[vtkusers] Problem with color and shading when rendering vtkimagedata

[shadab anwar]

Hi Aron,
Thanks for your reply.
I am not using any specific example.

I am trying to render voxels using imagedata, I have used the above code
for doing so.
The problem I am facing is that whenever I rotate the image after rendering
I don't get proper shading and uniform coloring. Instead, I am getting
above rendering results, where you can see the few voxels are shaded as
black!
I am not able to understand where I am going wrong. I tried changing
few shading and lighting parameters but no success.

I am a newbie, apology If my problem is too basic!


On Wed, Dec 12, 2018 at 4:06 PM Aron Helser <aron.helser at kitware.com> wrote:

> Can you be more specific? How do the images differ from what you expect?
> Is there are particular VTK example you are following that you are trying
> to change?
> https://lorensen.github.io/VTKExamples/site/Cxx/
>
> Aron
>
> On Wed, Dec 12, 2018 at 1:40 PM shadab anwar <sk.shadabanwar at gmail.com>
> wrote:
>
>> Guys,
>> Waiting for reply!
>>
>> Please help!
>>
>>
>>
>>
>> On Wed, Dec 5, 2018 at 2:08 PM shadab anwar <sk.shadabanwar at gmail.com>
>> wrote:
>>
>>> Hey amigos,
>>>
>>> VTK noob here!
>>>
>>> I facing a few problems while rendering vtkimagedata. The code snippet
>>> as follows,
>>>
>>>
>>>  int X =4, Y=4, Z=4;
>>>
>>>        imageData->SetDimensions(X,Y,Z);
>>>
>>>        imageData->SetSpacing(1,1,1);
>>>
>>>        imageData->AllocateScalars(VTK_INT,1);
>>>
>>>
>>>
>>>  for (int k = 0; k < Z ; k++)
>>>
>>>        {
>>>
>>>            for (int j = 0; j < Y ; j++)
>>>
>>>            {
>>>
>>>                for (int i = 0; i < X ; i++)
>>>
>>>                {
>>>
>>>                    int* voxel = static_cast<int*>(imageData->GetScalarPointer(i, j, k));
>>>
>>>                       voxel[0] = 10;
>>>
>>>
>>>                }
>>>
>>>            }
>>>
>>>        }
>>>
>>>
>>>  for (int i=2;i!=-1;i--)
>>>
>>>        {
>>>
>>>        int* voxel = static_cast<int*>(imageData->GetScalarPointer(2,i,i));
>>>
>>>         voxel[0]=0;
>>>
>>>         }
>>>
>>>
>>>     mapper->SetBlendModeToComposite();
>>>
>>>      mapper->SetRequestedRenderModeToRayCast();
>>>
>>>       mapper->SetInputData(imageData);
>>>
>>>      compositeOpacity->AddPoint(10,1);
>>>
>>>       color->AddRGBPoint(10,1,0,0);
>>>
>>>      compositeOpacity->AddPoint(0,0);
>>>
>>>        color->AddRGBPoint(0,0,0, 0);
>>>
>>>        volumeProperty->SetAmbient(0.3);
>>>
>>>         volumeProperty->SetDiffuse(0.4);
>>>
>>>         volumeProperty->SetSpecular(0.8);
>>>
>>>        volumeProperty->SetInterpolationType(0);
>>>
>>>         volumeProperty->ShadeOn();
>>>
>>>         volumeProperty->SetColor(color);
>>>
>>>          volumeProperty->SetScalarOpacity(compositeOpacity);
>>>
>>>           renderer->SetBackground(0.5, 0.5, 0.5);
>>>
>>>         volume->SetMapper(mapper);
>>>
>>>         volume->SetProperty(volumeProperty);
>>>
>>>         renderer->AddViewProp(volume);
>>>
>>> I am getting the below results,
>>>
>>>
>>> [image: image for forum.jpg]  [image: image for forum2.jpg]
>>> [image: image for forum3.jpg]
>>>
>>>
>>> It can be seen that everytime I rotate my image I don't get a proper
>>> shading and color for the object. I have tried changing the lightining
>>> properties and shading properties but no sucess.
>>>
>>> I would be really thankful if anyone could help me.
>>>
>>>
>>> Just for your information I am mechanical engineering with a bit of programming knowledge, so if my question is irrattional please forgive me.
>>>
>>>
>>>
>>>
>>> Best,
>>>
>>> Shadab
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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