chippwalters
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HEX displacement decimation strategy
🕑 Added 2022-01-13 14:26:25 +0000 UTCSo if you look at these renderings you may not recognize anything of great interest. Then, look closely at the wires and you'll see the hex patterns are fairly cleanly modeled faces in Blender. Included in these images is a tilable hex PNG that I created and used as a displacement map in order to create the hex modeled object. As many of you know, in order to get a really tight displacement like this, you need an extremely dense mesh. So, that doesn't necessarily match with what you're seeing in the wires.
Then, how did I work my way from a 4 million vertice model down to the simplified model you see here? It's one of the strategies I've been working on as I've been creating my displacement generator. In other words, how to create the smartest decimation possible?
The recipe for this object is below. I started with the square default plane and I added a Subdivision Surface modifier set to Simple and then added a Displace modifier and made sure that I mapped the Displace modifier to the UVs of the plane and then in the UV editor I scaled the plane up considerably so that it would tile many times. I typically do this in RGB and not displaced mode so I can get it exactly the way I want and then I will switch to displacement and adjust the offset at that time and remove the RGB mapped image. Typically I will tweak the number of vertices by adjusting the Subdivision Surface modifier.
I have found that I can speed up the Limited Dissolve or Planar decimation by dividing up the surface in quadrants after applying the modifiers. I believe this speeds up the decimation by a factor of four or more. I then join the mesh together after the first lengthy Limited Dissolve decimation, and then the following Welds and Decimation modifiers take place in the sequence as described below.
As previously mentioned, the first decimation is done in edit mode using the Limited Dissolve mesh clean up command, and this is so that it only needs run once. Limited Dissolve is the exact same as the Decimate modifier set to Planar. The only issue is that with a modifier it has to run once and then you have to apply it so it runs a second time. Whereas when you're in edit mode you need only run it one time.
I typically save after every step just to make sure I don't make any mistakes because if you press the wrong button or accidentally make a mistake early on it can take a long time to get back to where you left off.
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Good for <4M Verts
*** MAKE SURE YOU'RE USING WIREFRAME VIEW! ***
1. Divide mesh into 4 objects by going into edit mode, box select half, separate by selected, tab into object mode, tab back into edit mode (for both objects) and select half again and separate by selected.
2. Check to make sure you have 4 distinct objects!
3. With all 4 objects selected, tab back to object mode and then back to edit mode. Now you will be editing 4 objects in edit mode.
4. Press A to select All faces and then select: menu > Mesh > Clean Up > Limited Dissolve at default 5 degrees. Will take about 20 minutes or longer!
5. Save. Then Join all 4 objects into 1
6. Edit full mesh by side view and set all verts on top 1/4 to coplanar and then on bottom 1/4 to coplanar (scale Z = 0)
7. Add a Weld modifier set to .001
8. Add a Decimate modifier using .1
9. If it took a lot of time, then apply before going on to next step
10. Add another Decimate modifier this time choose Planar at 5 degrees
11. Weld modifier set to .004 (or adjust to what looks right) to clean up
I difference Booleaned a cylinder to create the round shape. The small edge bevels are rendered bevels and Cycles.
Comments
Kyle F
OMG this has answered what I have been trying to figure out for a couple weeks now. This will work awesome on the honeycomb effect on tie fighter wings, that area in the inside and outside of the classic version.
Justin Jacobs
Very nice! Video Tutorial on this? The object looks like many of the Sport Car "Fog Light" covers (though the hexes were not as deep on those). Maybe only 5-6mm deep if that I think. The purpose was they could be "Removed" for added air flow into the Cold Air Intakes and or actually be removed for "Real Fog Lights or LED's"
Chipp Walters
Yeah, I probably need to do a tutorial as now that I reread it it is fairly complex. Haha
Valics Lehel
you can do this grids for photography light reshaper :-)
Richard Osborn
Thanks for the excellent explanation Chipp. I wish I'd known about this a few years ago when I did some speaker renders for a client (Martin Audio, here in the UK). My method was far more complex! Any chance of a quick video tut for this method?
