major update for tin.h
This commit is contained in:
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760db80652
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12
demo.cpp
12
demo.cpp
@ -15,9 +15,19 @@ int main(int argc, char const *argv[])
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}
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infile.close();
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std::vector<double> err_records;
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std::vector<vertex2dc*> tin_vert;
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std::vector<triangle*> tin_ele;
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dem2tin(topo, 0, 1000, 0, 1000, 10, 10, tin_vert, tin_ele, 1.0);
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dem2tin(topo, 0, 1000, 0, 1000, 10, 10, tin_vert, tin_ele, 1.0, &err_records);
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// Write a log file
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std::ofstream logfile("topo_TIN.log");
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logfile << "# Insertion Maxi-Error\n";
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for (int i = 0; i < err_records.size(); ++i)
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{
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logfile << i+1 << " " << err_records[i] << std::endl;
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}
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logfile.close();
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// Write a Gmsh's .msh file
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std::ofstream outfile("topo_TIN.msh");
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180
tin.h
180
tin.h
@ -1,10 +1,10 @@
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/**
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* @defgroup TIN
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*
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* @brief Generation of a Triangular Irregular Network (TIN) from a dense DEM grid
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* @brief Generation of a Triangular Irregular Network (TIN) from a dense DEM grid.
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*
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* @author Yi Zhang
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* @date 2021-09-15
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* @date 2021-09-16
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*/
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#ifndef _TIN_DELAUNAY_H
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@ -108,7 +108,7 @@ struct triangle
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l2x = inx - vert[i]->x;
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l2y = iny - vert[i]->y;
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if ((l1x*l2y - l1y*l2x) < 0)
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if ((l1x*l2y - l1y*l2x) < 0) // This condition includes points on the triangle's edge
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{
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return false;
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}
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@ -126,6 +126,25 @@ struct triangle
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};
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// End triangle definition
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// Start DEM definition
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struct dem_point
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{
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double x, y; // position of the DEM location
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double elev; // elevation at the DEM location
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triangle *host; // host triangle of the DEM location
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std::vector<triangle*> circum_host; // triangles which circumcircles include the location
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dem_point() : x(NAN), y(NAN), elev(NAN), host(nullptr) {}
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dem_point(double inx, double iny, double inelev) {set(inx, iny, inelev);}
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void set(double inx, double iny, double inelev)
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{
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x = inx; y = iny; elev = inelev; host = nullptr;
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circum_host.clear();
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return;
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}
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};
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// End DEM definition
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/**
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* @brief Generate the TIN from the DEM grid
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*
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@ -138,13 +157,16 @@ struct triangle
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* @param[in] dy Data spacing of the DEM grid on the y-axis
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* @param out_verts The output vector of vertex's pointers. The user need to destroy the memories allocated by the function before destroy the vector
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* @param out_tris The output vector of triangle's pointers. The user need to destroy the memories allocated by the function before destroy the vector
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* @param[in] maxi_err Threshold to quit the algorithm. The default is 1e-2
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* @param[in] maxi_err Threshold to quit the algorithm. The default is 1e-0
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* @param[in] err_records If this pointer is not NULL, record maximal error values after each insertion of vertex.
