laser_geometry.py

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"""
Copyright (c) 2014, Enrique Fernandez
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the Willow Garage, Inc. nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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"""

import rospy
from sensor_msgs.msg import PointCloud2
import sensor_msgs.point_cloud2 as pc2

import numpy as np

class LaserProjection:
    """
    A class to Project Laser Scan

    This calls will project laser scans into point clouds. It caches
    unit vectors between runs (provided the angular resolution of
    your scanner is not changing) to avoid excess computation.

    By default all range values less thatn the scanner min_range,
    greater than the scanner max_range are removed from the generated
    point cloud, as these are assumed to be invalid.

    If it is important to preserve a mapping between the index of
    range values and points in the cloud, the recommended approach is to
    pre-filter your laser scan message to meet the requirement that all
    ranges are between min and max_range.

    The generate PointClouds have a number of channels which can be enabled
    through the use of ChannelOption.
    - ChannelOption.INTENSITY - Create a channel named "intensities" with the
    intensity of the return for each point.
    - ChannelOption.INDEX     - Create a channel named "index" containing the
    index from the original array for each point.
    - ChannelOption.DISTANCE  - Create a channel named "distance" containing
    the distance from the laser to each point.
    - ChannelOption.TIMESTAMP - Create a channel named "stamps" containing the
    specific timestamp at which each point was measured.
    """

    LASER_SCAN_INVALID   = -1.0
    LASER_SCAN_MIN_RANGE = -2.0
    LASER_SCAN_MAX_RANGE = -3.0

    class ChannelOption:
        NONE      = 0x00 # Enable no channels
        INTENSITY = 0x01 # Enable "intensities" channel
        INDEX     = 0x02 # Enable "index"       channel
        DISTANCE  = 0x04 # Enable "distances"   channel
        TIMESTAMP = 0x08 # Enable "stamps"      channel
        VIEWPOINT = 0x10 # Enable "viewpoint"   channel
        DEFAULT   = (INTENSITY | INDEX)

    def __init__(self):
        self.__angle_min = 0.0
        self.__angle_max = 0.0

        self.__cos_sin_map = np.array([[]])

    def projectLaser(self, scan_in,
            range_cutoff=-1.0, channel_options=ChannelOption.DEFAULT):
        """
        Project a sensor_msgs::LaserScan into a sensor_msgs::PointCloud2.

        Project a single laser scan from a linear array into a 3D
        point cloud. The generated cloud will be in the same frame
        as the original laser scan.

        Keyword arguments:
        scan_in -- The input laser scan.
        range_cutoff -- An additional range cutoff which can be
            applied which is more limiting than max_range in the scan
            (default -1.0).
        channel_options -- An OR'd set of channels to include.
        """
        return self.__projectLaser(scan_in, range_cutoff, channel_options)

    def __projectLaser(self, scan_in, range_cutoff, channel_options):
        N = len(scan_in.ranges)

        ranges = np.array(scan_in.ranges)

        if (self.__cos_sin_map.shape[1] != N or
            self.__angle_min != scan_in.angle_min or
            self.__angle_max != scan_in.angle_max):
            rospy.logdebug("No precomputed map given. Computing one.")

            self.__angle_min = scan_in.angle_min
            self.__angle_max = scan_in.angle_max
            
            angles = scan_in.angle_min + np.arange(N) * scan_in.angle_increment
            self.__cos_sin_map = np.array([np.cos(angles), np.sin(angles)])

        output = ranges * self.__cos_sin_map

        # Set the output cloud accordingly
        cloud_out = PointCloud2()

        fields = [pc2.PointField() for _ in range(3)]

        fields[0].name = "x"
        fields[0].offset = 0
        fields[0].datatype = pc2.PointField.FLOAT32
        fields[0].count = 1

        fields[1].name = "y"
        fields[1].offset = 4
        fields[1].datatype = pc2.PointField.FLOAT32
        fields[1].count = 1

        fields[2].name = "z"
        fields[2].offset = 8
        fields[2].datatype = pc2.PointField.FLOAT32
        fields[2].count = 1

        idx_intensity = idx_index = idx_distance =  idx_timestamp = -1
        idx_vpx = idx_vpy = idx_vpz = -1

        offset = 12

        if (channel_options & self.ChannelOption.INTENSITY and
            len(scan_in.intensities) > 0):
            field_size = len(fields)
            fields.append(pc2.PointField())
            fields[field_size].name = "intensity"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_intensity = field_size

        if channel_options & self.ChannelOption.INDEX:
            field_size = len(fields)
            fields.append(pc2.PointField())
            fields[field_size].name = "index"
            fields[field_size].datatype = pc2.PointField.INT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_index = field_size

        if channel_options & self.ChannelOption.DISTANCE:
            field_size = len(fields)
            fields.append(pc2.PointField())
            fields[field_size].name = "distances"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_distance = field_size

        if channel_options & self.ChannelOption.TIMESTAMP:
            field_size = len(fields)
            fields.append(pc2.PointField())
            fields[field_size].name = "stamps"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_timestamp = field_size

        if channel_options & self.ChannelOption.VIEWPOINT:
            field_size = len(fields)
            fields.extend([pc2.PointField() for _ in range(3)])
            fields[field_size].name = "vp_x"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_vpx = field_size
            field_size += 1

            fields[field_size].name = "vp_y"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_vpy = field_size
            field_size += 1

            fields[field_size].name = "vp_z"
            fields[field_size].datatype = pc2.PointField.FLOAT32
            fields[field_size].offset = offset
            fields[field_size].count = 1
            offset += 4
            idx_vpz = field_size

        if range_cutoff < 0:
            range_cutoff = scan_in.range_max
        else:
            range_cutoff = min(range_cutoff, scan_in.range_max)

        points = []
        for i in range(N):
            ri = scan_in.ranges[i]
            if ri < range_cutoff and ri >= scan_in.range_min:
                point = output[:, i].tolist()
                point.append(0)

                if idx_intensity != -1:
                    point.append(scan_in.intensities[i])

                if idx_index != -1:
                    point.append(i)

                if idx_distance != -1:
                    point.append(scan_in.ranges[i])

                if idx_timestamp != -1:
                    point.append(i * scan_in.time_increment)

                if idx_vpx != -1 and idx_vpy != -1 and idx_vpz != -1:
                    point.extend([0 for _ in range(3)])

                points.append(point)

        cloud_out = pc2.create_cloud(scan_in.header, fields, points)

        return cloud_out