Faking thermal image camera with aforge or any other .net solution , emgucv, tbeta

Question

I am simulating a thermal camera effect. I have a webcam at a party pointed at people in front of a wall. I went with background subtraction technique and using Aforge blobcounter I get blobs that I want to fill with gradient coloring. My problem = GetBlobsEdgePoints doesn't return sorted point cloud so I can't use it with, for example, PathGradientBrush from GDI+ to simply draw gradients.

1. I'm looking for simple,fast, algorithm to trace blobs into path (can make mistakes).
2. A way to track blobs received by blobcounter.
3. A suggestion for some other way to simulate the effect.

I took a quick look at Emgu.CV.VideoSurveillance but didn't get it to work (examples are for v1.5 and I went with v2+) but I gave up because people say it's slow on forums.

thanks for reading.

sample code of aforge background removal

            Bitmap bmp =(Bitmap)e.VideoFrame.Clone();
        if (backGroundFrame == null)
        {
            backGroundFrame = (Bitmap)e.VideoFrame.Clone();
            difference.OverlayImage = backGroundFrame;
        }

        difference.ApplyInPlace(bmp);
        bmp = grayscale.Apply(bmp);
        threshold.ApplyInPlace(bmp);

Answer 1

This is the direction i'm going to take (looks best for now):

1. Define a set of points on the blob by my own logic (color of skin blobs should be warmer etc..)

2. draw gradients around those points

               GraphicsPath gp=new GraphicsPath();
               var rect = new Rectangle(CircumferencePoint.X - radius, CircumferencePoint.Y - radius, radius*2, radius*2);
               gp.AddEllipse(rect);
               GradientShaper = new PathGradientBrush(gp);
               GradientShaper.CenterColor = Color.White;
               GradientShaper.SurroundColors = surroundingColors;
               drawBmp.FillPath(GradientShaper,gp);
   

3. mask those gradients with blob shape

               blobCounter.ExtractBlobsImage(bmp,blob,true);
               mask.OverlayImage = blob.Image;
               mask.ApplyInPlace(rslt);
   

4. colorize with color remapping

tnx for the help @Albin

Answer 2

Well, could you post some sample image of the result of GetBlobsEdgePoints, then it might be easier to understand what types if image processing algorithms are needed.

1) You may try a greedy algorithm, first pick a point at random, mark that point as "taken", pick the closest point not marked as "taken" and so on.
You need to find suitable termination conditions. If there can be several disjunct paths you need to find out a definition of how far away points need to be to be part of disjunct paths.

3) If you have a static background you can try to create a difference between two time shifted images, like 200ms apart. Just do a pixel by pixel difference and use abs(diff) as index in your heat color map. That will give more like an edge glow effect of moving objects.