"ps: Friendly nod to Xavier for pointing out "**" syntax does "to the power of" so I don't need to use math.pow() in my code."
Ok, that's my day made worthwhile! On 2 May 2012 19:00, Alan Fregtman <[email protected]> wrote: > Hey Brad, > > I wondered if using math directly would be faster than working with > XSIMath objects, so I tried. You probably knew this, but to get a distance > between two 3D vectors the formula is quite easy: > > * d = √ (Ax-Bx)2 + (Ay-By)2 + (Az-Bz)2 > * > where A and B are two vectors to measure from. > > However, you can skip the squareroot if you're only comparing relative > distances. Squareroots can be computationally expensive. > > > Knowing this, I wrote a version which appears to run about 77% faster, and > it's shorter too! (It takes 4.5s testing a null near a 1000x1000 pointcloud > grid, vs your code taking about 20.3s on the same task.) > > def FindClosestPoint( inObj, inPos ): > fX, fY, fZ = inPos.Get2() > pts = inObj.ActivePrimitive.Geometry.Points > pos = pts.PositionArray > > d = dict( [ (i, (fX-pos[0][i])**2 + (fY-pos[1][i])**2 + (fZ-pos[2][i])**2 > ) for i in xrange(pts.Count) ] ) > closestIndices = sorted(d, key=d.get) > > # distance = d[closestIndices[0]]**0.5 > return closestIndices[0] > > > > I love me a Python optimization challenge. :) > Cheers, > > -- Alan > > > > ps: Friendly nod to Xavier for pointing out "**" syntax does "to the power > of" so I don't need to use math.pow() in my code. > > > On Tue, May 1, 2012 at 5:55 PM, Bradley Gabe <[email protected]> wrote: > >> Sure, have at it: >> >> def FindClosestPoint( inObj, inPos): >> dist = 10000 >> ID = -1 >> Pos = XSIMath.CreateVector3() >> PosArr = inObj.ActivePrimitive.Geometry.Points.PositionArray >> for index in range(inObj.ActivePrimitive.Geometry.Points.Count): >> Pos.Set( >> PosArr[0][index], >> PosArr[1][index], >> PosArr[2][index] >> ) >> Pos.SubInPlace(inPos) >> D = Pos.Length() >> if D < dist: >> dist = D >> ID = index >> return ID >> >> >> >> >> On Tue, May 1, 2012 at 5:52 PM, Alan Fregtman <[email protected]>wrote: >> >>> Care to share a sample snippet? Maybe there are even faster ways to >>> approach it. >>> >>> >>> On Tue, May 1, 2012 at 5:42 PM, Bradley Gabe <[email protected]> wrote: >>> >>>> UPDATE: >>>> >>>> All things considered, it's not too horrible simply looping through >>>> every position from the Geometry.Points.PositionArray, and comparing the >>>> distance in order to find the closest point in the cloud. So far, that >>>> technique is faster than anything else I've attempted to cook up. >>>> >>>> -Bradley >>>> >>>> >>>> On Tue, May 1, 2012 at 3:01 PM, Bradley Gabe <[email protected]>wrote: >>>> >>>>> Nah, it was raising errors when I tried it before starting this >>>>> thread, and it still is now [?]: >>>>> >>>>> # ERROR : 2028 - Traceback (most recent call last): >>>>> # File "<Script Block >", line 2, in <module> >>>>> # obj.ActivePrimitive.Geometry.GetClosestLocations([0, 0, 0]) >>>>> # File "<COMObject <unknown>>", line 2, in GetClosestLocations >>>>> # COM Error: Invalid argument specified. - [line 2] >>>>> >>>>> >>>>> On Tue, May 1, 2012 at 2:58 PM, Bradley Gabe <[email protected]>wrote: >>>>> >>>>>> I was going by the following quote from the docs: >>>>>> >>>>>> Note: Point locators are currently only supported by NurbsSurfaceMeshand >>>>>>> PolygonMesh objects. >>>>>> >>>>>> >>>>>> But I'll still give it a shot... >>>>>> >>>>>> >>>>>> On Tue, May 1, 2012 at 2:54 PM, Stephen Blair < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> But doesn't a PointCloudGeometry support GetClosestLocations? Can >>>>>>> you use that (I didn't try it yet) ? >>>>>>> >>>>>>> >>>>> >>>> >>> >> >
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