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[Seg3D] 0.5 voxel offset for cursor position

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  • From: Ramón Casero Cañas <>
  • To: "" <>
  • Subject: [Seg3D] 0.5 voxel offset for cursor position
  • Date: Fri, 17 Dec 2010 21:16:03 +0000

Hi all,

Is painter_->pointer_pos_ giving the correct pointer coordinates?

Using the Spline Tool source code branch (because it allows to export seed point coordinates to a CSV file), I have noticed that if the image has, e.g.

nrrd.axis.min = [90, 162, 65]

nrrd.axis.max = [408, 396, 454]

But if you go to each of the 8 boundary slices of the image volume, the corresponding seed coordinates will be

[90.5, 162.5, 65.5]

[408.5, 396.5, 454.5]

In this case, the voxel spacing in any direction is 1.0.

The seed coordinates come from a snippet of code in like the following:

   // Add a new seed point.
    last_seed_window_ = painter_->cur_window_;
    last_seed_index_ = seeds_.size() - 1;

It seems that painter_->pointer_pos_ is offsetting the cursor position by 0.5 voxel.

Best regards,


Dr. Ramón Casero Cañas

Computational Biology
Computing Laboratory
University of Oxford
Wolfson Building, Parks Rd
Oxford OX1 3QD

tlf     +44 (0) 1865 283575

  • [Seg3D] 0.5 voxel offset for cursor position, Ramón Casero Cañas, 12/17/2010

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