Fix lookuptable

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "extern/argh"]
+	path = extern/argh
+	url = https://github.com/adishavit/argh.git

CMakeLists.txt

@@ -1,15 +1,22 @@
+cmake_minimum_required(VERSION 3.20)
+
 project(
   contour-creator
   LANGUAGES CXX)    
   
-find_package(GDAL CONFIG REQUIRED)
-
 add_executable(${PROJECT_NAME}
 	src/HeightMap.cpp src/CellMap.cpp src/main.cpp
 )
+
+# Argh is a simple argrument parser
+add_subdirectory(extern/argh)
+target_link_libraries(${PROJECT_NAME} PRIVATE argh)
+
+# Gdal is used for geodata IO
+find_package(GDAL CONFIG REQUIRED)
+target_link_libraries(${PROJECT_NAME} PRIVATE GDAL::GDAL)
+
 find_package(OpenMP)
 if(OpenMP_CXX_FOUND)
     target_link_libraries(${PROJECT_NAME} PUBLIC OpenMP::OpenMP_CXX)
-endif()
-
-target_link_libraries(${PROJECT_NAME} GDAL::GDAL)
+endif()

build&run.sh

@@ -3,4 +3,4 @@ rm -rf build
 mkdir build
 cmake -DCMAKE_BUILD_TYPE=Debug -B build
 cmake --build build --parallel 
-build/contour-creator 'example_files/crop.tif'
+build/contour-creator --interval=1 --blur example_files/crop.tif

documentation/slides.md

@@ -5,16 +5,31 @@ author:
 - Trygve og Esther
 
 ---
-# What are contours
 
-# Output of our program
-pretty pictures
+# Output of our program:
+![Contour map of Ås](kurver_ås.png)
+
+# Marching squares
+![By Nicoguaro; Adroitwhiz - File:Marching_squares_algorithm.svg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=143418710](ms_wikipedia.svg)
 
 # The logical flow of our program
-flowchart
-
-# GDAL
-What is it?
+```cpp
+int main(int argc, const char* argv[])
+{
+    const char* filepath = argv[1];
+    HeightMap map(filepath); 
+    map.blur(0.8)
+    auto lines = create_lines(&map, 5);
+    write_output_file(cellmaps, "out.geojson", &map);
+}
+```
 
 # Performance
-show the benchmarks
+|                    |       Time         |
+|--------------------|--------------------|
+|  12 threads        |     41s            |
+|   1 thread         |     116s           |
+
+
+# Problems we encountered
+

src/CellMap.cpp

@@ -4,13 +4,13 @@
 #include "contour_creator.hh"
 
 
-CellMap::CellMap(int width, int height, uint8_t* cells, OGRSpatialReference reference_system)
+CellMap::CellMap(int width, int height, uint8_t* cells, OGRSpatialReference reference_system, double* geotransform)
 {
     this->width = width;
     this->height = height;
     this->cells = cells;
     this->reference_system = reference_system;
-
+    this->geotransform = geotransform;
 }
 int CellMap::get_cell(int x, int y)
 {

src/HeightMap.cpp

@@ -1,6 +1,7 @@
+#include <gdal/cpl_conv.h>
 #include <iostream>
 #include <stdexcept>
-
+#include <omp.h>
 #include <gdal/gdal.h>
 #include "gdal/gdal_priv.h"
 #include <gdal/gdal_frmts.h>
@@ -28,7 +29,11 @@ HeightMap::HeightMap(const char* filepath)
     this->height = band->GetYSize();
     this->min = band->GetMinimum();
     this->max = band-> GetMaximum();
+    //https://gdal.org/api/gdaldataset_cpp.html#_CPPv4N11GDALDataset15GetGeoTransformEPd
+    this->geotransform = (double *) CPLMalloc(sizeof(double)*6);
     this->reference_system = *(file->GetSpatialRef());
+
+    file->GetGeoTransform(this->geotransform);
     
