Introduce RangeDataCollator (#975)

Synchronizes and merge-sorts TimedPointCloudData by per-point timestamps from
multiple sensors.

[RFC=0017](https://github.com/googlecartographer/rfcs/blob/master/text/0017-synchronize-points.md)
master
gaschler 2018-03-13 11:08:01 +01:00 committed by Wally B. Feed
parent 976736051c
commit 1187480fe6
4 changed files with 329 additions and 0 deletions

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/*
* Copyright 2018 The Cartographer Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "cartographer/mapping/internal/range_data_collator.h"
#include <memory>
#include "cartographer/common/make_unique.h"
#include "cartographer/mapping/local_slam_result_data.h"
#include "glog/logging.h"
namespace cartographer {
namespace mapping {
sensor::TimedPointCloudOriginData RangeDataCollator::AddRangeData(
const std::string& sensor_id,
const sensor::TimedPointCloudData& timed_point_cloud_data) {
CHECK(expected_sensor_ids_.count(sensor_id) != 0);
// TODO(gaschler): These two cases can probably be one.
if (id_to_pending_data_.count(sensor_id) != 0) {
current_start_ = current_end_;
// When we have two messages of the same sensor, move forward the older of
// the two (do not send out current).
current_end_ = id_to_pending_data_.at(sensor_id).time;
auto result = CropAndMerge();
id_to_pending_data_.emplace(sensor_id, timed_point_cloud_data);
return result;
}
id_to_pending_data_.emplace(sensor_id, timed_point_cloud_data);
if (expected_sensor_ids_.size() != id_to_pending_data_.size()) {
return {};
}
current_start_ = current_end_;
// We have messages from all sensors, move forward to oldest.
common::Time oldest_timestamp = common::Time::max();
for (const auto& pair : id_to_pending_data_) {
oldest_timestamp = std::min(oldest_timestamp, pair.second.time);
}
current_end_ = oldest_timestamp;
return CropAndMerge();
}
sensor::TimedPointCloudOriginData RangeDataCollator::CropAndMerge() {
sensor::TimedPointCloudOriginData result{current_end_, {}, {}};
bool warned_for_dropped_points = false;
for (auto it = id_to_pending_data_.begin();
it != id_to_pending_data_.end();) {
sensor::TimedPointCloudData& data = it->second;
sensor::TimedPointCloud& ranges = it->second.ranges;
auto overlap_begin = ranges.begin();
while (overlap_begin < ranges.end() &&
data.time + common::FromSeconds((*overlap_begin)[3]) <
current_start_) {
++overlap_begin;
}
auto overlap_end = overlap_begin;
while (overlap_end < ranges.end() &&
data.time + common::FromSeconds((*overlap_end)[3]) <= current_end_) {
++overlap_end;
}
if (ranges.begin() < overlap_begin && !warned_for_dropped_points) {
LOG(WARNING) << "Dropped " << std::distance(ranges.begin(), overlap_begin)
<< " earlier points.";
warned_for_dropped_points = true;
}
// Copy overlapping range.
if (overlap_begin < overlap_end) {
std::size_t origin_index = result.origins.size();
result.origins.push_back(data.origin);
double time_correction = common::ToSeconds(data.time - current_end_);
for (auto overlap_it = overlap_begin; overlap_it != overlap_end;
++overlap_it) {
sensor::TimedPointCloudOriginData::RangeMeasurement point{*overlap_it,
origin_index};
// current_end_ + point_time[3]_after == in_timestamp +
// point_time[3]_before
point.point_time[3] += time_correction;
result.ranges.push_back(point);
}
}
// Drop buffered points until overlap_end.
if (overlap_end == ranges.begin()) {
++it;
} else if (overlap_end == ranges.end()) {
it = id_to_pending_data_.erase(it);
} else {
data = sensor::TimedPointCloudData{
data.time, data.origin,
sensor::TimedPointCloud(overlap_end, ranges.end())};
++it;
}
}
std::sort(result.ranges.begin(), result.ranges.end(),
[](const sensor::TimedPointCloudOriginData::RangeMeasurement& a,
const sensor::TimedPointCloudOriginData::RangeMeasurement& b) {
return a.point_time[3] < b.point_time[3];
});
return result;
}
} // namespace mapping
} // namespace cartographer

