/// <summary>
/// Removes overlaped duplicates (nms).
/// </summary>
private List <YoloPrediction> Supress(List <YoloPrediction> items)
{
var result = new List <YoloPrediction>(items);
foreach (var item in items) // iterate every prediction
{
foreach (var current in result.ToList()) // make a copy for each iteration
{
if (current == item)
{
continue;
}
var(rect1, rect2) = (item.Rectangle, current.Rectangle);
RectangleF intersection = RectangleF.Intersect(rect1, rect2);
float intArea = intersection.Area(); // intersection area
float unionArea = rect1.Area() + rect2.Area() - intArea; // union area
float overlap = intArea / unionArea; // overlap ratio
if (overlap >= _model.Overlap)
{
if (item.Score >= current.Score)
{
result.Remove(current);
}
}
}
}
return(result);
}
/// <summary>
/// Changes rectangle scale by a minimum amount in term of area change to match the scale of the user-specified size scale.
/// </summary>
/// <param name="rect">Rectangle.</param>
/// <param name="widthHeightRatio">Width / height ratio that must be satisfied.</param>
/// <param name="correctLocation">Moves rectangle to minimize the impact of scaling regarding original location.</param>
/// <returns>Rectangle that has the same scale as </returns>
public static RectangleF ScaleTo(this RectangleF rect, float widthHeightRatio, bool correctLocation = true)
{
var sizeScale = widthHeightRatio;
var newWidthCandidate = rect.Height * sizeScale;
var newHeightCandidate = rect.Width * (1 / sizeScale);
//if we choose newWidth...
var newWidthAreaChangeFactor = rect.Area() / (newWidthCandidate * rect.Height);
newWidthAreaChangeFactor = newWidthAreaChangeFactor - 1; //for how much the area will change (+/- X percent)
//if we choose newHeight...
var newHeightAreaChangeFactor = rect.Area() / (newHeightCandidate * rect.Width);
newHeightAreaChangeFactor = newHeightAreaChangeFactor - 1; //for how much the area will change (+/- X percent)
if (System.Math.Abs(newWidthAreaChangeFactor) < System.Math.Abs(newHeightAreaChangeFactor))
{
var xOffset = 0f;
if (correctLocation)
{
xOffset = -(newWidthCandidate - rect.Width) / 2;
}
return(new RectangleF(rect.X + xOffset, rect.Y, newWidthCandidate, rect.Height));
}
else
{
var yOffset = 0f;
if (correctLocation)
{
yOffset = -(newHeightCandidate - rect.Height) / 2;
}
return(new RectangleF(rect.X, rect.Y + yOffset, rect.Width, newHeightCandidate));
}
}
