less reflection at higher resolution

[frame9]

Hi everybody!

I am having a strange issue which I just don't manage to fix.

I have a wet road with some reflections. Diffuse, Refl gloss and Bump
Everything seems fine in IR and to a certain resolution (1500px for example) but the higher I go on the resolution the less reflective the material gets??
There is an image (region) of an IR 853px , 1500px and 2500px attached.
Does anyone have a clue what the problem might be?
I started the scene in Corona 2 and then merged it into a new file after installing corona 3.
I don't remember having this issues in corona 2 but I am not sure.
I changed Displacement screen size 3,0 px to world size 1cm (both was default) which made things a bit better but still not close to IR and a low resolution.

Thanks for your help,
Tobias

[frame9]

Here is another more simple example with only the crosswalk. 800px and 2500px
It's also Diffuse, Refl gloss and a bump map
The light is a CoronaLightMtl

[frame9]

Ok. It seems the bump map is the problem.
If I delete the bump it looks the same.

But how do I fix this issue?

[frame9]

hm... does nobody have an idea what the issue might be? :/
or is my question just to stupid to answer?

[mferster]

It's the blur filtering on your bump map. Try lowering your blur filtering to 0.2 or something like that.

[FrostKiwi]

That is the unfortunate state of 3dsMax's current texture handling.
It's a well known issue with no correct answer, except going by eye.

Thread with similar issue:

But the worst part is, that blurring is highly dependant on rendering resolution and camera position, so there's no single "true" value and you constantly need to fiddle with that. Such thing should be automatic.

[frame9]

thanks for the reply!

hmm! ok. that sucks
this means that the IR and low res previews are completely unreliable...
i need to check if this problem also occurred in corona 2, because i don't remember having this issues before... but i am probably wrong.   

[mferster]

lowering your bitmap filtering mitigates this. It's always been present.

[frame9]

ok. thank you.
I will try it.

[frame9]

I just tested the scene with corona 2 and it looks much better to me and it's also a lot closer to IR and low res!
It just gets more detail when rendered in a higher resolution.
The bump (and therefore the reflection) also changes with the angle of the view or distance (not sure which one).

@mferster
best solution is probably lowering your bitmap filtering from the get go, as you said.
I need to check if it's also good for smooth bumps.

Is there a reason why the behavior of the bump changed in corona 3?

[TomG]

There is the preservation of detail in maps at grazing angles ("sharper textures at grazing angles") which may be playing a part.

[frame9]

thanks for the reply!

is there a way to turn it off?
i think it makes it really hard to anticipate the outcome of an image in a higher res and it interferes too much with the reflections.
lowering the bitmap filtering might be a solution but it makes things just a bit more complicated.

i dont't want to sound negative just keep things simple ;)

[TomG]

No way to turn it off at the moment, sorry - in general, everything should always look better with it, it may just not look the same as it did in Corona 2.

[frame9]

ok. thank you

i'll have to get used to it then.