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*/
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void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ymin, double ymax,
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double dx, double dy, std::vector<vertex2dc*> &out_verts, std::vector<triangle*> &out_tris, double maxi_err = 1e-2)
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double dx, double dy, std::vector<vertex2dc*> &out_verts, std::vector<triangle*> &out_tris,
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double maxi_err = 1e-0, std::vector<double> *err_records = nullptr)
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{
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if (!out_verts.empty()) out_verts.clear();
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if (!out_tris.empty()) out_tris.clear();
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if (err_records != nullptr && !err_records->empty()) err_records->clear();
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if (dx <= 0.0 || dy <= 0.0 || maxi_err <= 0.0) return;
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if (xmin >= xmax || ymin >= ymax || (xmin + dx) > xmax || (ymin + dy) > ymax) return;
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@ -154,22 +176,37 @@ void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ym
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if (dem.size() != xnum*ynum) return;
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// Prepare the DEM points
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std::vector<dem_point> dem_grid(xnum*ynum);
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std::vector<dem_point>::iterator d_iter;
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for (int i = 0; i < ynum; ++i)
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{
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for (int j = 0; j < xnum; ++j)
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{
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dem_grid[j + i*xnum].set(xmin + dx*j, ymin + dy*i, dem[j + i*xnum]);
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}
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}
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vertex2dc *tmp_vert = nullptr;
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tmp_vert = new vertex2dc(xmin, ymin, dem[0], out_verts.size()); // lower left corner
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tmp_vert = new vertex2dc(xmin, ymin, dem_grid[0].elev, out_verts.size()); // lower left corner
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out_verts.push_back(tmp_vert);
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d_iter = dem_grid.begin(); dem_grid.erase(d_iter);
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tmp_vert = new vertex2dc(xmax, ymin, dem[xnum-1], out_verts.size()); // lower right corner
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tmp_vert = new vertex2dc(xmax, ymin, dem_grid[xnum-2].elev, out_verts.size()); // lower right corner. Note the first location is already erased
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out_verts.push_back(tmp_vert);
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d_iter = dem_grid.begin() + (xnum - 2); dem_grid.erase(d_iter);
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tmp_vert = new vertex2dc(xmax, ymax, dem[xnum*ynum-1], out_verts.size()); // upper right corner
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tmp_vert = new vertex2dc(xmax, ymax, dem_grid[xnum*ynum-3].elev, out_verts.size()); // upper right corner. Note the first two locations are already erased
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out_verts.push_back(tmp_vert);
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d_iter = dem_grid.begin() + (xnum*ynum - 3); dem_grid.erase(d_iter);
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tmp_vert = new vertex2dc(xmin, ymax, dem[xnum*(ynum-1)], out_verts.size()); // upper left corner
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tmp_vert = new vertex2dc(xmin, ymax, dem_grid[xnum*(ynum-1) - 2].elev, out_verts.size()); // upper left corner. Note the first two locations are already erased
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out_verts.push_back(tmp_vert);
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d_iter = dem_grid.begin() + (xnum*(ynum-1) - 2); dem_grid.erase(d_iter);
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triangle *tmp_tri = nullptr;
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std::vector<triangle*> cnst_tri;
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std::vector<triangle*> cnst_tri, new_tri;
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std::vector<triangle*>::iterator t_iter;
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if (!is_collinear(out_verts[0], out_verts[1], out_verts[2])) // Do not create triangle if the vertexes are collinear
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@ -184,12 +221,39 @@ void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ym
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out_tris.push_back(tmp_tri);
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}
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// Find host triangle for all DEM locations
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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for (int t = 0; t < out_tris.size(); ++t)
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{
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if (out_tris[t]->bound_location(dem_grid[i].x, dem_grid[i].y))
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{
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dem_grid[i].host = out_tris[t];
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break; // already found, no need to search more
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}
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}
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}
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// Find circum_host triangles for all DEM locations
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double dist;
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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for (int t = 0; t < out_tris.size(); ++t)
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{
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dist = (out_tris[t]->cx - dem_grid[i].x) * (out_tris[t]->cx - dem_grid[i].x)
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+ (out_tris[t]->cy - dem_grid[i].y) * (out_tris[t]->cy - dem_grid[i].y);
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if ((dist - out_tris[t]->cr) <= ZERO) // Points on the circumcircle are also included
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{
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dem_grid[i].circum_host.push_back(out_tris[t]);
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// no beak here. There might be more than one triangle's circumcircle includes the DEM location
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}
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}
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}
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int now_maxi_id;
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double now_x, now_y, now_err;
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double now_maxi_err;
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double now_err, now_maxi_err;
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bool removed;
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double dist;
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edge tmp_edge;
