[vtkusers] 2D view with color overlays over grayscale volumes

[John Drescher]

> I am using the code from vtkINRIA3D to do this however it has several problems.
>
> http://www-sop.inria.fr/asclepios/software/vtkINRIA3D/dashboard/Doxygen/html/vtkImageBlendWithMask_8cxx-source.html
>
> The main problem is that it blends my grayscale image with another LUT
> based image to form a 3D color volume. At the resolution I am using
> this volume is over 700MB. At first the program was using 3 of these
> one for each of the Coronal, Axial and Sagittal views but I patched my
> code to use only 1 buffer.
>
> Anyways I am thinking that this blending operation does not need to be
> done this way. Can I have multiple image actors with different LUTs
> and place the overlay in a layer above the image I want to view?
>

Yesterday I have solved this issue. I added a the following members to
the vtkViewImage2D class:

/// Overlay image				
	vtkImageData*				FGImage;
	vtkImageActor*				FGImageActor;
	vtkImageMapToColors*		FGWindowLevel;
	vtkImageReslice*                       FGImageReslice;


The solution was to handle the FGImage the same as the image.
Performance is good, actually better than with the 3D color volume and
memory usage is less than 1/2 of what it was for my 0.625 CT cases.

void vtkViewImage2D::SetFGImage( vtkImageData* image, vtkLookupTable* lut )
{

	vtkImageActor*			actor = vtkImageActor::New();
	vtkImageMapToColors*	windowLevel = vtkImageMapToColors::New();
	vtkImageReslice*		relsice = vtkImageReslice::New();

	// set up the vtk pipeline
	relsice->SetOutputDimensionality(2);
	relsice->InterpolateOff();
	
	double* spacing = this->GetImage()->GetSpacing();
	image->SetSpacing(spacing);

	double* origin = this->GetImage()->GetOrigin();
	image->SetOrigin(origin);

	image->Update();

	windowLevel->SetLookupTable(lut);
	windowLevel->SetInput(image);
	windowLevel->PassAlphaToOutputOn();

	relsice->SetInput(windowLevel->GetOutput());

	actor->SetInput(relsice->GetOutput());

	FGImageActor = actor;
	FGWindowLevel = windowLevel;
	FGImageReslice = relsice;

	this->FGImageActor->SetOpacity(0.95);

	Update();
	SetupAnnotations();

	this->GetRenderer()->AddViewProp(this->FGImageActor);	
	this->GetRenderer()->Render();
}

/////////////////////////////////////////////////////////////////////////////////////////

void vtkViewImage2D::SetResliceAxesDirectionCosines( double x0, double
x1, double x2,
													 double y0, double y1, double y2,
													 double z0, double z1, double z2 )

{
	if ( this->ImageReslice != NULL) {
		this->ImageReslice->SetResliceAxesDirectionCosines(x0,x1,x2,
														   y0,y1,y2,
														   z0,z1,z2);
	}

	if ( this->FGImageReslice != NULL) {
		this->FGImageReslice->SetResliceAxesDirectionCosines(x0,x1,x2,
															 y0,y1,y2,
															 z0,z1,z2);
	}
}

-- 
John M. Drescher