Scott Peterson
scottp
About Me
Machine Learning Graphics developer at Unity.
EXPERTISE
Technical Director
INDUSTRY
Film/TV
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LOCATION
United States
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Houdini Skills
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Not Specified
Recent Forum Posts
High DPI screen and normal DPI dual screens, how to make UI scaling consistent Dec. 29, 2020, 2:03 p.m.
This is still an issue in 18.5. I would like to be able to use Houdini on both monitors, but I'm not able to read both comfortably. Can Houdini just detect the high DPI screen, and automatically scale on only that screen?
Volume Analysis Terrain Curvature July 21, 2020, 9:36 p.m.
I found a way to replicate curvature, in case anyone needs this. Curvature is basically planform curvature, or horizontal curvature in GIS systems. Planform curvature relates to the convergence and divergence of flow across a surface.
float s = ch("../heightfield1/gridspacing"); // https://www.microimages.com/documentation/TechGuides/70CurvScript.pdf float z1 = volumesample(0, 0, @P + set(-s, 0, -s)); float z2 = volumesample(0, 0, @P + set(0, 0, -s)); float z3 = volumesample(0, 0, @P + set(s, 0, -s)); float z4 = volumesample(0, 0, @P + set(-s, 0, 0)); float z5 = volumesample(0, 0, @P + set(0, 0, 0)); float z6 = volumesample(0, 0, @P + set(s, 0, 0)); float z7 = volumesample(0, 0, @P + set(-s, 0, s)); float z8 = volumesample(0, 0, @P + set(0, 0, s)); float z9 = volumesample(0, 0, @P + set(s, 0, s)); float a2 = (z4 + z6) / (2 * s * s) - z5 / (s * s); float b2 = (z2 + z8) / (2 * s * s) - z5 / (s * s); float c = (z3 + z7 - z1 - z9)/(4 * s * s); float d2 = (z6 - z4)/(2 * s); float ee2 = (z2 - z8)/(2 * s); float plndenom2 = pow(ee2*ee2 + d2*d2, 1.5); // @height = -2 * (a * (d * d) + b * (ee * ee) + c * d * ee); // Plan curvature (better) // @height = -2 * (b * (d * d) + a * (ee * ee) - c * d * ee) / plndenom; @height = -2 * (b2 * (d2 * d2) + a2 * (ee2 * ee2) - c * d2 * ee2) / plndenom2; @height *= -1; @height = clamp(@height, -5, 5);
Volume Analysis Terrain Curvature July 21, 2020, 3:46 p.m.
I like the results of the curvature volume analysis that the “Heightfield Mask By Feature” computes when applied to a heightfield. Under the hood (i.e. “Allow Editing of Content”), I noticed Heightfield Mask By Feature uses the volume analysis SOP, measuring the curvature of the surface. I'd like to do something similar in a shader outside of Houdini.
There's a lot of online documentation about how laplacian is computed from a simple convolution of weightsbut I can't figure out how Houdini is computing curvature. Can someone shed some light on the way that houdini computes volume curvature? VDB curvature is computed differently than the volume analysis curvature, otherwise I could just inspect the OpenVDB code.
I've also tried to use the differential edge detection technique described here without success: https://en.wikipedia.org/wiki/Edge_detection [en.wikipedia.org] (Differential)
There's a lot of online documentation about how laplacian is computed from a simple convolution of weights
[[1,1,1], [1,-8,1], [1,1,1]]
I've also tried to use the differential edge detection technique described here without success: https://en.wikipedia.org/wiki/Edge_detection [en.wikipedia.org] (Differential)