Weird noise on render, not on IPR

[3Dimensional]

I have an object very close to the camera which has some areas that I surfaced with a glossy material and a texture. I can't show the object, but think of it as groups of panels, some are white and some are almost black. The glossy material is set to its defaults, with specular at 51 on RGB.

The problem I have is that one of these groups of panels (which I think may be reflecting the sun, although not directly), has a very visible noise, which even at 1500 samples can still be seen when rendering. However, this noise is completely absent when using the IPR window. In the IPR, at worst there's a bit of noise right at the beginning, but at 100 samples it's completely gone.

Evidently there is something that the IPR does differently than the render to have that area without noise at only 100 samples, and the final render can't get rid of that noise even at 1500 samples. Any idea of what could be causing this and how to get rid of it?

Thanks

[juanjgon]

Are you rendering the two images (IPR and final render) at the same resolution? ... In theory all the settings are the same for the IPR and final rendering. Perhaps the image with more resolution could show more artifacts.

-Juanjo

[gordonrobb]

Do you have, in your settings, IPR set to be using a different gamma? Or, has the object been imported as an OBJ and may have some vertex normal applied (you can see it in the bottom of the normal surfacing window). Without seeing it, or a similar example, not sure if I can suggest anything, but perhaps others will.

[3Dimensional]

Are you rendering the two images (IPR and final render) at the same resolution? ... In theory all the settings are the same for the IPR and final rendering. Perhaps the image with more resolution could show more artifacts.

-Juanjo

Yes, both are 1280x720, and I have the settings to open the IPR at the camera's resolution.

[3Dimensional]

Do you have, in your settings, IPR set to be using a different gamma? Or, has the object been imported as an OBJ and may have some vertex normal applied (you can see it in the bottom of the normal surfacing window).

Can IPR be set to a different gamma? I don't see any setting to do that, where is that supposed to be? The gamma in the imager is set to 1.5 and response linear. I set it that way because 1.0 gives me a picture that has too much contrast and makes white objects overexposed, but 2.2 makes everything too flat.

As for vertex normal applied, there was none, but the drop down list would let me choose one called vert_normal. But if I had that selected, wouldn't it be the same for both IPR and final render?