Add artificial translation example

examples/CMakeLists.txt

@@ -2,12 +2,16 @@ project(cpd-examples CXX)
 cmake_minimum_required(VERSION 2.8.12)
 
 find_package(Cpd REQUIRED)
+find_package(PDAL)
 
 function(cpd_example name)
     set(target ${name}-example)
     add_executable(${target} ${name}.cpp)
     set_target_properties(${target} PROPERTIES OUTPUT_NAME ${name})
-    target_link_libraries(${target} PRIVATE Cpd::Library-C++)
+    target_link_libraries(${target} PRIVATE Cpd::Library-C++ ${ARGN})
 endfunction()
 
 cpd_example(rigid)
+if(PDAL_FOUND)
+    cpd_example(artificial-displacement pdalcpp)
+endif()

examples/artificial-displacement.cpp

@@ -0,0 +1,70 @@
+/// Reads a point cloud, applies an artifical translation, then recovers it.
+///
+/// This example uses [PDAL](http://www.pdal.io/) to read a point cloud file.
+/// The points are then translated, and the translation is recovered with rigid
+/// CPD.
+/// This examples demonstrates configuring the runner, comparer, and
+/// transformation.
+
+#include <cpd/comparer.hpp>
+#include <cpd/logging.hpp>
+#include <cpd/matrix.hpp>
+#include <cpd/rigid.hpp>
+#include <cpd/runner.hpp>
+#include <cpd/vendor/spdlog/spdlog.h>
+#include <iostream>
+#include <pdal/EigenUtils.hpp>
+#include <pdal/Options.hpp>
+#include <pdal/Stage.hpp>
+#include <pdal/StageFactory.hpp>
+
+cpd::Matrix read_cropped_matrix(const std::string& infile) {
+    pdal::StageFactory factory;
+
+    pdal::Stage* reader(factory.createStage(factory.inferReaderDriver(infile)));
+    pdal::Options reader_options;
+    reader_options.add("filename", infile);
+    reader->setOptions(reader_options);
+
+    pdal::PointTable table;
+    reader->prepare(table);
+    pdal::PointViewSet viewSet = reader->execute(table);
+    return pdal::eigen::pointViewToEigen(**viewSet.begin());
+}
+
+cpd::Rigid::Result recover_translation(const cpd::Matrix& fixed,
+                                       const Eigen::Vector3d& translation) {
+    assert(fixed.rows() != 0);
+    cpd::Matrix moving =
+        fixed + translation.transpose().replicate(fixed.rows(), 1);
+    cpd::FgtComparer comparer;
+    comparer.method(cpd::FgtMethod::DirectTree);
+    cpd::Rigid rigid;
+    rigid.scale(false);
+    cpd::Runner<cpd::Rigid, cpd::FgtComparer> runner(rigid, comparer);
+    runner.sigma2(0.2);
+    return runner.run(moving, fixed);
+}
+
+int main(int argc, char** argv) {
+    if (argc != 6) {
+        std::cout << "ERROR: Invalid number of arguments" << std::endl;
+        std::cout
+            << "USAGE: artificial-displacement <infile> <x> <y> <z> <outfile>"
+            << std::endl;
+        return 1;
+    }
+    auto logger = spdlog::stdout_logger_mt(cpd::LOGGER_NAME);
+    std::string infile = argv[1];
+    double x_translation = std::stod(argv[2]);
+    double y_translation = std::stod(argv[3]);
+    double z_translation = std::stod(argv[4]);
+    std::string outfile = argv[5];
+    cpd::Matrix matrix = read_cropped_matrix(infile);
+    Eigen::Vector3d translation(x_translation, y_translation, z_translation);
+    cpd::Rigid::Result result = recover_translation(matrix, translation);
+    std::ofstream ofstream(outfile);
+    ofstream << result << std::endl;
+    ofstream.close();
+    return 0;
+}

examples/rigid.cpp

@@ -1,3 +1,5 @@
+/// Computes the rigid transformation between two text files.
+
 #include <iostream>
 
 #include <cpd/logging.hpp>