void HexBin::done(PointTableRef table)
{
m_grid->processSample();
try
{
m_grid->findShapes();
m_grid->findParentPaths();
}
catch (hexer::hexer_error& e)
{
m_metadata.add("error", e.what(),
"Hexer threw an error and was unable to compute a boundary");
m_metadata.add("boundary", "MULTIPOLYGON EMPTY",
"Empty polygon -- unable to compute boundary");
return;
}
std::ostringstream offsets;
offsets << "MULTIPOINT (";
for (int i = 0; i < 6; ++i)
{
hexer::Point p = m_grid->offset(i);
offsets << p.m_x << " " << p.m_y;
if (i != 5)
offsets << ", ";
}
offsets << ")";
m_metadata.add("edge_length", m_edgeLength, "The edge length of the "
"hexagon to use in situations where you do not want to estimate "
"based on a sample");
m_metadata.add("estimated_edge", m_grid->height(),
"Estimated computed edge distance");
m_metadata.add("threshold", m_grid->denseLimit(),
"Minimum number of points inside a hexagon to be considered full");
m_metadata.add("sample_size", m_sampleSize, "Number of samples to use "
"when estimating hexagon edge size. Specify 0.0 or omit options "
"for edge_size if you want to compute one.");
m_metadata.add("hex_offsets", offsets.str(), "Offset of hex corners from "
"hex centers.");
std::ostringstream polygon;
polygon.setf(std::ios_base::fixed, std::ios_base::floatfield);
polygon.precision(m_precision);
m_grid->toWKT(polygon);
if (m_outputTesselation)
{
MetadataNode hexes = m_metadata.add("hexagons");
for (HexIter hi = m_grid->hexBegin(); hi != m_grid->hexEnd(); ++hi)
{
HexInfo h = *hi;
MetadataNode hex = hexes.addList("hexagon");
hex.add("density", h.density());
hex.add("gridpos", Utils::toString(h.xgrid()) + " " +
Utils::toString((h.ygrid())));
std::ostringstream oss;
// Using stream limits precision (default 6)
oss << "POINT (" << h.x() << " " << h.y() << ")";
hex.add("center", oss.str());
}
m_metadata.add("hex_boundary", polygon.str(),
"Boundary MULTIPOLYGON of domain");
}
/***
We want to make these bumps on edges go away, which means that
we want to elimnate both B and C. If we take a line from A -> C,
we need the tolerance to eliminate B. After that we're left with
the triangle ACD and we want to eliminate C. The perpendicular
distance from AD to C is the hexagon height / 2, so we set the
tolerance a little larger than that. This is larger than the
perpendicular distance needed to eliminate B in ABC, so should
serve for both cases.
B ______ C
/ \
A / \ D
***/
double tolerance = 1.1 * m_grid->height() / 2;
double cull = m_cullArg->set() ? m_cullArea : (6 * tolerance * tolerance);
SpatialReference srs(table.anySpatialReference());
pdal::Polygon p(polygon.str(), srs);
pdal::Polygon density_p(polygon.str(), srs);
// If the SRS was geographic, use relevant
// UTM for area and density computation
if (srs.isGeographic())
{
// Compute a UTM polygon
BOX3D box = p.bounds();
int zone = SpatialReference::calculateZone(box.minx, box.miny);
auto makezone = [] (int zone) -> std::string
{
std::ostringstream z;
// Use WGS84 UTM zones
z << "EPSG:327" << abs(zone);
return z.str();
};
SpatialReference utm(makezone(zone));
density_p = p.transform(utm);
}
if (m_doSmooth)
p = p.simplify(tolerance, cull);
std::string boundary_text = p.wkt(m_precision);
m_metadata.add("boundary", boundary_text,
"Approximated MULTIPOLYGON of domain");
m_metadata.addWithType("boundary_json", p.json(), "json",
"Approximated MULTIPOLYGON of domain");
double area = density_p.area();
double density = (double) m_count/ area ;
