# jonp

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• Rank
Initiate

• Name
Jon
• Location
New York
1. ## Learn Processing before VEX?

Can you follow this with VEX? Seems like a lot of overlap with Processing:
2. ## wrangle performance when creating new points

I'm using about 1000 points in a point wrangle SOP as seeds to generate lines, totalling about 20,000,000 points... performance seems almost single threaded, which I assume is due to the creation of new geo. Is there any way I can speed it up? Here's the code in question if anything obviously jumps out: // trace lines through nested velocity volumes void stepRK4(vector pos; const int prim; const float dt; const vector V0; float dir) { vector V1 = volumesamplev(1, prim, pos + (0.5 * dt) * V0) * dir; vector V2 = volumesamplev(1, prim, pos + (0.5 * dt) * V1) * dir; vector V3 = volumesamplev(1, prim, pos + dt * V2) * dir; pos += (dt / 6) * (V0 + 2 * (V1 + V2) + V3); } void step_forward(vector pos; float dir) { float dist = length(pos); // There are volumes at 5 levels of detail, starting from the origin. This distance metric chooses which to sample from int prim = int(max(log(dist / 8. * 2) / log(4) + 1, 0)); // advection step based on the voxel size float vd = volumevoxeldiameter(1, prim); float dt = vd * 2; vector vel = volumesamplev(1, prim, pos) * dir; stepRK4(pos, prim, dt, vel, dir); } int steps = 10000; int pr1 = addprim(geoself(), "polyline", @ptnum); int pr2 = addprim(geoself(), "polyline", @ptnum); vector pos1 = @P; vector pos2 = @P; for (int i=0; i<steps; i++) { step_forward(pos1, 1); if (length(pos1) >= 1 && length(pos1) < 1000) { int newpt1 = addpoint(0, pos1); addvertex(geoself(), pr1, newpt1); } step_forward(pos2, -1); if (length(pos2) >= 1 && length(pos2) < 1000) { int newpt2 = addpoint(0, pos2); addvertex(geoself(), pr2, newpt2); } }
3. ## American Museum of Natural History, Generalist TD

AMNH in NYC is looking for a TD to fill a year long spot on our next planetarium production. See details here: https://careers.amnh.org/postings/1718 We're also potentially looking for a few modelers and Maya/Houdini lookdev artists to help develop spacecraft models and planetary elements over the course of production, and a Nuke compositor later in the summer. Staff position is on-site, and freelance gigs are preferred on-site but we could work remotely with the right person. Our shows are regularly considered among the best in the field and emphasize accuracy and making cutting edge scientific data visualization accessible to a general audience. Two examples of previous shows: https://www.amnh.org/exhibitions/space-show/dark-universe https://www.amnh.org/global-business-development/planetarium-content/passport-to-the-universe This is a very small commercial size team working on a medium length production with a reasonable schedule, which could be a nice change of pace from either commercials or film, depending on which way you look at it. The content is typically pretty technical and substance always wins over style here. The TDs often end up doing a wide range of work from camera layout, to FX, to graphics programming and Python scripting. And for you Houdini nerds, Houdini is our core production package for most content creation and rendering. Email Gavin Guerra (gguerra@amnh.org) or me at my AMNH email (jpparker@amnh.org) for more info. -Jon
4. ## Juraj's playground

Juraj, Great tips! I'm curious about your volume baking post. How did you approach that? Cheers, Jon
5. ## custom volume plugin q. -- vary step size?

Greetings, I'm looking into visualizing some scientific simulations that either use 3D voronoi tessellation or are adaptive mesh refinement simulations. I would like to vary the "volume quality" parameter based on the local resolution of the adaptive volume. Before delving into the HDK to accommodate this: is it possible? Cheers, Jon

COPS?
7. ## Fancy font tools?

Hello SOPpers, Are there any slightly more advanced font tools for Houdini floating around the internet? I'm looking for Illustrator style tools that will let one have fonts follow a path and also maintain distances and shape, etc.. Extrusion and beveling tools aren't needed for what I'm doing now but it could be useful in the future. Basically a Font tool for motion graphics. I can always roll my own version but it sounds useful enough that someone else has already done it. Cheers, Jon
8. ## Merge edit sops?

Yes, that's excellent! Thanks!
9. ## Merge edit sops?

Is there some secret function or script that will let me merge multiple edit SOP operations into one node? I'm not seeing a big performance hit with lots of them chained together but... OCD is kicking in.
10. ## Python's multiprocessing

I'm having issues with multiprocessing as well, on Linux, where my child processes don't seem to do any work when the script is run in Houdini. set_executable() doesn't exist on Linux so I'm wondering if there is anything else I can do to try to fix it? -Jon
11. ## Random link of interest

The largest virtual universe ever simulated: https://phys.org/news/2017-06-largest-virtual-universe-simulated.html 2 trillion particles! https://link.springer.com/article/10.1186/s40668-017-0021-1
12. ## interoplate point data into volume using radial basis functions?

EDIT: Given that RBF is in fact used in mesh deformation, I should clarify that I'm interested in using it to convert particle simulations into volumess.
13. ## interoplate point data into volume using radial basis functions?

Maybe I know just enough to not know anything about this... I was reading about radial basis function interpolation and in sample images it gives a really nice smooth result and seems to more intelligently fill in missing values than some other methods. However, it sounds like it takes a ton of memory to perform and is quite slow. Has anyone experimented with it? I've tested the Scipy implementation, which very rapidly runs out of memory and makes it impossible to use for real-world sized data. Cheers, Jon