CODEWITHSUNDEEP
3dvtk
Si Ling
Si Ling

Reputation: 55

VTK: What does setExtent, setOrigin, setSpacing means in a 3D image?

I understand that this can be a very basic VTK image processing question. After reading api documentation, I can't fully comprehend the idea.

My question: What does setExtent, setOrigin and setSpacing means in a 3D image using vtkImageData ?

Position_in_space_point = origin + spacing. Then why do we need to setExtent?

From http://www.vtk.org/doc/nightly/html/classvtkImageData.html#a08f18365c7178f8f595b08403db27a55, it says that setExtent is defined by the first and last point on each axis. Am I missing something?

Thank you :)

Upvotes: 4

Views: 2952

Answers (1)

JohnnyQ
JohnnyQ

Reputation: 1611

These settings specifies the dimension and position of your vtkImageData object.

SetExtent sets the dimensions in each axis. e.g. a dataset of 50 images and width/height of 512/512

myVtkImageData->SetExtent(0,511,0,511,0,49);

SetSpacing sets the size of a voxel (size in each direction x,y,z) in your dataset.

(default)

myVtkImageData->SetSpacing(1,1,1);

SetOrigin sets the position in 3D space of point 0 0 0 (first pixel)

(default)

myVtkImageData->SetOrigin(0,0,0)

Upvotes: 4

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