rendered objects are different from different distance?

[kema]

hello there

this is a very quick test scene, but i noticed the outcome is a lot different once i start to zoom in closer to the object.. it becomes a lot brighter for example

simple hdri as environment and a corona light, a very glossy material with a fingerprint assigned to the reflection
but i also noticed this when i use layered mtl for example.. details are going away once i move camera closer to the object... and while the IR seems ok, final render is different (brighter for example, like the attachent)

what is this? am i expecting something wrong or this is how it should work? please light me up :)
thanks

[romullus]

Hi,
Can you tell us how did you zoom in? By moving camera closer to the object, or by changing field of view? If former, then changes in material appearance might be expected, because of changing viewing angles between the camera, the surface and a light source. On the other hand, the difference might be because of texture filtering (don't confuse with image filtering). When the object is farther from the camera (smaller in rendered image), its texture is filtered accordingly to texture filterring settings in bitmap loader. Bump map is notoriously sensitive to texture filtering, but other channels might be affected as well. You can try to play with filtering blurring and different interpolation method, maybe try to change to Corona bitmap and choose bicubic smoother method. Also it's worth to mention that filtering depends on final image's resolution - the bigger your rendered image will be, the less adverse effect filtering will have.

P.S. you should map reflection glossiness, not reflection itself, as that would be more physically correct and might even lessen the issue with filtering.

[maru]

I may be completely wrong, but it looks like in those two pictures the reflections in the teapot are completely different. The 1st one shows a lot of black "background" and the 2nd one is zoomed in on a reflection of some bright shape like a light or a wall.

[kema]

hi

thanks

i was using zoom (alt+ z) in perspective view and also used corona camera placed close to the object, same result always

i used mapped specular yes, and this happened always when i used that method.. if i didnt use mapped spec, doesnt matter how much i zoomed in, it was good

it was not even corona bitmap, just dragged the image map to material editor, override its gamma to 1.0, thats it, i didnt even think about filtering, what is that texture filtering, how can i control it?

looks like i have to live with this, and skip mapped spec where i can, at least on non-organic objects

[TomG]

What seems like a good next step would be if you can share this scene with us - you can use the private uploader if needed, as it would be good to have the background HDRI and all the maps too (which you may not be able to share publicly).

[Vlad_the_rant]

@kema Why are you changing the bitmap's gamma to 1.0 exactly? Corona is not so good with linear workflow (1.0) so it should generally be avoided whenever possible. The idea behind Corona is to give you an image you may not even need to edit in post, right out of the VFB and it all works in gamma 2.2 by default.

[kema]

i just change the texture import gamma with this in mind:

"When loading ordinary bitmaps (for example into "diffuse" slot), you should always use "Automatic" gamma setting. When loading bump, displacement, or normal maps, it is correct to use gamma override of 1.0. You may also want to use gamma 1.0 for other grayscale textures, such as refraction level, reflectivity, opacity, etc., but this can be dependent on the kind of result you are seeking."

https://coronarenderer.freshdesk.com/support/solutions/articles/5000515647-how-to-configure-gamma-


i will make the scene again and share it, that private uploader is here on the forum? how to do it? thanks

[TomG]

Private uploader details are in the "how to report..." links in my signature - that means they are easily found whenever I reply to any post :)

[romullus]

i just change the texture import gamma with this in mind:

"When loading ordinary bitmaps (for example into "diffuse" slot), you should always use "Automatic" gamma setting. When loading bump, displacement, or normal maps, it is correct to use gamma override of 1.0. You may also want to use gamma 1.0 for other grayscale textures, such as refraction level, reflectivity, opacity, etc., but this can be dependent on the kind of result you are seeking."

https://coronarenderer.freshdesk.com/support/solutions/articles/5000515647-how-to-configure-gamma-

I think Papuca3D simply confused your mentioned input gamma with global gamma settings. Your approach here is correct.