     this->data = (float *) CPLMalloc(sizeof(float)*width*height);
     CPLErr error = band->RasterIO( GF_Read, 0, 0, width, height,
@@ -43,4 +48,46 @@ float HeightMap::get_pixel(int x, int y)
     int offset = ((this->width * y) + x);
     //std::cout << "  offset: " << offset << " " << x << ","<< y;
     return *(this->data + offset);
+}
+
+void HeightMap::blur(float standard_deviation)
+{
+    // standard_deviation does not do anything yet. This is currently a simple box blur
+    int kernel_height = 5;
+    int kernel_width = 5;
+    int kernel_size = kernel_height*kernel_width;
+    float* kernel = (float*) CPLMalloc(sizeof(float)*kernel_size);
+    for (int i=0; i<kernel_size; i++)
+    {
+        *(kernel + i) = 1.0;
+    }
+
+    float* blurred = (float *) CPLMalloc(sizeof(float)*this->width*this->height);
+    #pragma omp parallel
+    {
+    #pragma omp for
+    for (int i = 0; i < this->height * this->width; i++)
+    {
+        float blurred_pixel = 0;
+        for (int j = 0; j < kernel_size; j++)
+        {
+            int x = j%kernel_width - kernel_width/2 + i%this->width;
+            int y = j/kernel_width - kernel_height/2 + i/this->width;
+            if (x<0 || x>=this->width)
+            {
+                x = 0;
+            }
+            
+            if (y<0 || y>=this->height)
+            {
+                y = 0;
+            }
+            blurred_pixel += this->get_pixel(x, y);
+        }
+        *(blurred + i) = blurred_pixel/float(kernel_size);
+    }
+    }
+    free(this->data);
+    this->data = blurred;
+    blurred = nullptr;
 }

src/contour_creator.hh

@@ -9,6 +9,8 @@ class HeightMap
 {
     public:
         float* data;
+        double* geotransform; //!< Six double buffer for storing the affine transformations
+        // https://gdal.org/api/gdaldataset_cpp.html#_CPPv4N11GDALDataset15GetGeoTransformEPd
         int width; //!< width of image in pixels
         int height; //!< height of image in pixels
         float min; //!< Minimum value in image
@@ -17,6 +19,7 @@ class HeightMap
 
         HeightMap(const char* filepath);
         float get_pixel(int x,int y);
+        void blur(float standard_deviation);
 };
 
 /**
@@ -26,10 +29,24 @@ class CellMap
 {
     public:
         uint8_t* cells; //!< pointer to the first cell in the array. uint8_t is a 8 bit unsigned integer 
+        double* geotransform; //!< Six double buffer for storing the affine transformations
         int width; //!< width of image in cells
         int height; //!< height of image in cells
         OGRSpatialReference reference_system;
-
-        CellMap(int width, int height, uint8_t* cells, OGRSpatialReference reference_system);
+        CellMap(int width, int height, uint8_t* cells, OGRSpatialReference reference_system, double* geotransform);
         int get_cell(int x,int y);
-};
+};
+
+class Point
+{
+    public:
+        int x;
+        int y;
+        int mscase;
+        bool allocated = false;
+        Point(int x, int y, int mscase){
+            this -> x = x;
+            this -> y = y;
+            this -> mscase = mscase;
+        };
+};

src/main.cpp

@@ -1,59 +1,191 @@
 #include "contour_creator.hh"
+#include <algorithm>
+#include <array>
 #include <gdal/ogr_api.h>
 #include "ogrsf_frmts.h"
+#include <gdal/ogr_core.h>
+#include <gdal/ogr_feature.h>
+#include <gdal/ogr_geometry.h>
 #include <iostream>
 #include <ostream>
+#include <sys/types.h>
+#include <tuple>
 #include <vector>
 #include <cstdint>
 #include <gdal/gdal.h>
 #include "gdal/gdal_priv.h"
 #include <gdal/gdal_frmts.h>
 #include <omp.h>
+#include "argh.h"
 
-CellMap produce_cellmap(HeightMap* heightmap, float z)
+std::vector<Point> produce_cellmap(HeightMap* heightmap, float z)
 {
-    int length = (heightmap->width-1)*(heightmap->height-1);
+    int length = (heightmap->width-1)*(heightmap->height-1); // Defining length of vector
     uint8_t *cells = (uint8_t *) CPLMalloc(sizeof(uint8_t)*length);
+    std::vector<Point> points; // Initiating a vector of points
     for (int i = 0; i<length; i++) {
         int y = i/(heightmap->width-1);
         int x = i%(heightmap->width-1);
-        uint8_t result = (heightmap->get_pixel(x,y)>z) + 
-        (heightmap->get_pixel(x+1,y)>z)*2 +
-        (heightmap->get_pixel(x+1,y+1)>z)*4 +
-        (heightmap->get_pixel(x,y+1)>z)*8;
-        *(cells + i) = result;
+        uint8_t result = (heightmap->get_pixel(x,y)>z)*8 + 
+        (heightmap->get_pixel(x+1,y)>z)*4 +
+        (heightmap->get_pixel(x+1,y+1)>z)*2 +
+        (heightmap->get_pixel(x,y+1)>z);
+        if (result != 0 and result != 15 ) {
+            points.push_back(Point(x, y, result));
+        };
     }
-    
-    return CellMap(heightmap->width-1, heightmap->height-1, cells, heightmap->reference_system);
-
-
+    return points;
 }
 
