Mental Ray bitmap texture filtering question

#1

Hi,

I’ve noticed a couple of times when I’ve been rendering with mental ray, and had textures that are high contrast/fine detail, such as logos or type, that I often get pixels disappearing.

This doesn’t happen nearly as much in the scanline renderer, and I was wondering if there are any settings within mr that would help.

I’ve tried bumping up the samples per pixel, and it helps to some extent at the expense of render time, (and the geometry aliasing is not really the problem), is there something specific to the bitmap filtering in mental ray that might help?

Thanks,

Steve

#2

Have you tried tweaking the blur value in the bitmap coordinates rollout? Are the details being “blurred” (filtered) out, or dropped, like fine geometry detail sometimes is?

#3

Hi,

dropped rather than filtered.

Unfortunately if I tweak the blur, the client tends to complain that the graphics are too blurry, so I end up rendering them separately in scanline and comping.

Thanks,

Steve

#4

Hmmm… what value are you using for the blur???

In my experience, it’s been a balancing act. Getting the right balance between filtering and sampling, so the renderer doesn’t loose small details in the maps, yet they remain crisp…

It can be especially difficult in close views with the camera being parallel to the surface.

Mental ray does support “high quality elliptical filtering”, but I don’t think max’s integration supports it.

What version of max are you on?

Have you tried the mental ray map manager in the render dialog - processing tab? It uses alternate filtering algorithms according to the max help file…

I believe Zap’s arch Environment Blur shader takes advantage of elliptical filtering.

Max’s mental ray integration could use a custom texture loader (better than the cheesy “mib” ones that you can unhide from the base.mi file).

#5

Hi,

thanks for your reply,

I’ll have to get back to you - I’ve got to get a few renders out today.

I’m using Max 2009 BTW, but it’s something I’ve noticed for a while.

Thanks,

Steve

#6

Did you try reducing the blur to .01 ? I often must do this to keep from losing the detail in my maps, especially at grazing angles.

Regards,
Mike

#7

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.