[filters] Revise filters which might be out of date due to `functor_filter`

[kunaltyagi]

Is your feature request related to a problem? Please describe.

Some older implementations of filters (at least PassThrough and ConditionalRemoval) are very slow compared to what can be achieved by FunctorFilter (introduced by #3890)

Context

Source Code

#include <benchmark/benchmark.h>
#include <pcl/filters/conditional_removal.h>
#include <pcl/filters/functor_filter.h>
#include <pcl/filters/passthrough.h>
#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl/types.h>

#include <functional>
#include <random>

struct PointCloudFixture : public benchmark::Fixture
{
    void SetUp(const ::benchmark::State& state)
    {
        cloud = pcl::make_shared<pcl::PointCloud<pcl::PointXYZ>>();
        cloud->resize(state.range(0));
        for (auto& pt : *cloud) {
            pt = pcl::PointXYZ{0., 0., 0.};
        }
    }
    pcl::shared_ptr<pcl::PointCloud<pcl::PointXYZ>> cloud;
};

BENCHMARK_DEFINE_F(PointCloudFixture, FunctionTest)(benchmark::State& st)
{
    const auto lambda = [](const pcl::PointCloud<pcl::PointXYZ>& cloud,
                           pcl::index_t idx) {
        const auto pt = cloud[idx];
        return (pt.getArray3fMap() < 10).all() &&
               (pt.getArray3fMap() > -10).all();
    };

    const std::function<bool(const pcl::PointCloud<pcl::PointXYZ>&,
                             pcl::index_t)>
        functor = lambda;
    pcl::FunctorFilter<pcl::PointXYZ, decltype(functor)> filter{functor};
    filter.setInputCloud(cloud);

    auto out_cloud = pcl::make_shared<pcl::PointCloud<pcl::PointXYZ>>();
    for (auto _ : st) {
        filter.filter(*out_cloud);
    }
}

BENCHMARK_DEFINE_F(PointCloudFixture, LambdaTest)(benchmark::State& st)
{
    const auto lambda = [](const pcl::PointCloud<pcl::PointXYZ>& cloud,
                           pcl::index_t idx) {
        const auto pt = cloud[idx];
        return (pt.getArray3fMap() < 10).all() &&
               (pt.getArray3fMap() > -10).all();
    };

    pcl::FunctorFilter<pcl::PointXYZ, decltype(lambda)> filter{lambda};
    filter.setInputCloud(cloud);

    auto out_cloud = pcl::make_shared<pcl::PointCloud<pcl::PointXYZ>>();
    for (auto _ : st) {
        filter.filter(*out_cloud);
    }
}

BENCHMARK_DEFINE_F(PointCloudFixture, PassthroughTest)(benchmark::State& st)
{
    pcl::PassThrough<pcl::PointXYZ> filter_x, filter_y, filter_z;
    auto out_cloud = pcl::make_shared<pcl::PointCloud<pcl::PointXYZ>>();

    filter_x.setFilterLimits(-10., 10.);
    filter_x.setInputCloud(cloud);
    filter_x.setFilterFieldName("x");
    filter_y.setFilterLimits(-10., 10.);

    filter_y.setInputCloud(out_cloud);
    filter_y.setFilterFieldName("y");
    filter_z.setFilterLimits(-10., 10.);
    filter_z.setInputCloud(out_cloud);
    filter_z.setFilterFieldName("z");

    for (auto _ : st) {
        filter_x.filter(*out_cloud);
        filter_y.filter(*out_cloud);
        filter_z.filter(*out_cloud);
    }
}

BENCHMARK_DEFINE_F(PointCloudFixture, ConditionalTest)(benchmark::State& st)
{
    pcl::ConditionalRemoval<pcl::PointXYZ> filter;
    auto box_cond = pcl::make_shared<pcl::ConditionAnd<pcl::PointXYZ>>();
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "x", pcl::ComparisonOps::GT, -10.0));
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "x", pcl::ComparisonOps::LT, 10.0));
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "y", pcl::ComparisonOps::GT, -10.0));
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "y", pcl::ComparisonOps::LT, 10.0));
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "z", pcl::ComparisonOps::GT, -10.0));
    box_cond->addComparison(
        pcl::make_shared<pcl::FieldComparison<pcl::PointXYZ>>(
            "z", pcl::ComparisonOps::LT, 10.0));
    filter.setCondition(box_cond);
    filter.setInputCloud(cloud);

