Hi,
Create a Torus and a light, Render…
Why get hard result even with smooth normal ?
Full Version: Hard render result with smooth normal
that's quite common artifact when having low poly geo with interpolated normal and sending rays (shadow, reflection, etc), since they still intersect the low poly geo
in your case it's mostly raytrace shadows, to get rid of that you better have higher res geo or render as subdivision surface
in your case it's mostly raytrace shadows, to get rid of that you better have higher res geo or render as subdivision surface
hi tamte,
Low poly cause the artifact is make sense.
But when I use 3dmax and SI mental ray , I never met this problem even lower poly.
Low poly cause the artifact is make sense.
But when I use 3dmax and SI mental ray , I never met this problem even lower poly.
try checking ‘Backface Removal’ at the obj level/Render/Geometry tab
wow ! Just this reason. MartybNz, thanks very much!
I find a new problem when i check Backface Removal.
ah - yes - I had a closer look and its the shadows that is causing the blackness.
Try increasing the Ray bias to 0.3 in Mantra / Properties / Shading to push the shadow away. Turning off shadows in the light will also solve it.
Edit - just tested the torus in AtomKraft(3delight) and the same results - ray traced bias ‘fixes’ the shadow. Edit2: Nuke's Scanline also needs the fix
Try increasing the Ray bias to 0.3 in Mantra / Properties / Shading to push the shadow away. Turning off shadows in the light will also solve it.
Edit - just tested the torus in AtomKraft(3delight) and the same results - ray traced bias ‘fixes’ the shadow. Edit2: Nuke's Scanline also needs the fix
I find the shadow will detach from cast object when I increase Raytracing Bias.
How'd did you go Jerry7? A great way to learn is to keep testing.
A solution is to stop self-shading and it's buried in the shader. You can dig down to ‘Pbrlighting’ vop and turn off shadows.
note: You'll have to ‘Allow editing of contents’ to modify the shader
A solution is to stop self-shading and it's buried in the shader. You can dig down to ‘Pbrlighting’ vop and turn off shadows.
note: You'll have to ‘Allow editing of contents’ to modify the shader
hi, MartybNz
From your sample scene, I know the reason for hard shading is Self Shadow with Double side.
If I use Backface Removal ,the shadow detached from object's intersection that can't be accepted for product.
If I don't Backface Removal , the shadow border not smooth.
If I close self shadow as you sample scene, the final result is not be accepted for some scene that need selfshadow.
So ,I have no idea about it now!
PS: even I increase segment , shadow border is still jagged.
From your sample scene, I know the reason for hard shading is Self Shadow with Double side.
If I use Backface Removal ,the shadow detached from object's intersection that can't be accepted for product.
If I don't Backface Removal , the shadow border not smooth.
If I close self shadow as you sample scene, the final result is not be accepted for some scene that need selfshadow.
So ,I have no idea about it now!
PS: even I increase segment , shadow border is still jagged.
Running some simple tests in MR in Maya shows the same shadowing artefacts.
What MR settings do you use to avoid it in Max and SI? Thanks!
What MR settings do you use to avoid it in Max and SI? Thanks!
I use default MR setting in SI. Only a infinite(distant) light with torus.
Can you please fbx export that scene and upload; it has weird shading and there is also a shadow artefact on the torus. i.e. detached from the shading
These points you mentioned is cause by low poly segment, not Hard Aritfact. when you increase segment ,these artifacts are disappeared.
it's fbx. Nothing instresting ,just a low poly and a light.
Those shading and shadow artefacts are indicative the way the model was shaded and rendered.
Can you upload a render of the shadow pass and render - lets see how the shadows are constructed in MR. Thanks!
Can you upload a render of the shadow pass and render - lets see how the shadows are constructed in MR. Thanks!
it's shadow pass.
Look at your normals. The Fbx imported scene has different normals to a torus created in Houdini.
You can then turn on Backface culling, drop the bias to a smaller number to remove the shadow gap. You can also add thickness, another grid, to the ground to totally remove the air-gap.
You can then turn on Backface culling, drop the bias to a smaller number to remove the shadow gap. You can also add thickness, another grid, to the ground to totally remove the air-gap.
oh.. sorry, but i can't get your result with the attachment scene. Where am i wrong?
Good times reading up on this very cool area of shadowing.
It boils down to when a polygon/primitive is orthogonal to the light and can be declared a backface, i.e. the normal facing away from the light. The option to backface cull in Houdini appears to apply to lights as well as the camera. A combination of this and bias is the favoured solution to getting rid of it.
In gaming it's known as Projective Aliasing.
http://msdn.microsoft.com/en-us/library/windows/desktop/ee416324(v=vs.85).aspx [msdn.microsoft.com]
Blender's Cycles has it and Nuke's Scanline Percentage Closer Filtering shadows can use a bias slope control that will ‘hide’ this visual artefact more gracefully than a pure bias control. It appears to be simply luck that SI/Max MR don't show the issues, though, can't actually test it here see what is really going on under different conditions. The MR defaults in Maya 2014 certainly show issues.
Ah, and floating shadows is called ‘Peter Panning’
It boils down to when a polygon/primitive is orthogonal to the light and can be declared a backface, i.e. the normal facing away from the light. The option to backface cull in Houdini appears to apply to lights as well as the camera. A combination of this and bias is the favoured solution to getting rid of it.
In gaming it's known as Projective Aliasing.
http://msdn.microsoft.com/en-us/library/windows/desktop/ee416324(v=vs.85).aspx [msdn.microsoft.com]
Blender's Cycles has it and Nuke's Scanline Percentage Closer Filtering shadows can use a bias slope control that will ‘hide’ this visual artefact more gracefully than a pure bias control. It appears to be simply luck that SI/Max MR don't show the issues, though, can't actually test it here see what is really going on under different conditions. The MR defaults in Maya 2014 certainly show issues.
Ah, and floating shadows is called ‘Peter Panning’