kurisutofu Posted July 28, 2011 Share Posted July 28, 2011 Hello, To try the procedural modeling in Houdini, I've created a geometry that builds a pyramid out of an object I give in input (here a glass cube with a colored cube inside) with any number of rows I set. That works well for the modeling itself and for my test, my pyramid has 7 rows. I rendered with PBR, a distant light and a caustic light with 1 000 000 points. After rendering, I could see the light at the base of the pyramid is wrong ... I attach a picture so you can see it too. If you look closer under the pyramid, there are some light in the shadows of the cubes. What can I do to fix all that? I tried moving the light but it didn't help much ... Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted July 28, 2011 Share Posted July 28, 2011 After rendering, I could see the light at the base of the pyramid is wrong ... Can you describe what you're seeing as wrong please? Quote Link to comment Share on other sites More sharing options...
old school Posted July 28, 2011 Share Posted July 28, 2011 Shadow bias issue? I see bad shadows in and around the stacked boxes as well. Try adjusting the shadow bias either up or down to pull the shadows in or out of the surface. I am guessing when I say try going larger. Looks like a shadow bias issue with two surfaces that are very close together or intersecting. If the floor is a flat plane, try extruding it in to a volume. Doesn't have to be too thick. Helps with shadows on flat surfaces. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted July 29, 2011 Author Share Posted July 29, 2011 Can you describe what you're seeing as wrong please? If you look at the shadow under the cube closest to the camera on the lowest row, at the corner, you will see some light. I think the shadow should be a plain square. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted July 29, 2011 Author Share Posted July 29, 2011 (edited) Shadow bias issue? I see bad shadows in and around the stacked boxes as well. Try adjusting the shadow bias either up or down to pull the shadows in or out of the surface. I am guessing when I say try going larger. Looks like a shadow bias issue with two surfaces that are very close together or intersecting. If the floor is a flat plane, try extruding it in to a volume. Doesn't have to be too thick. Helps with shadows on flat surfaces. Thanks for your reply. I'm sorry but I'm really new to 3D and Houdini. Where do I find the shadow bias? Also, what do you mean by "bad shadows in and around the stacked boxes"? I don't have an artist's eye so to me they look fine but please tell me so I can be careful next time. Is it a problem of density of the shadow or shape or else? Edited July 29, 2011 by kurisutofu Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted July 29, 2011 Share Posted July 29, 2011 If you look at the shadow under the cube closest to the camera on the lowest row, at the corner, you will see some light. I think the shadow should be a plain square. I believe your shadows are working correctly (in terms if bias) and accuracy. The area you describe includes the outer rim of the glass - it is not obvious, but it is there. The inner cube is casting a shadow, and the outer glass is. Perhaps you are *feeling* that it isn't correct because of this 95% transparent glass, and the shadow cast from the inner cube. The eye says something is mismatched..I personally did not catch that when first viewing your results. Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted July 29, 2011 Share Posted July 29, 2011 I believe your shadows are working correctly (in terms if bias) and accuracy. The area you describe includes the outer rim of the glass - it is not obvious, but it is there. The inner cube is casting a shadow, and the outer glass is. Perhaps you are *feeling* that it isn't correct because of this 95% transparent glass, and the shadow cast from the inner cube. The eye says something is mismatched..I personally did not catch that when first viewing your results. I recommend dialing up 'shadow intensity' as a test, by 25% and see if that corrects the issue. This setting will be in your light. You can also adjust your glass material to be less transparent - you could swap that shader out to something solid, as another test. Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted July 29, 2011 Share Posted July 29, 2011 I believe your shadows are working correctly (in terms if bias) and accuracy. The area you describe includes the outer rim of the glass - it is not obvious, but it is there. The inner cube is casting a shadow, and the outer glass is. Perhaps you are *feeling* that it isn't correct because of this 95% transparent glass, and the shadow cast from the inner cube. The eye says something is mismatched..I personally did not catch that when first viewing your results. You have more than 1 light - perhaps 2 or 3? Remember that 1 light can brighten the shadows cast from another light, essentially making them disappear (depending on position of course). Try testing with 1 light for that area in question, and cast shadows nearest the camera. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted July 30, 2011 Author Share Posted July 30, 2011 Thanks frankyoualot, I will try your advises. The thing is that I don't know why, but now I can't get the same result I had before ... I did some tests, reverted back to the original state (even used a backup file) and now the rendering is ugly, even after multiplying the samples by 3 ... I have to figure that out too Quote Link to comment Share on other sites More sharing options...
