Marc Posted June 23, 2016 Share Posted June 23, 2016 (edited) Does anyone have any nifty tricks to discover why light is leaking out of a closed object? I'm modeling a building with an area light inside and some light is escaping from the building! I've checked all the points (fused status), primitive normals, etc. and it all looks good, I've also checked for intersecting polys, but there are none that I can see. Obviously something is wrong though . edit: I replaced my beautiful model with a cube and light still leaks through. Now I'm doubly confused. Thanks M Edited June 23, 2016 by Marc Quote Link to comment Share on other sites More sharing options...
Atom Posted June 23, 2016 Share Posted June 23, 2016 (edited) I just gave your test a try. I created a cube 3 units large and placed it above a grid ground plane. I put an area light inside the cube. Without a material applied I do see a hot spot on the sides of the cube and some light is leaking out and lighting the ground plane. However, when I applied a Mantra Surface (alternately a Principled shader) the hot spot diminished drastically. But I still noticed some light leak. If you turn down the exposure on the light that does help a lot, I reduced my exposure down to 1.0 from 5.5. I also turned off Normalize Light Intensity to Area and made the light single sided. With those changes that gave me essentially a black scene. You can setup lights inside the Mantra node to isolate certain objects to receive or not receive light but it does seem like a "sealed" objects should contain all light and not leak. Edited June 23, 2016 by Atom Quote Link to comment Share on other sites More sharing options...
jkunz07 Posted June 23, 2016 Share Posted June 23, 2016 Have you tried adjusting the raytracing bias? 1 Quote Link to comment Share on other sites More sharing options...
bandini Posted June 23, 2016 Share Posted June 23, 2016 Does it still happen if the area light is single sided? Quote Link to comment Share on other sites More sharing options...
MENOZ Posted June 23, 2016 Share Posted June 23, 2016 (edited) I tried with a box, arealight inside and I also can see the borders of the box illuminated. A normal sop on the box seems to fix the problem anyway. EDIT: light still leaks on an exterior plane, and the box itself looks good as long as the object scale stays to 1. I can scale the box from SOP and still looks fine, but as soon as i scale it from obj level it starts to get light artifacts. using a matra surface seems to fix the problem of light leaking for me as well. If the box intersect the plane there's the border due to the raytracing bias. Edited June 23, 2016 by MENOZ Quote Link to comment Share on other sites More sharing options...
Marc Posted June 24, 2016 Author Share Posted June 24, 2016 Hey guys A lot of things to go through: raytracing bias doesn't improve it at all isolating the light to only affect certain things won't work since I want the light to come through the windows and illuminate the environment, just not also out of the back wall, the floor, the roof and every other thing it feels like coming out of single sided light does nada shaders help a little, but not enough to fix the problem For the cube test, I took the bounds of the model and then polyextruded all the polygons to simulate walls (and confirmed the primitives were all facing in the right direction) and it still leaks light. I'll see if I can replicate it in a simple example and upload it here. M Quote Link to comment Share on other sites More sharing options...
Marc Posted June 24, 2016 Author Share Posted June 24, 2016 Here's a file... lightleaks.hip Quote Link to comment Share on other sites More sharing options...
MENOZ Posted June 24, 2016 Share Posted June 24, 2016 I have no idea why it happens, I would submit it to sidefx as a bug and see what they say, if it's a bug or there's seomthing we should be aware of. anyway, if you turn on subdivision surfaces or add a normalSOP to the gridObject and use a cusp value like the default one the artifact disappear. if you set the cusp back to 180 you'll see the artifact again. 1 Quote Link to comment Share on other sites More sharing options...
rbowden Posted June 24, 2016 Share Posted June 24, 2016 Definitely agree with Andrea. This is a bug. It has to do with the way the normals are fused on the edge of your grid_object 1. Looking at the point normals on polyextrude1 and comparing it to facet SOP with unique points on, you can see the normals on the edge of the gridobject changing. Rendering this result will fix the light leaking issue. Regardless of this result and what the normals of the gridobject are, you shouldn't be getting any light being captured on it. Definitely submit this as a bug. 1 Quote Link to comment Share on other sites More sharing options...
Marc Posted June 24, 2016 Author Share Posted June 24, 2016 Yeah I've submitted it. Cusping/unique'ing the points on the receiving geo does fix it, which is unexpected. But whatever I'll just roll with that for now until I hear back from SideFX. Thanks guys M 1 Quote Link to comment Share on other sites More sharing options...
MENOZ Posted July 2, 2016 Share Posted July 2, 2016 hello, did you had any news from sidefx ? Quote Link to comment Share on other sites More sharing options...
Marc Posted July 4, 2016 Author Share Posted July 4, 2016 I sure did: Quote I submitted this as bug #76304 :) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.