How to extract VrayMtlID and VrayObjectID from a vrimg file ?

[edgy_k]

Hello,

I usually make my rendering directly to vrimg and the nextract the channels to exr because I make large renderings (4000+ pixels) wich always crash 3ds max if I enable the vfb. I'm ok with that workflow.

But now, I need to also extract some other render elements wich are object IDs and Material IDs. To my surprise, I discovered that it is impossible to extract them with vrimg2exr tool.

Is this a known limitation of vray or am I missing something ??

Thanks

[martincg]

did you checked if that elements are enabled in render settings before rendering?

[Crazy Homeless Guy]

i don't know about extracting them from the vrimg file, but an alternate way would be to write them out to seperate files using the "split render channel" dialog, also located under the vray frame buffer rollout.

[anvaraziz]

nop,, as far as i know u cant do that .. if u find any way pls post it in this thread itself.it ll be very helpfull..

 

Thanks...

[edgy_k]

i don't know about extracting them from the vrimg file, but an alternate way would be to write them out to seperate files using the "split render channel" dialog, also located under the vray frame buffer rollout.

 

Yes, but as I said, because my renders are so large I have to disable "render to memory frame Buffer" wich automatically deactivates the option to split the channels That's why my only option would be to extract those channels directly from the vrimg file.

[Christopher Nichols]

Using the command line do this:

 

vrimg2exr image.vrimg image.exr -channel VRayMtlID

 

the vrimg file hold all the data, and actually the exr is also a multi-layer exr but you need a program that can read the multi layers like Nuke.

[Ricardo Eloy]

Didn't know that one, Chris... Does it automatically hold the info for all channels or we still need to activate the render elements?

[edgy_k]

Using the command line do this:

 

vrimg2exr image.vrimg image.exr -channel VRayMtlID

 

the vrimg file hold all the data, and actually the exr is also a multi-layer exr but you need a program that can read the multi layers like Nuke.

 

Wow ! Nuke ! That's heavy artillery for me. As I exclusively work on stills, I only use photoshop, wich alas doesn't handle layers in exrs afaik.

Maybe the new CS3 does that ?

[Christopher Nichols]

yeah... you don't need nuke... but if you have nuke, you would not need to use the -channel option, since you simply expose those channels. Otherwise... try the -channel option... that will work for you.

[edgy_k]

Well, there's a little problem :

 

- The MtlID channel is present in my vrimg file. I can verify that when running vrimg2exr -info

- But if I try to extract it I get this message : "Specified channel name "VRayMtlID" not found or channel is not a RGB channel in file..."

- As the channel is present, the error must be that is "not a RGB channel". And indeed it is reported as "type: integer" while all other channels are of type: RGB color

 

So maybe the solution would be to force vray to output this channel as RGB... but is it possible ?

[ishpalsingh]

even i don't how to extract vraymatid from vray elements it always comes out black, is there anything i am doing wrong?