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Maniphest T45586

Render preview in viewport different with regular render
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Description

System Information
windows 7 with sp1

Blender Version
Broken: 2.75a c27589e
Worked: (optional)

Short description of error


With small size light, the transition between light and shadow have clear sawtooth in preview render(left), but smooth in regular render(right)
Exact steps for others to reproduce the error
As shown above, just one sphere with smooth shade, and the light keep default, just increase the light strength, notice the light size with 0.1, and you can see, the transition between light and shadow have clear sawtooth , though you can solve it by increase the light size, but the shadow will become soft. as you know , the regular render can't find this, just in viewport render. and I guess this problem created by truth normal, and not the smooth normal, though it's not affect the final result, but not good for preview, maybe this one bug, or maybe I don't know the option where to set this. sorry for my stupid :D

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Event Timeline

Leroy (Leroy) created this task.Jul 28 2015, 2:38 AM
Leroy (Leroy) raised the priority of this task from to 90.
Leroy (Leroy) updated the task description. (Show Details)
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Sebastian Koenig (sebastian_k) added a subscriber: Sebastian Koenig (sebastian_k).Jul 28 2015, 8:13 AM

Are you sure you don't have a Subsurf Modifier on that sphere with a different detail setting for viewport and render?
Because with just a default sphere I cannot reproduce it.
Maybe you can attach your blend file?

Sergey Sharybin (sergey) changed the task status from Unknown Status to Unknown Status.Jul 28 2015, 10:28 AM
Sergey Sharybin (sergey) claimed this task.
Sergey Sharybin (sergey) added a subscriber: Sergey Sharybin (sergey).

You've got difference subdivisions levels for render and viewport in your model and viewport levels are not enough to produce nice smooth interpolation of normals. It is known behavior, will be eventually improved but for now is not considered a bug.

Leroy (Leroy) added a comment.Jul 28 2015, 1:06 PM
In T45586#324327, @Sebastian Koenig (sebastian_k) wrote:

Are you sure you don't have a Subsurf Modifier on that sphere with a different detail setting for viewport and render?
Because with just a default sphere I cannot reproduce it.
Maybe you can attach your blend file?

In T45586#324337, @Sergey Sharybin (sergey) wrote:

You've got difference subdivisions levels for render and viewport in your model and viewport levels are not enough to produce nice smooth interpolation of normals. It is known behavior, will be eventually improved but for now is not considered a bug.

sphere.blend516 KBDownload

this is .blend file ,maybe my english not good ,you can't see it clear, I'm meaning no subdivision modifier, preview and render all same samples, this produced affected by the light size and the face in mesh( e.g. add much more sudvision will much more smooth ), more small light , more hard shadow， more sawtooth... and I do it again, and the sawtooth have in render, not affected by the smooth shade:(

Sebastian Koenig (sebastian_k) added a comment.Jul 28 2015, 2:30 PM

Weird. For me this renders identical. Can't see any errors.

Sergey Sharybin (sergey) added a comment.Jul 28 2015, 2:41 PM

Same happens here, in both viewport and final reneder you can see that there's shading artifacts. This happens exactly because of too much different normals on the face vertices which is causing artifacts after interpolation the normals.

Just add subsurf modifier to make normals closer to "ideal" ones.

Leroy (Leroy) added a comment.Jul 28 2015, 2:50 PM
In T45586#324445, @Sebastian Koenig (sebastian_k) wrote:

Weird. For me this renders identical. Can't see any errors.


the transition area between light and shadow at the sphere have clear sawtooth,,,not smooth ,the normal is smooth shade,,but it's have sawtooth, it's flat shade at transition, only flat at the transition area, I'm wrong at first , sorry for that, I am focus at the sawtooth, my friend tell me the Octane render have same error before, but fix now, and same problem at cycles, through you can add subdivision on mesh ,or set the light much more big, it's meaning the shadow much more soft.

Leroy (Leroy) added a comment.Jul 28 2015, 2:58 PM

if mode simple, can add subdivision, but not an practical method for complex mode, it's should have optimization on cylces, I guess have much more good method :(