Rotate object based on oriented bounding box

[konstantin magnus]

I put a slightly oblique scanned object into an oriented bounding box and picked two points that are supposed to be straight. Now I am struggling to counter-rotate my mesh according to the bounding box´s orientation.

vector scan_orient = normalize( point(0, "P", 0) - point(0, "P", 3) );
vector straight = {0, 0, 1};

matrix3 rot = dihedral(scan_orient, straight);
rot = invert(rot);
@P *= rot;

What am I missing?

Edited February 5, 2018 by konstantin magnus

[f1480187]

That given orientation is not the optimal to align two vectors. Consider you aligning a geo to same geo rotated by 180 degrees around Y axis using edge looking straight UP. There wouldn't be any transform (vectors already pretty aligned), but orientations are vastly different. dihedral won't help there. I would build a proper basis using at least 3 points here.

[konstantin magnus]

@f1480187 Okay, then let´s assume I took two or three vectors along the edges of my oriented bounding box like this:

vector scan_x = normalize( point(0, "P", 0) - point(0, "P", 3) );
vector scan_y = normalize( point(0, "P", 0) - point(0, "P", 1) );
vector scan_z = normalize( point(0, "P", 0) - point(0, "P", 4) );

Whats the most direct way to turn this into a matrix that actually rotates my object back in place?

Edited February 5, 2018 by konstantin magnus

[f1480187]

@P *= set(scan_x, scan_y, scan_z);

The scan_* axes in the snippet above are negative though, I would swap operands. If axes are incorrect, try different combinations of 3-1-4. E.g.: 1-4-3.

[vinyvince]

It's in a way related to my question there

https://www.sidefx.com/forum/topic/80359/?page=1#post-345366

 

Edited August 16, 2021 by vinyvince

[vinyvince]

is there no way to automate the permutations and pick the right one?

 

 

 

 

Edited August 16, 2021 by vinyvince