Render RGB-D image from mesh

Question

I have a mesh model (.ply file) and I have rendered it with VTK and changed the camera viewpoint.

From the new camera viewpoint how can I render an RGB and a depth image? I think this might be raytracing, but not sure

EDIT

I want to generate a real depth map, as opposed to just a visualization of the depth. The visualization can be achieved by using values in Z buffer and scaling between 0-255 but this does not provide real depth information.

Answer 1

To get the real world depth from the camera I have done the following:

double z = render_win->GetZbufferDataAtPoint(x,y);
worldPicker->Pick(x, y, z, renderer);
worldPicker->GetPickPosition(coords);
double euclidean_distance = sqrt(pow((coords[0] - cam_pos[0]), 2) + pow(coords[1] - cam_pos[1], 2) + pow(coords[2] - cam_pos[2], 2));

where cam_pos is the camera position in real world coordinates. This seems to do the trick

Answer 2

Here is a short few lines if you already have the application set up and rendering, this has to be after the mesh has rendered at least once

// Screenshot  
vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter = 
vtkSmartPointer<vtkWindowToImageFilter>::New();
windowToImageFilter->SetInput(renderWindow);
windowToImageFilter->SetMagnification(3); //set the resolution of the output image (3     times the current resolution of vtk render window)
windowToImageFilter->SetInputBufferTypeToRGBA(); //also record the alpha (transparency)   channel
windowToImageFilter->Update();

vtkSmartPointer<vtkPNGWriter> writer = 
  vtkSmartPointer<vtkPNGWriter>::New();
writer->SetFileName("screenshot2.png");
writer->SetInputConnection(windowToImageFilter->GetOutputPort());
writer->Write();

This is from the VTK Public Wiki