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std::vector<edge> cnst_edge;
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std::vector<edge>::iterator e_iter;
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@ -197,47 +261,51 @@ void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ym
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do // quit til the threshold is meet
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{
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// loop all DEM data to find the location with maximal error
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// this part is very time consuming. We will fix it later
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now_maxi_err = -1.0;
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for (int i = 0; i < xnum*ynum; ++i)
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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now_x = (i%xnum)*dx + xmin;
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now_y = (i/xnum)*dy + ymin;
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for (int e = 0; e < out_tris.size(); ++e)
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{
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if (out_tris[e]->bound_location(now_x, now_y))
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{
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now_err = fabs(out_tris[e]->interpolate(now_x, now_y) - dem[i]);
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now_err = fabs(dem_grid[i].host->interpolate(dem_grid[i].x, dem_grid[i].y) - dem_grid[i].elev);
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if (now_err > now_maxi_err)
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{
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now_maxi_err = now_err;
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now_maxi_id = i;
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}
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break;
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}
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}
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if (err_records != nullptr)
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{
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err_records->push_back(now_maxi_err);
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}
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// create a new vertex
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now_x = (now_maxi_id%xnum)*dx + xmin;
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now_y = (now_maxi_id/xnum)*dy + ymin;
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tmp_vert = new vertex2dc(now_x, now_y, dem[now_maxi_id], out_verts.size());
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tmp_vert = new vertex2dc(dem_grid[now_maxi_id].x, dem_grid[now_maxi_id].y, dem_grid[now_maxi_id].elev, out_verts.size());
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out_verts.push_back(tmp_vert);
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// determine triangles that include the point and add the triangle to the cnst_tri and remove it from out_tris
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// this is also a part that could take a lot of time if we are working with a large amount of points. We will fix it later
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// Move triangles which circumcircles include the new vertex to the cnst_tri and remove it from out_tris
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cnst_tri.clear();
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for (int i = 0; i < dem_grid[now_maxi_id].circum_host.size(); ++i)
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{
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cnst_tri.push_back(dem_grid[now_maxi_id].circum_host[i]);
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}
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for (int i = 0; i < cnst_tri.size(); ++i)
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{
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for (t_iter = out_tris.begin(); t_iter != out_tris.end(); )
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{
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tmp_tri = *t_iter;
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dist = (tmp_tri->cx - now_x) * (tmp_tri->cx - now_x) + (tmp_tri->cy - now_y) * (tmp_tri->cy - now_y);
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if ((dist - tmp_tri->cr) <= ZERO) // Points on the circumcircle are also included
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if (cnst_tri[i] == tmp_tri)
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{
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t_iter = out_tris.erase(t_iter);
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cnst_tri.push_back(tmp_tri);
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break; // no need to search more
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}
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else t_iter++;
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}
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}
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// clear host and circumcircle triangles for the used DEM location
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dem_grid[now_maxi_id].host = nullptr;
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dem_grid[now_maxi_id].circum_host.clear();
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d_iter = dem_grid.begin() + now_maxi_id; dem_grid.erase(d_iter);
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// loop to remove duplicate edges
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cnst_edge.clear();
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@ -267,12 +335,59 @@ void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ym
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}
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// construct new triangles and add to out_tris
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new_tri.clear();
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for (int c = 0; c < cnst_edge.size(); ++c)
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{
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if (!is_collinear(cnst_edge[c].vert[0], cnst_edge[c].vert[1], tmp_vert)) // Do not create triangle if the vertexes are collinear
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{
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tmp_tri = new triangle(cnst_edge[c].vert[0], cnst_edge[c].vert[1], tmp_vert); // order the vertex anti-clock wise
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out_tris.push_back(tmp_tri);
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new_tri.push_back(tmp_tri);
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}
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}
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// purge circumcircle triangles for all DEM data
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for (int c = 0; c < cnst_tri.size(); ++c)
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{
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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for (t_iter = dem_grid[i].circum_host.begin(); t_iter != dem_grid[i].circum_host.end(); )
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{
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if (cnst_tri[c] == *t_iter)
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{
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t_iter = dem_grid[i].circum_host.erase(t_iter);
