timestamp + (int64_t)(start_time * 1000000);
    int64_t end_utime = first_timestamp + (int64_t)(end_time * 1000000);

    lcmtypes_pose_t last_pose;
    memset(&last_pose, 0, sizeof(last_pose));

    while(1) {
        // release the last event
        lcm_eventlog_free_event(event);

        // read an event
        event = lcm_eventlog_read_next_event(log);

        if(!event)
            break;

        // always keep track of the current pose
        if(!strcmp(event->channel, "POSE")) {
            if(last_pose.utime) 
                lcmtypes_pose_t_decode_cleanup(&last_pose);

            lcmtypes_pose_t_decode(event->data, 0, event->datalen, &last_pose);
        }

        // ignore other messages until the desired start time
        if(event->timestamp < start_utime) {
            continue;
        }

        // quit if we're done
        if(event->timestamp >= end_utime) {
            break;
        }

        if(!strcmp(event->channel, "VELODYNE")) {
            // parse the LCM packet into a velodyne data packet.
            lcmtypes_velodyne_t vel;
            lcmtypes_velodyne_t_decode(event->data, 0, event->datalen, 
                    &vel);

            // compute the velodyne-to-local transformation matrix
            // 
            // This is an approximation because we're using the last recorded
            // pose.  A more accurate projection might be to project the
            // vehicle's pose forward based on its last measured velocity.
            double velodyne_to_local[16];
            config_util_sensor_to_local_with_pose (config, "VELODYNE", 
                velodyne_to_local, &last_pose);

            // parse the velodyne data packet
            velodyne_decoder_t vdecoder;
            velodyne_decoder_init(vcalib, &vdecoder, vel.data, vel.datalen);

            // project each sample in the velodyne data packet into the local
            // frame
            velodyne_sample_t vsample;
            while (!velodyne_decoder_next(vcalib, &vdecoder, &vsample)) {
                if (vsample.range < 0.01) {
                    continue;
                }

                double sensor_xyz[4] = { 
                    vsample.xyz[0], vsample.xyz[1], vsample.xyz[2], 1 
                };
                double local_xyz[4];
                matrix_vector_multiply_4x4_4d(velodyne_to_local, 
                        sensor_xyz, local_xyz);

                printf("%f %f %f\n", local_xyz[0], local_xyz[1], local_xyz[2]);
            }

            lcmtypes_velodyne_t_decode_cleanup(&vel);
        }

    }
    lcm_eventlog_free_event(event);

    lcm_eventlog_destroy(log);

    return 0;
}