[osg-users] Volume rendering issues...

[Tom Williamson]

Hi gang,

Thanks for all the work on OSG, is rad. I'm currently having a problem with the rendering of a volume, here's what I'm trying to do:
- I'm using ITK to read a NIFTI file, (segmentation of a bone). The file contains zeros (background) and ones (object), format is unsigned short. 
- I am then normalizing/scaling this and converting it to an osg::Image.
- I am then attempting to convert this to an osgVolume and display an iso-surface, or at this stage any kind of volume rendering.
- All the reading, conversion etc. seems to work okay, but I'm getting a read access violation on line 408 of Texture3d.cpp (specifically:Exception thrown at 0x00007FFE64D576B0 (ig9icd64.dll) in RobotSimulation.exe: 0xC0000005: Access violation reading location 0x000002F5732EE070.)

I'm pretty sure I'm just forgetting something very obvious, but if anyone could point out what it is that I'm doing wrong that would be much appreciated. I've put a cut down example of the code below (pretty rough).
I know that the data is definitely in the osg::image object (wrote it to file, calculated min and max), so I don't necessarily think the conversion is the problem (though could very well be wrong). I'm on a Windows 10 laptop, with a built in Intel graphics card (Intel HD Graphics 620, drivers are up to date), opengl is version 4.5.
Thanks very much for the help, let me know if you need any other info. Cheers,
Tom

PS: I'm happy to provide some example data if needed, but I guess this would be more or less the same for any data loaded through ITK and converted to OSG.
PPS: I've left the code as normal text, it looked somewhat unreadable in the preview, so sorry about that.

[code]
osg::ref_ptr<osgVolume::Volume> getOsgVolume(std::string filename)
{
	osg::ref_ptr<osg::Image> osgImage = new osg::Image();
	itk::NiftiImageIOFactory::RegisterOneFactory();
	itk::ImageIOBase::Pointer imageIO = itk::ImageIOFactory::CreateImageIO(filename.c_str(), itk::ImageIOFactory::ReadMode);
	imageIO->SetFileName(filename);
	imageIO->ReadImageInformation();
	osg::ref_ptr<osgVolume::Volume> volume = new osgVolume::Volume;

	std::cout << "numDimensions: " << imageIO->GetNumberOfDimensions() << std::endl;
	std::cout << "component type: " << imageIO->GetComponentTypeAsString(imageIO->GetComponentType()) << std::endl;
	std::cout << "pixel type: " << imageIO->GetPixelTypeAsString(imageIO->GetPixelType()) << std::endl;

	if (imageIO->GetNumberOfDimensions() == 3) {
		typedef itk::Image<unsigned short, 3>  imType;
		typedef itk::ImageFileReader<imType> imTypeReader;

		imTypeReader::Pointer imageReader = imTypeReader::New();
		imageReader->SetFileName(imageIO->GetFileName());
		imageReader->Update();

		imType::RegionType region;
		imType::IndexType start;
		imType::SizeType size;

		for (int i = 0; i < imageIO->GetNumberOfDimensions(); ++i) {
			start[i] = 0;
			size[i] = imageIO->GetDimensions(i);
		}

		region.SetSize(size);
		region.SetIndex(start);
		typedef itk::MultiplyImageFilter< imType> miType;
		miType::Pointer mif = miType::New();
		mif->SetInput(imageReader->GetOutput());
		mif->SetConstant(pow(2, 16) - 1);
		mif->Update();
		imType::Pointer itkImage = mif->GetOutput();
		region = itkImage->GetBufferedRegion();
		size = region.GetSize();
		start = region.GetIndex();

		unsigned int width = size[0];
		unsigned int height = size[1];
		unsigned int depth = size[2];

		osg::RefMatrix* matrix = new osg::RefMatrix;

		std::cout << "width = " << width << " height = " << height << " depth = " << depth << std::endl;
		for (unsigned int i = 0; i<3; ++i)
		{
			(*matrix)(i, i) = itkImage->GetSpacing()[i];
		}

		osgImage->setImage(width, height, depth, GL_LUMINANCE16, GL_LUMINANCE, GL_UNSIGNED_SHORT, (BYTE*)itkImage->GetBufferPointer(), osg::Image::NO_DELETE, 1, width);

		// Setup the transfer function
		osg::ref_ptr<osg::TransferFunction1D> transferFunction = new osg::TransferFunction1D;
		transferFunction->setColor(0.0, osg::Vec4(1.0, 0.0, 0.0, 0.0));
		transferFunction->setColor(0.5, osg::Vec4(1.0, 1.0, 0.0, 0.5));
		transferFunction->setColor(1.0, osg::Vec4(0.0, 0.0, 1.0, 1.0));

		// Setup the volume
		osgVolume::ImageDetails* details = new osgVolume::ImageDetails;
		details->setMatrix(matrix);
		osgImage->setUserData(details);
		matrix->preMult(osg::Matrix::scale(double(osgImage->s()), double(osgImage->t()), double(osgImage->r())));
		osg::ref_ptr<osgVolume::VolumeTile> tile = new osgVolume::VolumeTile;
		volume->addChild(tile.get());
		osg::ref_ptr<osgVolume::ImageLayer> layer = new osgVolume::ImageLayer(osgImage.get());
		layer->setLocator(new osgVolume::Locator(*matrix));
		tile->setLocator(new osgVolume::Locator(*matrix));
		tile->setLayer(layer.get());

		// Rest of this is setting up the volume rendering...
		float alphaFunc = 0.02f;

		osgVolume::AlphaFuncProperty* ap = new osgVolume::AlphaFuncProperty(alphaFunc);
		osgVolume::IsoSurfaceProperty* isop = new osgVolume::IsoSurfaceProperty(alphaFunc);
		osgVolume::SampleDensityProperty* sd = new osgVolume::SampleDensityProperty(0.5f);
		osgVolume::SampleDensityWhenMovingProperty* sdwm = new osgVolume::SampleDensityWhenMovingProperty(0.1);
		osgVolume::SampleRatioProperty* sr = new osgVolume::SampleRatioProperty(1.0f);
		osgVolume::SampleRatioWhenMovingProperty* srwm = new osgVolume::SampleRatioWhenMovingProperty(0.1);
		osgVolume::TransparencyProperty* tp = new osgVolume::TransparencyProperty(1.0);
		osgVolume::TransferFunctionProperty* tfp = new osgVolume::TransferFunctionProperty(transferFunction.get());
		osgVolume::CompositeProperty* cp = new osgVolume::CompositeProperty;
		cp->addProperty(sr);
		cp->addProperty(tp);
		cp->addProperty(isop);
		cp->addProperty(sdwm);
		cp->addProperty(tfp);

		layer->addProperty(cp);
		tile->setVolumeTechnique(new osgVolume::MultipassTechnique);

	}
	std::cout << "Valid: " << volume.valid() << std::endl;
	return volume;

}
[/code]

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