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break; // no need to search more
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}
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else t_iter++;
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}
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}
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}
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// loop all DEM data to update host and circumcircle triangles
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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for (int n = 0; n < new_tri.size(); ++n) // search in newly created triangles to find new host
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{
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if (new_tri[n]->bound_location(dem_grid[i].x, dem_grid[i].y))
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{
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dem_grid[i].host = new_tri[n];
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break; // already found, no need to search more
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}
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}
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}
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// Find circum_host triangles for all DEM locations
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for (int i = 0; i < dem_grid.size(); ++i)
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{
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for (int n = 0; n < new_tri.size(); ++n) // search in newly created triangles to find new circumcircle triangles
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{
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dist = (new_tri[n]->cx - dem_grid[i].x) * (new_tri[n]->cx - dem_grid[i].x)
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+ (new_tri[n]->cy - dem_grid[i].y) * (new_tri[n]->cy - dem_grid[i].y);
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if ((dist - new_tri[n]->cr) <= ZERO) // Points on the circumcircle are also included
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{
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dem_grid[i].circum_host.push_back(new_tri[n]);
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// no beak here. There might be more than one triangle's circumcircle includes the DEM location
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}
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}
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}
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@ -282,6 +397,7 @@ void dem2tin(const std::vector<double> &dem, double xmin, double xmax, double ym
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tmp_tri = cnst_tri[c];
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delete tmp_tri; tmp_tri = nullptr;
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}
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} while (now_maxi_err >= maxi_err);
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return;
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2343
topo_TIN.log
Normal file
2343
topo_TIN.log
Normal file
File diff suppressed because it is too large
Load Diff
40
topo_TIN.msh
40
topo_TIN.msh
@ -2339,9 +2339,9 @@ $Nodes
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2334 850 360 40.4211
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2335 830 360 45.5722
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2336 340 630 112.757
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2337 300 190 15.6154
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2338 350 260 26.3352
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2339 340 260 24.4764
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2337 350 260 26.3352
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2338 340 260 24.4764
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2339 300 190 15.6154
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2340 540 1000 1.93313
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2341 480 1000 2.29036
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2342 440 920 15.8236
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@ -6944,20 +6944,20 @@ $Elements
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4590 2 0 2253 342 2336
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4591 2 0 336 2011 2336
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4592 2 0 2011 2253 2336
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4593 2 0 1175 61 2337
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4594 2 0 1575 1175 2337
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4595 2 0 2251 1575 2337
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4596 2 0 61 1930 2337
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4597 2 0 1930 1749 2337
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4598 2 0 1749 2251 2337
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4599 2 0 441 1735 2338
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4600 2 0 2103 441 2338
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4601 2 0 1735 1641 2338
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4602 2 0 1641 2266 2339
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4603 2 0 2338 1641 2339
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4604 2 0 2101 2103 2339
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4605 2 0 2103 2338 2339
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4606 2 0 2266 2101 2339
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4593 2 0 441 1735 2337
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4594 2 0 2103 441 2337
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4595 2 0 1735 1641 2337
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4596 2 0 1641 2266 2338
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4597 2 0 2337 1641 2338
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4598 2 0 2101 2103 2338
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4599 2 0 2103 2337 2338
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4600 2 0 2266 2101 2338
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4601 2 0 1175 61 2339
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4602 2 0 1575 1175 2339
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4603 2 0 2251 1575 2339
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4604 2 0 61 1930 2339
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4605 2 0 1930 1749 2339
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4606 2 0 1749 2251 2339
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4607 2 0 1728 100 2340
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4608 2 0 1866 1728 2340
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4609 2 0 1986 2030 2341
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@ -9335,9 +9335,9 @@ $NodeData
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2334 40.4211
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2335 45.5722
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2336 112.757
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2337 15.6154
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2338 26.3352
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2339 24.4764
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2337 26.3352
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2338 24.4764
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2339 15.6154
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2340 1.93313
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2341 2.29036
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2342 15.8236
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