if (std::isinf(density))
{
density = -1.0;
area = -1.0;
}
m_metadata.add("density", density,
"Number of points per square unit (total area)");
m_metadata.add("area", area, "Area in square units of tessellated polygon");
double moving_avg(0.0);
double avg_count(0.0);
double hex_area(((3 * SQRT_3)/2.0) * (m_grid->height() * m_grid->height()));
int n(0);
point_count_t totalCount(0);
double totalArea(0.0);
for (HexIter hi = m_grid->hexBegin(); hi != m_grid->hexEnd(); ++hi)
{
HexInfo h = *hi;
totalCount += h.density();
totalArea += hex_area;
++n;
}
double avg_density = totalArea /(double) totalCount;
m_metadata.add("avg_pt_per_sq_unit", avg_density, "Number of points "
"per square unit (tessellated area within inclusions)");
double avg_spacing = std::sqrt(1/density);
m_metadata.add("avg_pt_spacing", avg_spacing,
"Avg point spacing (x/y units)");
}
void HexBin::done(PointTableRef table)
{
m_grid->processSample();
m_grid->findShapes();
m_grid->findParentPaths();
std::ostringstream offsets;
offsets << "MULTIPOINT (";
for (int i = 0; i < 6; ++i)
{
hexer::Point p = m_grid->offset(i);
offsets << p.m_x << " " << p.m_y;
if (i != 5)
offsets << ", ";
}
offsets << ")";
m_metadata.add("edge_length", m_edgeLength, "The edge length of the "
"hexagon to use in situations where you do not want to estimate "
"based on a sample");
m_metadata.add("threshold", m_density, "Minimum number of points inside "
"a hexagon to be considered full");
m_metadata.add("sample_size", m_sampleSize, "Number of samples to use "
"when estimating hexagon edge size. Specify 0.0 or omit options "
"for edge_size if you want to compute one.");
m_metadata.add("hex_offsets", offsets.str(), "Offset of hex corners from "
"hex centers.");
if (m_outputTesselation)
{
MetadataNode hexes = m_metadata.add("hexagons");
for (HexIter hi = m_grid->hexBegin(); hi != m_grid->hexEnd(); ++hi)
{
using namespace boost;
HexInfo h = *hi;
MetadataNode hex = hexes.addList("hexagon");
hex.add("density", h.density());
hex.add("gridpos", lexical_cast<std::string>(h.xgrid()) + " " +
lexical_cast<std::string>(h.ygrid()));
std::ostringstream oss;
// Using stream limits precision (default 6)
oss << "POINT (" << h.x() << " " << h.y() << ")";
hex.add("center", oss.str());
}
}
std::ostringstream polygon;
polygon.setf(std::ios_base::fixed, std::ios_base::floatfield);
polygon.precision(m_options.getValueOrDefault<uint32_t>("precision", 8));
m_grid->toWKT(polygon);
m_metadata.add("boundary", polygon.str(),
"Boundary MULTIPOLYGON of domain");
/***
We want to make these bumps on edges go away, which means that
we want to elimnate both B and C. If we take a line from A -> C,
we need the tolerance to eliminate B. After that we're left with
the triangle ACD and we want to eliminate C. The perpendicular
distance from AD to C is the hexagon height / 2, so we set the
tolerance a little larger than that. This is larger than the
perpendicular distance needed to eliminate B in ABC, so should
serve for both cases.
B ______ C
/ \
A / \ D
***/
double tolerance = 1.1 * m_grid->height() / 2;
m_metadata.add("smoothed_boundary",
Geometry::smoothPolygon(polygon.str(), tolerance),
"Smoothed boundary MULTIPOLYGON of domain");
double area = Geometry::computeArea(polygon.str());
double density = (double) m_count / area ;
m_metadata.add("density",
density,
"Number of points per square unit");
m_metadata.add("area",
area,
"Area in square units of tessellated polygon");
}
