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April 18th, 2019, 05:21 AM   #1
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Joined: Jul 2018
From: Germany

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Find duplicate Geometry with Linear Transform

Hey,

I'm working on an algorithm that finds duplicate Geometry. Here's what I do: I'll take a mesh, get all it's vertices and find the average of them:

x = average(a, b, c, d, e, f)

then I'll get the distances of the average to the vertices:

bd = dist(x, b)
cd = dist(x, c)
dd = dist(x, d)

and now I'm sorting them and remove duplicates. so far so good, it works and is pretty stable, this list I can compare to other lists to find duplicate geometry, I'll just use 3 entrys of these lists to compare, as it's a lot faster though.

THE QUESTION:

I want to also find sets of the same base-geometry that were simply transformed linearly, see the picture attached:

here you'll see three potatoes from left to right. the first two are based on the same mesh, I've only linearly transformed them, the third one is a different mesh, or non-linear transform. Is there any way that I can find geometry that has had the same base?

The graphs above the geometries are the distances from their averages, without duplicates and sorted.

Any help is appreciated
Attached Images potatoes.jpg (13.3 KB, 2 views) April 19th, 2019, 06:26 AM #2 Member   Joined: Jul 2018 From: Germany Posts: 37 Thanks: 1 Or another question that would help me a lot: If I apply a random linear transform on an object, is there anything that stays constant? The more constants there are, the more of a base I have to operate upon. - I know the vertice-count, that helps to determine duplicates. - The distance of the closest vertice to the average is not reliable, the closest vertex might change due to the transform. If I knew the bounding box of the original, that would solve everything, because that is the basis that I use for the transform (scaling, moving, rotating), but I don't, and don't know how to get it. Getting a bounding box that stays relative to the vertices on every linear transform, can I get that somehow? Tags duplicate, find, geometry, linear, transform Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Cardigan Probability and Statistics 5 January 23rd, 2015 03:58 AM mathematicer Calculus 0 June 6th, 2014 09:54 PM elimax Linear Algebra 1 July 7th, 2011 10:11 PM

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