    auto out_cloud = pcl::make_shared<pcl::PointCloud<pcl::PointXYZ>>();

    for (auto _ : st) {
        filter.filter(*out_cloud);
    }
}

BENCHMARK_REGISTER_F(PointCloudFixture, FunctionTest)->Range(8, 8 << 10);
BENCHMARK_REGISTER_F(PointCloudFixture, LambdaTest)->Range(8, 8 << 10);
BENCHMARK_REGISTER_F(PointCloudFixture, PassthroughTest)->Range(8, 8 << 10);
BENCHMARK_REGISTER_F(PointCloudFixture, ConditionalTest)->Range(8, 8 << 10);

BENCHMARK_MAIN();

Run on (8 X 1700 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB (x4)
  L1 Instruction 32 KiB (x4)
  L2 Unified 256 KiB (x4)
  L3 Unified 8192 KiB (x1)
Load Average: 2.74, 3.08, 3.17
---------------------------------------------------------------------------------
Benchmark                                       Time             CPU   Iterations
---------------------------------------------------------------------------------
PointCloudFixture/FunctionTest/8              131 ns          130 ns      4159808
PointCloudFixture/FunctionTest/64             501 ns          490 ns      1121417
PointCloudFixture/FunctionTest/512           2428 ns         2382 ns       293105
PointCloudFixture/FunctionTest/4096         18383 ns        18337 ns        37591
PointCloudFixture/FunctionTest/8192         36809 ns        36739 ns        19173
PointCloudFixture/LambdaTest/8                110 ns          110 ns      6064439
PointCloudFixture/LambdaTest/64               337 ns          336 ns      2080516
PointCloudFixture/LambdaTest/512             1580 ns         1577 ns       414660
PointCloudFixture/LambdaTest/4096           12228 ns        12196 ns        55128
PointCloudFixture/LambdaTest/8192           25384 ns        25313 ns        27361
PointCloudFixture/PassthroughTest/8          2042 ns         2038 ns       334526
PointCloudFixture/PassthroughTest/64         2631 ns         2623 ns       266375
PointCloudFixture/PassthroughTest/512        8524 ns         8505 ns        81159
PointCloudFixture/PassthroughTest/4096      57221 ns        57036 ns        10940
PointCloudFixture/PassthroughTest/8192     111504 ns       111357 ns         5865
PointCloudFixture/ConditionalTest/8           291 ns          290 ns      2404366
PointCloudFixture/ConditionalTest/64         2150 ns         2145 ns       330248
PointCloudFixture/ConditionalTest/512       17053 ns        17020 ns        41152
PointCloudFixture/ConditionalTest/4096     134140 ns       133865 ns         5070
PointCloudFixture/ConditionalTest/8192     271490 ns       270909 ns         2580

Expected behavior

PCL should not offer duplicate features, specially when the one that is easier to use, search and stumble upon also provides much worse performance. In this case,

• Using lambda is 1.45x faster than std::function 😄
• Using lambda is 4.39x faster than PassThrough 😱
• Using lambda is 10.70x faster than ConditionalRemoval 🙀

Describe the solution you'd like

For simple filters (such as PassThrough and ConditionalRemoval, etc.), we should either

• reimplement them (after benchmarking) OR
• deprecate them

This allows downstream users to get performance improvements (or notifications about a faster way) and also prevents new users from misusing the library. Depending on the decision, we would need to modify the docs and highlight the new feature

[stale[bot]]

Marking this as stale due to 30 days of inactivity. It will be closed in 7 days if no further activity occurs.

[ark-tik]

Hi, can I work on this issue? I can see a merged and an open branch referring to this issue right now, so if this performance improvement is still desirable I'd like to help with this.

[mvieth]

Hi, can I work on this issue? I can see a merged and an open branch referring to this issue right now, so if this performance improvement is still desirable I'd like to help with this.

Great that you want to work on this, however I am not sure how to proceed here. I think we first have to review the open (draft) pull request above, and see whether we have to make any design decisions. Until then, maybe you find another open issue that interests you?