VFB clearing when re-rendering

[Pixelcon]

I've had this problem for ages and I have no idea whether it's a bug or me missing a setting.

When I render a region over a previous render it clears my VFB. I have the 'previous render' setting set to 'unchanged'.
I had thought there was a particular render element that when used caused this to happen but I have just cleared my elements and it's still happening.
Im using max 2014, win 7 64 with vray 3.00.03.

I need to spot render a bunch of changes in my render and can't deal with the idea of having to deal with 20 separate renders and their masks...

Cheers,
James

[AlexP]

I've had this problem for ages and I have no idea whether it's a bug or me missing a setting.

When I render a region over a previous render it clears my VFB. I have the 'previous render' setting set to 'unchanged'.
I had thought there was a particular render element that when used caused this to happen but I have just cleared my elements and it's still happening.
Im using max 2014, win 7 64 with vray 3.00.03.

I need to spot render a bunch of changes in my render and can't deal with the idea of having to deal with 20 separate renders and their masks...

Cheers,
James

I also have this quite often, I generally notice it starts happening once Ive changed render element settings or resolution etc. Very annoying

[matanov]

I also have this quite often, I generally notice it starts happening once Ive changed render element settings or resolution etc. Very annoying

If these are the only situations (change resolution/render elements) that makes VFB reset, it's not a bug. If you have other conditions when this problem occurs - please report. Sorry I can't give you more technical explanation why, I'm sure someone will

[AlexP]

It definitely happens inexplicably at times also.
oops resolution is an obvious one, getting mixed up. The exposure window and info window disappear sometimes when I change resolution...

[Pixelcon]

I didn't change anything aside from some materials. I tried to re-render and then it cleared the vfb although I'm not sure if has been doing it throughout the life of the scene. I'll see if I can strip the scene and get it to repeat.

edit: I have a sneaking suspicion it could be forest pack but i'll do some further testing...

[Pixelcon]

ok so I think I've worked it out. It seems to be related to how long the name of a render element is. If a render element is added (problem doesn't arise when renaming the alpha channel) the problem won't arise. If you add a render element and make the name of the render element 64 characters or longer this problem appears. It's repeatable for me.

I know 64 characters sounds long but I use a script which automagically creates my multimattes and this always generates element names longer than 64 characters.

Thoughts?

On a side note: it seems even so much as renaming an element will case the VFB to clear. How annoying :/

[svetlozar.draganov]

Thank you very much for your feedback.
We'll add this issue into our system and will update you when we have some news about it.