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Computer Graphics

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  • $\begingroup$ But if the model is centered around the center (0,0,0) in a unit cube, is there really a need for rescaling points back to the unit cube? Moreover, can I use the same rotation matrix for normals as I used for points? $\endgroup$ Commented May 4, 2020 at 1:26
  • $\begingroup$ also, I don't like your approach by scaling by maximum value across all axises (x,y,z), since it degrades pointcloud objects significantly. Say you have a pencil like object, if you scale it by it's maximum value, which is surely going to be along the pencil length, and divide both it's width and height by the same value, you will get something that looks more like a small radius stick than the pencil. $\endgroup$ Commented May 4, 2020 at 11:32
  • $\begingroup$ Question 1: Depends on your model. But take the unit cube itself as an example. If you rotate it by any angle that isn't a multiple of 90 degrees, The corners will end up outside the unit cube. To visualize it, take two dice and put them on top of each other so that they are aligned. Now rotate the upper one by 45 degrees. See the problem? Only if all your points are initially inside the unit sphere, you can be sure that no point will end up outside the unit cube after an arbitrary rotation. $\endgroup$ Commented May 4, 2020 at 12:09
  • $\begingroup$ Also, why scaling by some value, it's rotation and should be shape and length preserving, wouldn't shifting/translation be correct way of bringing object back to the unit cube? $\endgroup$ Commented May 4, 2020 at 12:11
  • $\begingroup$ Question 2: Yes, actually you HAVE to, otherwise you get wrong normals. A quote from my answer: "Normals are rotated the same way as the rest of your mesh/point cloud." $\endgroup$ Commented May 4, 2020 at 12:13