/// <summary>
/// Adds an inner contour to the present object. The inner contour should contain
/// the points on the inner rim of the region of interest (innermost points that are
/// still foreground).
/// </summary>
/// <param name="inner">The points on the inner rim of the region, surrounding any "holes".</param>
public void AddInnerContour(PolygonPoints inner)
{
Inner.Add(inner ?? throw new ArgumentNullException(nameof(inner)));
TotalPixels -= inner.VoxelCounts.Total;
}
/// <summary>
/// Extracts polygons by walking the edge of the foreground values of the worker volume.
/// This method will return closed polygons. Also, the polygons will be filled (any holes removed).
/// The <paramref name="foundPolygons"/> argument will be updated in place, by marking all voxels
/// that are found to be inside of a polygon with the index of that polygon.
/// The first new polygon that is found will be given the number supplied in <paramref name="firstNewPolygon"/>
/// (must be 1 or higher)
/// </summary>
/// <param name="binaryVolume">The volume we are extracting polygons from. Must only contain values 0 and 1.</param>
/// <param name="foundPolygons">A volume that contains the IDs for all polygons that have been found already. 0 means no polygon found.</param>
/// <param name="searchInsidePolygon">For walking along edges, limit to the voxels that presently are assigned to
/// the polygon given here.</param>
/// <param name="isInnerPolygon">If true, the polygon will walk along boundaries around regions with
/// voxel value 0 (background), but keep the polyon points on voxel values 1, counterclockwises.</param>
/// <param name="firstNewPolygon">The ID for the first polygon that is found.</param>
/// <returns>A collection of polygons and there respective sizes (number of foreground points in each polygon)</returns>
private static Dictionary <ushort, PolygonPoints> ExtractPolygons(
Volume2D <byte> binaryVolume,
ushort[] foundPolygons,
ushort searchInsidePolygon,
bool isInnerPolygon,
ushort firstNewPolygon)
{
if (binaryVolume == null)
{
throw new ArgumentNullException(nameof(binaryVolume));
}
if (foundPolygons == null)
{
throw new ArgumentNullException(nameof(foundPolygons));
}
if (firstNewPolygon < 1)
{
throw new ArgumentOutOfRangeException(nameof(firstNewPolygon), "Polygon index 0 is reserved for 'not assigned'");
}
var foregroundId = isInnerPolygon ? (byte)0 : (byte)1;
var polygons = new Dictionary <ushort, PolygonPoints>();
var dimX = binaryVolume.DimX;
var dimY = binaryVolume.DimY;
var volumeArray = binaryVolume.Array;
for (var y = 0; y < dimY; y++)
{
// Manually computing index, rather than relying on GetIndex, brings substantial speedup.
var offsetY = y * dimX;
for (var x = 0; x < dimX; x++)
{
var pixelIndex = x + offsetY;
// Starting point of a new polygon is where we see the desired foreground in the original
// volume, and have either not found any polygon yet (searchInsidePolygon == 0)
// or have found a polygon already and now search for the holes inside it.
if (volumeArray[pixelIndex] == foregroundId && foundPolygons[pixelIndex] == searchInsidePolygon)
{
PointInt startPoint;
if (isInnerPolygon)
{
Debug.Assert(y >= 1, "When searching for innner polygons (holes), expecting that there is foreground in the row above.");
startPoint = new PointInt(x, y - 1);
}
else
{
startPoint = new PointInt(x, y);
}
VoxelCounts voxelCounts;
PointInt[] contourPoints;
if (isInnerPolygon)
{
var innerPoints = FindPolygon(
binaryVolume,
foundPolygons,
searchInsidePolygon,
new PointInt(x, y),
backgroundId: 1,
searchClockwise: true);
voxelCounts = FillPolygon.FillPolygonAndCount(
innerPoints,
foundPolygons,
firstNewPolygon,
binaryVolume,
foregroundId: 0);
contourPoints = FindPolygon(
binaryVolume,
foundPolygons,
searchInsidePolygon,
startPoint,
backgroundId: 0,
searchClockwise: false);
}
else
{
contourPoints = FindPolygon(
binaryVolume,
foundPolygons,
searchInsidePolygon,
startPoint,
backgroundId: 0,
searchClockwise: true);
voxelCounts = FillPolygon.FillPolygonAndCount(
contourPoints,
foundPolygons,
firstNewPolygon,
binaryVolume,
foregroundId);
}
var polygon = new PolygonPoints(
contourPoints,
voxelCounts,
searchInsidePolygon,
isInside: isInnerPolygon,
startPointMinimumY: startPoint);
polygons.Add(firstNewPolygon, polygon);
firstNewPolygon++;
}
}
}
return(polygons);
}
/// <summary>
/// Creates a new instance of the class.
/// </summary>
/// <param name="outer">The points that make up the outer rim of the region, traversed clockwise.</param>
public InnerOuterPolygon(PolygonPoints outer)
{
Outer = outer ?? throw new ArgumentNullException(nameof(outer));
Inner = new List <PolygonPoints>();
TotalPixels = outer.VoxelCounts.Total;
}
