How to rotate a stack of images in 3D space?

Question

I have a stack of 2D images. lets say below are the dimensions of this volume.

Depth(Number of images) - 100
Width(Pixels in X axis) - 200
Height(Pixels in Y-axis) - 200

I want to rotate this volume and create Bitmaps out of this. I am using C# to implement this.

Here is what i did:

List<short[]> volumebuffer = new List<short[]>(noImages);
for (int img = 0; imge<noImages; img++)
{

    short[] tmpArray = new short[ImgTotalHeight * ImgTotalWidth];
    int index = 0;
    for (int aHeight = 0; aHeight<ImgTotalHeight; aHeight++)
    {
       for (int aWidth = 0; aWidth<ImgTotalWidth; aWidth++)
       {
           tmpArray[index++] = image[aWidth + aHeight * ImgTotalWidth];

       }
    }
    #append this tmpArray to a List<>
    vomumebuffer.Add(tmpArray);

}

In the above code the volumebuffer will contain all the pixel values of all the images. I am converting each short array of each image to byte array and creating the bitmaps out of it.

Now i want to rotate this volume and create bitmaps out of it. I want create only 90 degree orientations.

I tried to read the pixel values in different axis. Like for reading pixel values in Width-> Depth -> Height order etc..

But this will need many for loops for each orientation.

Is there any better way to achieve orientation of the volume?

Please help me on how i can rotate this volume at 90 degrees in different orientations.

Thanks in advance.

Answer 1

you should add methods to index the volume by x,y,z coordinates. Rotation in 90-degrees steps would then simply be switching places of the indices, keeping one dimension fixed. For example

bitmap[u, v] = volume[0, v, u]

or

bitmap[u, v] = volume[v, 0, u]

or

bitmap[u, v] = volume[xSize - v, u, 0]

there should be 24 valid combinations in total

you can replace 0 with whatever valid value you want, and you need to ensure the u/y coordinates are limited to corresponding volume-dimension.

Edit:

Example using multidimensional arrays in order to make indexing clearer. You would need to exchange this with corresponding code, and convert the result to a bitmap.

        var volume = new ushort[1, 2, 3];
        var bitmap = new ushort[volume.GetLength(2), volume.GetLength(1)];
        for (int v = 0; v < bitmap.GetLength(1); v++)
        {
            for (int u = 0; u < bitmap.GetLength(0); u++)
            {
                bitmap[u, v] = volume[0, v, u];
            }
        }