-std::vector<CellMap> vector_cellmap(HeightMap* heightmap, int interval)
+bool is_in(int value, std::array<int, 8> array)
+{
+    return std::binary_search(array.begin(), array.end(), value);
+}
+
+std::vector<std::vector<Point>> create_lines(HeightMap* heightmap, int interval)
 {
     int num_contours = (heightmap->max - heightmap->min)/interval;
-    std::vector<CellMap> vector_contours;
-    omp_set_num_threads(12);
+    std::vector<std::vector<Point>> vector_contours;
+
+    std::array<int,8> north{4, 5,6,7,8,9,10,11};
+    std::array<int,8> south{1,2,5,6,9,10,13,14};
+    std::array<int,8> east{2,3,4,5,10,11,12,13};
+    std::array<int,8> west{1,3,5,7,8,10,12,14};
 
     #pragma omp parallel
     {
-        std::vector<CellMap> vec_private;
+        std::vector<std::vector<Point>> vec_private;
         #pragma omp for
         for (int i = 1; i <= num_contours; i++) 
         {
-            vec_private.push_back(produce_cellmap(heightmap, heightmap->min + interval*i));
+            auto points = produce_cellmap(heightmap, heightmap->min + interval*i);
+            std::vector<Point> line;
+            int x;
+            int y;
+            int points_allocated = 0;
+            x = points[0].x;
+            y = points[0].y;
+            int current_case = points[0].mscase;
+            points[0].allocated = true;
+            line.push_back(points[0]);
+            for (int j = 0; j < points.size(); j++){
+                for (int k = 0; k < points.size(); k++){
+                    Point* candidate = &points[k];
+                    if (!candidate->allocated) {
+                        if (candidate->x == x +1 && candidate->y == y /*&& is_in(current_case, east)*/) {
+                            candidate->allocated = true;
+                            x = candidate->x;
+                            y = candidate->y;
+                            current_case = candidate->mscase;
+                            line.push_back(*candidate);
+                            points_allocated++;
+                            break;
+                        }
+                        else if (candidate->x == x -1 && candidate->y == y /*&& is_in(current_case, west)*/) {
+                            x = candidate->x;
+                            y = candidate->y;
+                            current_case = candidate->mscase;
+                            candidate->allocated = true;
+                            line.push_back(*candidate);
+                            points_allocated++;
+                            break;
+                        }
+                        else if (candidate->x == x && candidate->y == y + 1 /*&& is_in(current_case, north)*/) {
+                            x = candidate->x;
+                            y = candidate->y;
+                            current_case = candidate->mscase;
+                            candidate->allocated = true;
+                            line.push_back(*candidate);
+                            points_allocated++;
+                            break;
+                        }
+                        else if (candidate->x == x && candidate->y == y - 1 /*&& is_in(current_case, south)*/) {
+                            x = candidate->x;
+                            y = candidate->y;
+                            current_case = candidate->mscase;
+                            candidate->allocated = true;
+                            line.push_back(*candidate);
+                            points_allocated++;
+                            break;
+                        }
+                    }
+                }
+                if (j > points_allocated)
+                {
+                    vec_private.push_back(line);
+                    line.clear();
+                    //std::cout << points.size() << " ";
+                    for (int k = 0; k < points.size(); k++){
+                        Point* candidate = &points[k];
+                        if (!candidate->allocated)
+                        {
+                            line.push_back(*candidate);
+                            candidate->allocated = true;
+                            x = candidate->x;
+                            y = candidate->y;
+                            current_case = candidate->mscase;
+                            points_allocated++;
+                            break;
+                        }
+                    }
+                }
+            }
         }
         #pragma omp critical
-        vector_contours.insert(vector_contours.end(), vec_private.begin(), vec_private.end());
 
+        vector_contours.insert(vector_contours.end(), vec_private.begin(), vec_private.end());
     }
         return vector_contours;
 }
 