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/*
* Copyright 2018 The Cartographer Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef CARTOGRAPHER_MAPPING_INTERNAL_RANGE_DATA_COLLATOR_H_
#define CARTOGRAPHER_MAPPING_INTERNAL_RANGE_DATA_COLLATOR_H_
#include <memory>
#include "cartographer/common/make_unique.h"
#include "cartographer/sensor/timed_point_cloud_data.h"
namespace cartographer {
namespace mapping {
// Synchronizes TimedPointCloudData from different sensors. Input needs only be
// monotonous in 'TimedPointCloudData::time', output is monotonous in per-point
// timing. Up to one message per sensor is buffered, so a delay of the period of
// the slowest sensor may be introduced, which can be alleviated by passing
// subdivisions.
class RangeDataCollator {
public:
explicit RangeDataCollator(
const std::vector<std::string>& expected_range_sensor_ids)
: expected_sensor_ids_(expected_range_sensor_ids.begin(),
expected_range_sensor_ids.end()) {}
sensor::TimedPointCloudOriginData AddRangeData(
const std::string& sensor_id,
const sensor::TimedPointCloudData& timed_point_cloud_data);
private:
sensor::TimedPointCloudOriginData CropAndMerge();
const std::set<std::string> expected_sensor_ids_;
// Store at most one message for each sensor.
std::map<std::string, sensor::TimedPointCloudData> id_to_pending_data_;
common::Time current_start_ = common::Time::min();
common::Time current_end_ = common::Time::min();
};
} // namespace mapping
} // namespace cartographer
#endif // CARTOGRAPHER_MAPPING_INTERNAL_RANGE_DATA_COLLATOR_H_

