Incorrect X, Y, Width and Height on Subject Rectangle

[weiloonhow]

Hi Guys,

I have build an application using C# WPF and SentiVeillence SDK using the sdk sample as a guide.
I have manage to get the camera image and subject detection (rectangle) to display.

However, I noticed that the rectangle for the subject is not in the correct position.
The X and Y are not really in the correct position. The width and height are slightly smaller.

Does anyone know what could be the issue here?

Thank you guys.

Best Regards,
Lucas

[MartynasV]

Hello Lucas,

Please provide SDK revision number(can be found in SDK root directory, in Revision.txt file).

However, I noticed that the rectangle for the subject is not in the correct position.
The X and Y are not really in the correct position. The width and height are slightly smaller.

With what do you compare?
Can you send example image which shows that rectangle in not correct position?

[weiloonhow]

Hi MartynasV,

Thank you for the reply.
I have managed to find out the root cause after spending half a day.
The position of the subject rectangle was not correct is due to the TranslateTransform and ScaleTransform.
As I am using WPF instead of Winforms, I need to perform a TranslateTransform and ScaleTransform after the NImage was drawn. Follow by a TranslateTransform and ScaleTransform again after the Subject Rectangle was drawn.
I am not too sure if this is really the correct approach.
Would appreciate if any WPF expert could advise me if I am wrong in this.
Below is my code, Thank you so much.

private void PaintScenes(DrawingContext dc)
{
for (int i = 0; i < _sceneData.Count; i++)
{
SceneData data = _sceneData[i];
Rect rect = GetQuadrant(i, _sceneData.Count);

double scalex = 1, scaley = 1;
if (data.Width != 0 && data.Height != 0 && ActualWidth != 0 && ActualHeight != 0)
{
scalex = (double)ActualWidth / data.Width / (ActualWidth / rect.Width);
scaley = (double)ActualHeight / data.Height / (ActualHeight / rect.Height);
}

double scale = Math.Min(scalex, scaley);
double dx = Math.Round((rect.Width - data.Width * scale) / 2.0);
double dy = Math.Round((rect.Height - data.Height * scale) / 2.0);

TranslateTransform translateTransform = new TranslateTransform((float)(rect.X + dx), (float)(rect.Y + dy));
ScaleTransform scaleTransform = new ScaleTransform((float)scale, (float)scale);

if (data.Image != null)
{
if (data.Bmp == null)
data.Bmp = data.Image.ToBitmap();

var imageRect = new Rect
{
X = 0,
Y = 0,
Width = data.Width,
Height = data.Height
};

using (var bitmap = new System.Drawing.Bitmap(data.Bmp))
{
IntPtr hBitmap = bitmap.GetHbitmap();

try
{
var bitmapSource = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
bitmap.Dispose();
dc.DrawImage(bitmapSource, rect);

}
finally
{
DeleteObject(hBitmap);
}
}

dc.PushTransform(scaleTransform);
dc.PushTransform(translateTransform);

}
PaintScene(dc, data);
data.Scene.CleanSceneInfo();

dc.PushTransform(scaleTransform);
dc.PushTransform(translateTransform);
}
}