-void write_output_file(std::vector<CellMap> cellmaps, const char *filepath)
+std::tuple<double, double> local_to_projected(double* geotransform, int x, int y)
+{
+    return {
+        geotransform[1] * x + geotransform[2] * y +
+        geotransform[1] * 0.5 + geotransform[2] * 0.5 + geotransform[0],
+        geotransform[4] * x + geotransform[5] * y +
+        geotransform[4] * 0.5 + geotransform[5] * 0.5 + geotransform[3]
+        };
+}
+
+constexpr std::tuple<double, double, double, double> marching_squares_lookup(int mcase)
+{
+    switch (mcase) {
+        case 1:
+            return {0, 0.5, 0.5, 0};
+        case 14:
+            return {0.5, 0, 0, 0.5};
+        case 2: 
+            return {0.5, 0, 1, 0.5};
+        case 13:
+            return {1, 0.5, 0.5, 0};
+        case 3:
+            return {0, 0.5, 1, 0.5};
+        case 12:
+            return {1, 0.5, 0, 0.5};
+        case 4:
+            return {0.5, 1, 1, 0.5};
+        case 11:
+            return {1, 0.5, 0.5, 1};
+        case 5: 
+        case 10:
+            return {0, 0, 0, 0}; //FIXME
+        case 6: 
+            return {0.5, 1, 0.5, 0};
+        case 9:
+            return {0.5, 0, 0.5, 1};
+        case 7: 
+            return {0, 0.5, 0.5, 1};
+        case 8:
+            return {0.5, 0.5, 0, 0.5};
+
+        
+    };
+}
+void write_output_file(std::vector<std::vector<Point>> all_points, const char *filepath, HeightMap* heightmap)
 {
 
-    const char *pszDriverName = "ESRI Shapefile";
+    const char *pszDriverName = "GeoJSON";
     GDALDriver *poDriver;
 
     GDALAllRegister();
@@ -76,7 +208,7 @@ void write_output_file(std::vector<CellMap> cellmaps, const char *filepath)
 
     OGRLayer *poLayer;
 
-    poLayer = poDS->CreateLayer( "contours", &(cellmaps[0]).reference_system, wkbPoint, NULL );
+    poLayer = poDS->CreateLayer( "contours", &heightmap->reference_system, wkbLineString, NULL );
     if( poLayer == NULL )
     {
         printf( "Layer creation failed.\n" );
@@ -92,81 +224,101 @@ void write_output_file(std::vector<CellMap> cellmaps, const char *filepath)
         printf( "Creating Name field failed.\n" );
         exit( 1 );
     }
-    for (int j = 0; j < cellmaps.size(); j++)
+    int width = heightmap->width -1;
+    int height = heightmap->height -1;
+    int size = width * height;
+
+    for (int j = 0; j < all_points.size(); j++)
     {
-        CellMap* cellmap = &cellmaps[j];
-        for (int i = 0; i<cellmap->height*cellmap->width; i++) {
-            if (*(cellmap->cells + i) != 0 && *(cellmap->cells + i) != 15)
+        OGRFeature *feature;
+        OGRLineString *geometry = new OGRLineString();
+        feature = OGRFeature::CreateFeature( poLayer->GetLayerDefn() );
+        feature->SetField( "Name", j );
+
+        std::vector<Point> points = all_points[j];
+        
+        bool left_to_right = true;
+        
+        if ((points[0].y - points[1].y) < 0)
+            left_to_right = true;
+        else
+            left_to_right = false;
+
+        for (int k = 0; k < points.size(); k++)
+        {
+            bool left_to_right = true;
+        
+            if ((points[k].x - points[k-1].x) < 0)
+                left_to_right = false;
+            bool top_to_bottom = true;
+            if ((points[k].y - points[k-1].y) < 0)
+                left_to_right = false;
+
+
+
+            int x_raw = points[k].x;
+            int y_raw = points[k].y;
+            auto [x, y] = local_to_projected(heightmap->geotransform, x_raw, y_raw);
+
+            auto [x1, y1, x2, y2] = marching_squares_lookup(points[k].mscase);
+            
+            if (left_to_right or !top_to_bottom)
             {
-                int x_int = i%cellmap->width;
-                int y_int = cellmap->height*cellmap->width - i/cellmap->width;
-                double x = double(x_int);
-                double y = double(y_int);
-
-                OGRFeature *poFeature;
-
-                poFeature = OGRFeature::CreateFeature( poLayer->GetLayerDefn() );
-                poFeature->SetField( "Name", *(cellmap->cells + i) );
-
-                //OGRSpatialReference local;
-
-                //auto poCT = OGRCreateCoordinateTransformation( &local, &cellmap->reference_system );
-                
-                /*
-                if( poCT == NULL || !poCT->Transform( 1, &x, &y ) )
-                    printf( "Transformation failed.\n" );
-                */
-                OGRPoint pt;
-                pt.setX( x );
-                pt.setY( y );
-
-                poFeature->SetGeometry( &pt );
-
-                if( poLayer->CreateFeature( poFeature ) != OGRERR_NONE )
-                {
-                    printf( "Failed to create feature in shapefile.\n" );
-                    exit( 1 );
-                }
-
-                OGRFeature::DestroyFeature( poFeature );
+                geometry->setPoint(geometry->getNumPoints(),x + (x1/6) ,y + (y1/6));
+                geometry->setPoint(geometry->getNumPoints(),x + (x2/6) ,y + (y2/6));
+            }
+            else {
+                geometry->setPoint(geometry->getNumPoints(),x + (x2/6) ,y + (y2/6));
+                geometry->setPoint(geometry->getNumPoints(),x + (x1/6) ,y + (y1/6));
             }
         }
+
+        if ( feature->SetGeometry(geometry) != OGRERR_NONE)
+        {
+            printf( "Failed to set geometry.\n" );
+            exit( 1 );
+        }
+        OGRGeometryFactory::destroyGeometry(geometry);
+        if( poLayer->CreateFeature( feature ) != OGRERR_NONE )
+        {
+            printf( "Failed to create feature in shapefile.\n" );
+            exit( 1 );
+        }
+        OGRFeature::DestroyFeature( feature );
     }
-
     GDALClose( poDS );
-    /*
-    OGRDataSourceH datasource = OGR_Dr_CreateDataSource(OGRGetDriverByName("GeoJSON"), "contour.geojson", new char*);
-    OGRSpatialReference reference_system = cellmap->reference_system;
-    OGRLayerH layer = OGR_DS_CreateLayer(datasource, "contour", &reference_system, wkbLineString25D, new char*);
-    
-    auto feature = OGR_F_Create(OGR_L_GetLayerDefn(static_cast<OGRLayerH>(layer)));
-
-    OGRGeometryH geometry = OGR_G_CreateGeometry(wkbLineString25D);
-    */
 }
 
