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Added SrtmTileManager::GetBilinearHeight.

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Signed-off-by: Viktor Govako <viktor.govako@gmail.com>
This commit is contained in:
Viktor Govako
2023-02-23 18:55:07 -03:00
committed by Konstantin Pastbin
parent ac50520ca8
commit 767f27e00a
7 changed files with 59 additions and 29 deletions
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31
generator/srtm_parser.cpp
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@@ -135,7 +135,7 @@ geometry::Altitude SrtmTile::GetHeightRC(size_t row, size_t col) const
return ReverseByteOrder(Data()[ix]);
}
geometry::Altitude SrtmTile::GetTriangleHeight(ms::LatLon const & coord) const
double SrtmTile::GetTriangleHeight(ms::LatLon const & coord) const
{
if (!IsValid())
return geometry::kInvalidAltitude;
@@ -179,9 +179,32 @@ geometry::Altitude SrtmTile::GetTriangleHeight(ms::LatLon const & coord) const
double const a2 = ((p3.y - p1.y) * (ll.m_lon - p3.x) + (p1.x - p3.x) * (ll.m_lat - p3.y)) / det;
double const a3 = 1 - a1 - a2;
return static_cast<geometry::Altitude>(std::round(a1 * GetHeightRC(p1.y, p1.x) +
a2 * GetHeightRC(p2.y, p2.x) +
a3 * GetHeightRC(p3.y, p3.x)));
return a1 * GetHeightRC(p1.y, p1.x) + a2 * GetHeightRC(p2.y, p2.x) + a3 * GetHeightRC(p3.y, p3.x);
}
double SrtmTile::GetBilinearHeight(ms::LatLon const & coord) const
{
if (!IsValid())
return geometry::kInvalidAltitude;
auto const ll = GetCoordInSeconds(coord);
m2::Point<int> const p1(static_cast<int>(ll.m_lon), static_cast<int>(ll.m_lat));
auto p2 = p1;
if (p2.x < kArcSecondsInDegree)
++p2.x;
if (p2.y < kArcSecondsInDegree)
++p2.y;
// https://en.wikipedia.org/wiki/Bilinear_interpolation
double const denom = (p2.x - p1.x) * (p2.y - p1.y);
if (denom == 0)
return GetHeightRC(p1.y, p1.x);
return (GetHeightRC(p1.y, p1.x) * (p2.x - ll.m_lon) * (p2.y - ll.m_lat) +
GetHeightRC(p1.y, p2.x) * (ll.m_lon - p1.x) * (p2.y - ll.m_lat) +
GetHeightRC(p2.y, p1.x) * (p2.x - ll.m_lon) * (ll.m_lat - p1.y) +
GetHeightRC(p2.y, p2.x) * (ll.m_lon - p1.x) * (ll.m_lat - p1.y)) / denom;
}
// static