ehsan parizi Posted September 15, 2011 Share Posted September 15, 2011 (edited) Hi all, As you can see in the attached images, I'm getting weird artifact in my texture! I don't know what's causing this, but I'm guessing it's not from my UV! because even before doing any kind of UV projection, I used a stone shader just for a test, and I had the same problem, I thought it should be because of the fact that it doesn't have a proper UV map. The other weird thing is that I don't see that problem in my viewport! Does anybody know what might be wrong? btw, right now, I'm using mantra surface shader. and my uv project's projection type is set to orthographic. Edited September 15, 2011 by ehsan parizi Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted September 15, 2011 Author Share Posted September 15, 2011 (edited) Ok, seems like the VOP SOP that produces the noise in XZ plane is kinda causing this problem! It's weird because if I wire my uv project before that vop sop, the texture will be deformed after that vopsop, which makes perfect sense, but I don't get it why it doesn't work when my uv project is after my vop sop?! On a related subject, does anyone know how to make a procedural asphalt shader? ( I know, it's not that easy, but at least if you can tell me where to start to move in the direction, that would be awesome ) Edited September 15, 2011 by ehsan parizi Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted September 17, 2011 Author Share Posted September 17, 2011 (edited) So, nobody had any answer for my question, and I guess that because it seems to be a bug in mantra micropolygon rendering engine. As I mentioned earlier, and you can see in the attached file, the view port shows the texture properly, and I have no problem when I use the render region tool,( even when my mantra is set to micropolygon engine) BUT when I render the full image, I get the same crappy result! Anyway, after a few hours of testing different things to figure out what's causing the problem, it seems like that there's something wrong with tessellation in micropolygon engine! what I'm doing right now is using Raytrace, btw PBR gives a good result too. My Houdini version is 11.1.22, and it's an educational edition! Edited September 17, 2011 by ehsan parizi Quote Link to comment Share on other sites More sharing options...
symek Posted September 17, 2011 Share Posted September 17, 2011 It's not a bug but rather reyes sensitivity to discontinuous derivatives. Mantra in micro-polygon node needs to know primitives' space to compute sensible derivatives. Ray tracers shoot rays to whatever they see like a dumb instead . Turn on render time subdivision to allow Mantra smooth out your polygons, as I guess, messed up with VopSop, or make sure your topology is correct (no crossing edges, overlapping vertices etc). Usually render time subdivision deals with such cases well. hth, skk. Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted September 17, 2011 Author Share Posted September 17, 2011 It's not a bug but rather reyes sensitivity to discontinuous derivatives. Mantra in micro-polygon node needs to know primitives' space to compute sensible derivatives. Ray tracers shoot rays to whatever they see like a dumb instead . Turn on render time subdivision to allow Mantra smooth out your polygons, as I guess, messed up with VopSop, or make sure your topology is correct (no crossing edges, overlapping vertices etc). Usually render time subdivision deals with such cases well. hth, skk. Thanks ssk! Well, doesn't region render tool use micropolygon to render when my mantra node's rendering engine is micropolygon??! if it DOES, then why does is have no problem with my geometry? anyway, thanks for your answer, and I will try the smooth polygon just to see if it works! one more thing is that my geometry is clean, I did use vop sop to create noise but there are no overlapping vertices, although like I said before, that vopsop is creating the problem but even when I give it a very small frequency and make it smooth to create just big waves, it still has the same problem! Quote Link to comment Share on other sites More sharing options...
symek Posted September 17, 2011 Share Posted September 17, 2011 Both render region and IPR uses ray tracing even for micropoly ROP if "Preview" option is turned on (progressive rendering). Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted September 18, 2011 Author Share Posted September 18, 2011 here's the result that I get from turning on the polygon as subdivisions for mantra. this next one is micropolygon without subdivision : and this last one is raytrace Quote Link to comment Share on other sites More sharing options...
symek Posted September 18, 2011 Share Posted September 18, 2011 Add CreaseSOP/crease value = 10. Quote Link to comment Share on other sites More sharing options...
ehsan parizi Posted September 19, 2011 Author Share Posted September 19, 2011 Tried crease sop, it didn't help either! thanks for your answers though Raytrace gives me a good result, and it's pretty quick, but it's good to know how to get rid of that problem anyway! Quote Link to comment Share on other sites More sharing options...
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