 int main(int argc, const char* argv[])
 {
-    const char* filepath = argv[1];
-    HeightMap map(filepath); 
-    
-    std::cout << "x: " << map.width << "    y: " << map.height << "\n";
-    std::cout << "max: " << map.max << "    min: " << map.min << "\n";
-    
-    auto cellmap = produce_cellmap(&map, 40);
-    /*
-    for (int y = 0; y < cellmap.height; y++)
+    argh::parser cmdl(argv);
+
+    if (cmdl[{ "-h", "--help" }])
     {
-        for (int x = 0; x < cellmap.width; x++)
-        {
-            if (cellmap.get_cell(x, y) && cellmap.get_cell(x, y)!=15) {
-                std::cout << x << ","<< y << "=" << cellmap.get_cell(x, y) << " ";
-            }
-        }
-       //std::cout << "\n";
+        std::cout << "Usage:\n"
+            << "contour_creator [OPTIONS] <input_file>\n"
+            << "-o; --output <FILENAME.geojson> - File to write output to (Default: contours.geojson)\n"
+            << "-i; --interval <int> - Set the interval between contours (Default: 5)\n"
+            << "-b; --blur - Blur the image\n"
+            << "--stats - Print statistical information about the heightmap\n";
+            exit(0);
     }
-    */
+    int interval;
+    cmdl({"-i", "--interval"}, 5) >> interval;
+    if (interval <= 0)
+        std::cerr << "Interval must be valid positive integer!" << "\n";
     
-    auto cellmaps = vector_cellmap(&map, 5);
-    write_output_file(cellmaps, "out.shp");
+    std::string output_file;
+    cmdl({"-o", "--output"}, "contours.geojson") >> output_file;
+
+    std::string input_file;
+    cmdl(1) >> input_file;
+    
+
+    HeightMap map(input_file.c_str());
+    if (cmdl[{"-b", "--blur"}])
+        map.blur(0.8);
+    auto lines = create_lines(&map, interval);
+    write_output_file(lines, output_file.c_str(), &map);
+    std::cout << "Contours written to " << output_file << " 🗺️\n";
 }