Peter Quint Posted July 30, 2011 Share Posted July 30, 2011 Thanks frankyoualot, I will try your advises. The thing is that I don't know why, but now I can't get the same result I had before ... I did some tests, reverted back to the original state (even used a backup file) and now the rendering is ugly, even after multiplying the samples by 3 ... I have to figure that out too You might also want to check if your glass material (if that is what you are using for the outer cubes) has fake caustics enabled, if it does try switching that off, or try altering the parameters. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted July 30, 2011 Author Share Posted July 30, 2011 I believe your shadows are working correctly (in terms if bias) and accuracy. The area you describe includes the outer rim of the glass - it is not obvious, but it is there. The inner cube is casting a shadow, and the outer glass is. Perhaps you are *feeling* that it isn't correct because of this 95% transparent glass, and the shadow cast from the inner cube. The eye says something is mismatched..I personally did not catch that when first viewing your results. I turned off one of the lights and I get the same result but with lighter shadows. And with those shadows, I could see why I had what I thought was bad shadows and I noticed you are right, they are not wrong! Maybe the light is bouncing from the glass and that creates the shapes we can see. The error came from me, not the scene ... Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted July 30, 2011 Author Share Posted July 30, 2011 You might also want to check if your glass material (if that is what you are using for the outer cubes) has fake caustics enabled, if it does try switching that off, or try altering the parameters. I tried and it looks a little better, thank you! Now I need to understand why I can't get the quality back to normal ... Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted August 2, 2011 Share Posted August 2, 2011 I turned off one of the lights and I get the same result but with lighter shadows. And with those shadows, I could see why I had what I thought was bad shadows and I noticed you are right, they are not wrong! Maybe the light is bouncing from the glass and that creates the shapes we can see. The error came from me, not the scene ... Yes - glass can be tricky, but worth the effort with it looks right..Definitely get your refraction values right - there are some starting point values (glass, water, etc.) online as well. As for quality settings - this is found in your output mantra node(s) - Pixel sampling @ 5 x 5 perhaps for testing.. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted August 3, 2011 Author Share Posted August 3, 2011 Yes - glass can be tricky, but worth the effort with it looks right..Definitely get your refraction values right - there are some starting point values (glass, water, etc.) online as well. As for quality settings - this is found in your output mantra node(s) - Pixel sampling @ 5 x 5 perhaps for testing.. For test I used pixel sampling 3x3. Then, the picture I displayed here was a 9x9. But now, I increased up to 18x18 (which I have tried before and I found was giving no visible improvement from 9x9) but I still get an ugly picture ... Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted August 3, 2011 Share Posted August 3, 2011 but I still get an ugly picture ... Can you define what is ugly about your picture? Would a different lighting scheme give you a different vibe, as in an area light? Try something image based (dome) and you may find what you're looking for..certainly you would gain some interesting reflections on your surfaces. Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted August 4, 2011 Author Share Posted August 4, 2011 Can you define what is ugly about your picture? Would a different lighting scheme give you a different vibe, as in an area light? Try something image based (dome) and you may find what you're looking for..certainly you would gain some interesting reflections on your surfaces. Let me show you. I haven't changed anything in the settings as far as I remember ... Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted August 4, 2011 Share Posted August 4, 2011 (edited) Let me show you. I haven't changed anything in the settings as far as I remember ... This render is different from the very first, yes? This one looks like you're using global illumination (env. light, skydome, image-based lighting). These are sampling artifacts. I can't recall at the moment, but look into increasing your quality and this will smooth out and disappear. Go slowly, as it will cost.. Or, these resemble photon artifacts.. What is the lighting setup for this render? Edited August 4, 2011 by frankyoualot Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted August 7, 2011 Author Share Posted August 7, 2011 This render is different from the very first, yes? This one looks like you're using global illumination (env. light, skydome, image-based lighting). These are sampling artifacts. I can't recall at the moment, but look into increasing your quality and this will smooth out and disappear. Go slowly, as it will cost.. Or, these resemble photon artifacts.. What is the lighting setup for this render? I tried to change the quality but nothing worked ... until I unchecked "prefilter photon" in the caustic light. Now it is back to normal, thank you! Quote Link to comment Share on other sites More sharing options...
frankyoualot Posted August 9, 2011 Share Posted August 9, 2011 Now it is back to normal, thank you! Excellent - can you post your results? Quote Link to comment Share on other sites More sharing options...
kurisutofu Posted August 9, 2011 Author Share Posted August 9, 2011 Excellent - can you post your results? It is the same as the first one I posted, where I thought I had a problem but then, as said later, I realized it was correct from the beginning Sorry for all the trouble ... Quote Link to comment Share on other sites More sharing options...
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