Folder [Workflow] contains the source code for the workflow, with its contents described below:

Table of Contents

• Overview
• File Structure
• Requirements
• Usage Instructions
• Example
• License
• Contact

Overview

This repository contains the input data and source code for extracting ungulate trails in the marsh area of Oostvaardersplassen using 3D point clouds obtained from airborne laser scanning, specifically AHN4 point clouds. The workflow consists of four major steps:

1. Pre-processing
2. Near-terrain filtering
3. Digital Terrain Model (DTM) generation
4. Trail extraction

File Structure

Workflow/
│
├── 0_dependencies/          # Required dependencies, including LAStools, PointCloud data structures, and nanoflann for neighborhood searching.
│
├── 1_clipping/              # Source code for clipping the original point clouds into smaller tiles.
│
├── 2_near_terrain_filtering/ # Filtering near-terrain and vegetation points from the re-tiled point clouds.
│
├── 3_dtm_generation/        # Generation of Digital Terrain Models (DTMs) from the re-tiled point clouds.
│
└── 4_trail_extraction/      # Extraction of trails from the generated DTMs.

Requirements

C++ Code

The C++ scripts in this repository depend on LAStools for reading point cloud data in LAS/LAZ formats.

To use the scripts, a C++ compiler such as g++, gcc, msvc, or clang++ must be installed.

Usage Instructions

There are three ways to build the project:

• Option 1: Using CMake to generate Makefiles and then running make (Linux/macOS).

  • On Linux or macOS:

    cd path-to-root-dir-of-project
    mkdir release && cd release
    cmake -DCMAKE_BUILD_TYPE=release ..
    make

  • On Windows with Microsoft Visual Studio, use the x64 Native Tools Command Prompt for VS XXXX (do not use the x86 version). Then run:

    cd path-to-root-dir-of-project
    mkdir Release && cd Release
    cmake -G "NMake Makefiles" -DCMAKE_BUILD_TYPE=Release ..
    nmake

• Option 2: Using an IDE that supports CMakeLists.txt.
  Open the CMakeLists.txt file in the root directory of the project with an IDE such as CLion or QtCreator. Then, build the project.

  Note for Windows users: Ensure that your IDE is set to x64.

• Option 3: Using CMake-GUI to generate project files for an IDE.
  Load the generated project into your IDE and build it.

  Note for Windows users: Ensure that your IDE is set to x64.

Example

Example Usage of the C++ Module [1_clipping]

#include "clip_las.h"
#include "../shapelib/shapelib/shapefil.h"

#include <iostream>
#include <vector>

int main(int argc, char** argv)
{
    // Set the file and folder paths.
    std::string shpFilePath = "Path\\to\\shapefile.shp";
    std::string lasFilePath = "Path\\to\\Input\\LAS\\Files\\";
    std::string lasFileOutputPath = "Path\\to\\Output\\LAS\\Files\\";

    mm::ClipLas* clip = new mm::ClipLas;
    
    clip->ListFilesInDirectory(lasFilePath);
    clip->setOutputLasPath(lasFileOutputPath);
    clip->setShpFilePath(shpFilePath);
    clip->readShpFile2();
    clip->getPositivePolygons(); 
    clip->setLasFileDirName(lasFilePath);
    clip->runClipping3(); 

    if (clip)
    {
        delete clip;
        clip = nullptr;
    }
    return 0;
}

License

This project is licensed under the MIT License.

Contact

For any suggestions or bug reports, please contact:

Jinhu Wang
📧 jinhu.wang (at) hotmail (dot) com