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/*
* Copyright 2018 The Cartographer Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "cartographer/mapping/internal/range_data_collator.h"
#include "cartographer/common/time.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
namespace cartographer {
namespace mapping {
namespace {
const int kNumSamples = 10;
sensor::TimedPointCloudData CreateFakeRangeData(int from, int to) {
double duration = common::ToSeconds(common::FromUniversal(to) -
common::FromUniversal(from));
sensor::TimedPointCloudData result{common::FromUniversal(to),
Eigen::Vector3f(0., 1., 2.),
sensor::TimedPointCloud(kNumSamples)};
for (int i = 0; i < kNumSamples; ++i) {
double fraction = static_cast<double>(i) / (kNumSamples - 1);
double relative_time = (1.f - fraction) * -duration;
result.ranges[i] = Eigen::Vector4f(1., 2., 3., relative_time);
}
return result;
}
bool ArePointTimestampsSorted(const sensor::TimedPointCloudOriginData& data) {
std::vector<float> timestamps;
timestamps.reserve(data.ranges.size());
for (const auto& range : data.ranges) {
timestamps.push_back(range.point_time[3]);
}
return std::is_sorted(timestamps.begin(), timestamps.end());
}
TEST(RangeDataCollatorTest, SingleSensor) {
const std::string sensor_id = "single_sensor";
RangeDataCollator collator({sensor_id});
auto output_0 =
collator.AddRangeData(sensor_id, CreateFakeRangeData(200, 300));
EXPECT_EQ(common::ToUniversal(output_0.time), 300);
EXPECT_EQ(output_0.origins.size(), 1);
EXPECT_EQ(output_0.ranges.size(), kNumSamples);
EXPECT_TRUE(ArePointTimestampsSorted(output_0));
auto output_1 =
collator.AddRangeData(sensor_id, CreateFakeRangeData(300, 500));
EXPECT_EQ(common::ToUniversal(output_1.time), 500);
EXPECT_EQ(output_1.origins.size(), 1);
ASSERT_EQ(output_1.ranges.size(), kNumSamples);
EXPECT_TRUE(ArePointTimestampsSorted(output_1));
EXPECT_NEAR(common::ToUniversal(
output_1.time +
common::FromSeconds(output_1.ranges[0].point_time[3])),
300, 2);
auto output_2 =
collator.AddRangeData(sensor_id, CreateFakeRangeData(-1000, 510));
EXPECT_EQ(common::ToUniversal(output_2.time), 510);
EXPECT_EQ(output_2.origins.size(), 1);
EXPECT_EQ(output_2.ranges.size(), 1);
EXPECT_EQ(output_2.ranges[0].point_time[3], 0.f);
EXPECT_TRUE(ArePointTimestampsSorted(output_2));
}
TEST(RangeDataCollatorTest, TwoSensors) {
const std::string sensor_0 = "sensor_0";
const std::string sensor_1 = "sensor_1";
RangeDataCollator collator({sensor_0, sensor_1});
auto output_0 =
collator.AddRangeData(sensor_0, CreateFakeRangeData(200, 300));
EXPECT_EQ(output_0.ranges.size(), 0);
auto output_1 =
collator.AddRangeData(sensor_1, CreateFakeRangeData(-1000, 310));
EXPECT_EQ(output_1.origins.size(), 2);
EXPECT_EQ(common::ToUniversal(output_1.time), 300);
ASSERT_EQ(output_1.ranges.size(), 2 * kNumSamples - 1);
EXPECT_NEAR(common::ToUniversal(
output_1.time +
common::FromSeconds(output_1.ranges[0].point_time[3])),
-1000, 2);
EXPECT_EQ(output_1.ranges.back().point_time[3], 0.f);
EXPECT_TRUE(ArePointTimestampsSorted(output_1));
auto output_2 =
collator.AddRangeData(sensor_0, CreateFakeRangeData(300, 500));
EXPECT_EQ(output_2.origins.size(), 2);
EXPECT_EQ(common::ToUniversal(output_2.time), 310);
ASSERT_EQ(output_2.ranges.size(), 2);
EXPECT_NEAR(common::ToUniversal(
output_2.time +
common::FromSeconds(output_2.ranges[0].point_time[3])),
300, 2);
EXPECT_EQ(output_2.ranges.back().point_time[3], 0.f);
EXPECT_TRUE(ArePointTimestampsSorted(output_2));
// Sending the same sensor will flush everything before.
auto output_3 =
collator.AddRangeData(sensor_0, CreateFakeRangeData(600, 700));
EXPECT_EQ(common::ToUniversal(output_3.time), 500);
EXPECT_EQ(
output_1.ranges.size() + output_2.ranges.size() + output_3.ranges.size(),
3 * kNumSamples);
EXPECT_EQ(output_3.ranges.back().point_time[3], 0.f);
EXPECT_TRUE(ArePointTimestampsSorted(output_3));
}
TEST(RangeDataCollatorTest, ThreeSensors) {
const std::string sensor_0 = "sensor_0";
const std::string sensor_1 = "sensor_1";
const std::string sensor_2 = "sensor_2";
RangeDataCollator collator({sensor_0, sensor_1, sensor_2});
auto output_0 =
collator.AddRangeData(sensor_0, CreateFakeRangeData(100, 200));
EXPECT_EQ(output_0.ranges.size(), 0);
auto output_1 =
collator.AddRangeData(sensor_1, CreateFakeRangeData(199, 250));
EXPECT_EQ(output_1.ranges.size(), 0);
auto output_2 =
collator.AddRangeData(sensor_2, CreateFakeRangeData(210, 300));
EXPECT_EQ(output_2.ranges.size(), kNumSamples + 1);
EXPECT_TRUE(ArePointTimestampsSorted(output_2));
auto output_3 =
collator.AddRangeData(sensor_2, CreateFakeRangeData(400, 500));
EXPECT_EQ(output_2.ranges.size() + output_3.ranges.size(), 3 * kNumSamples);
EXPECT_TRUE(ArePointTimestampsSorted(output_3));
}
} // namespace
} // namespace mapping
} // namespace cartographer

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@ -30,6 +30,16 @@ struct TimedPointCloudData {
sensor::TimedPointCloud ranges; sensor::TimedPointCloud ranges;
}; };
struct TimedPointCloudOriginData {
struct RangeMeasurement {
Eigen::Vector4f point_time;
size_t origin_index;
};
common::Time time;
std::vector<Eigen::Vector3f> origins;
std::vector<RangeMeasurement> ranges;
};
// Converts 'timed_point_cloud_data' to a proto::TimedPointCloudData. // Converts 'timed_point_cloud_data' to a proto::TimedPointCloudData.
proto::TimedPointCloudData ToProto( proto::TimedPointCloudData ToProto(
const TimedPointCloudData& timed_point_cloud_data); const TimedPointCloudData& timed_point_cloud_data);