meshsmooth Posted February 1, 2007 Share Posted February 1, 2007 first why... I am working on creating a way to analyse the curvature of a surface and find its maxim and minim curvature angles. i plan to scatter points across the surface and compare there positions to determine the curvature and then point the normal down hill. but then all I realy want is.... I have fumbled about but am yet to find a solid example of a VOP sop using Point clouds beond using the pcfilter VOP. I have made a file that is simple and not even attempting to deal with the curvature of the surface yet. but it would be. a good place to show off how to use point clouds in VOPs beond the pcfilter VOP. so anybody up for a little point cloud starter file for VOP users? Thanks in advanced Robert. point_cloud_vop.hip Quote Link to comment Share on other sites More sharing options...
Andz Posted February 1, 2007 Share Posted February 1, 2007 Hi Mesh, sorry for not being much of a help, but how do you intend to measure a radius with a point cloud? I only ask this because I've anaysed min and max radius of surfaces, slopes, etc... for the longest time, but in other software. Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted February 1, 2007 Share Posted February 1, 2007 Hey Mesh, Just a quick note in case you weren't aware: Luca ('doc' here at odforce) posted a set of hipfiles demonstrating point clouds to the Exchange. I'm pretty sure he used VOPs for some of the examples (if not all). Check them out if you haven't already. Cheers! Quote Link to comment Share on other sites More sharing options...
meshsmooth Posted February 2, 2007 Author Share Posted February 2, 2007 i wont be mesureing all that much just pointing a normal in the direction of most chainge. this is a axis in 2 directions so i will always choose the "down hill" option. i havent got far enough to know what will work but i will start with mesuring the points around each point and compare there dot product with the normal of the quired point. a flat surface should have a dot product of 0 between its nebouring points and its normal. so the vector to the sourounding point samples are multplyed by there dot product with the normal so the vectors that grow are the ones with the larger curvature. or something like that. but when i get back onto it i will work it out. Quote Link to comment Share on other sites More sharing options...
Andz Posted February 2, 2007 Share Posted February 2, 2007 Can you measure the angle between two normals? Quote Link to comment Share on other sites More sharing options...
MIguel P Posted February 2, 2007 Share Posted February 2, 2007 (edited) Hey Mario, thank you for the link, very useful! Edited February 2, 2007 by MIguel P Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted February 2, 2007 Share Posted February 2, 2007 hi andz, you can use this to find an angle between 2 normal. acos(dot(normalize(vector3($NX, $NY, NZ)), normalize(vector3($NX2, $NY2, $NZ2)))) HTH, Alex Quote Link to comment Share on other sites More sharing options...
Andz Posted February 5, 2007 Share Posted February 5, 2007 you can use this to find an angle between 2 normal.acos(dot(normalize(vector3($NX, $NY, NZ)), normalize(vector3($NX2, $NY2, $NZ2)))) HTH, Alex Thank's Alex! Mesh, does that help you? Larger angle between two neighbor points = bigger curvature. Quote Link to comment Share on other sites More sharing options...
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