help with vray render elements and vrimg/exr

[gfriedman]

i have been in able in the past to produce a vrimg and convert to exr to get separate render passes to work with in photoshop. i have proexr and am getting a few separate passes but the ones i want aren't turning out right.

 

for example, my z pass - which in the past has always produced various shades of grey depending on distance from the camera - is coming out black. I also was interested in material and object ids both of which are also black. I am getting other passes like GI and other ones I am not sure what to do with...i was mostly testing to see what is available....

 

any ideas why something as basic as z would come out totally black? is there a setting I'm missing?

[BrianKitts]

you checked the distance settings in the xdepth setup? If you're minimum value is super high or the same as your max value that would probably give you a black result.

[gfriedman]

i completely overlooked that setting. but now that I'm playing with it, I'm not getting good results...all zebra'd

 

and about material and object ids...do i need to give them these?

[gfriedman]

ok figured out the answer - next question - is there a way to automatically assign unique object ids, without having to go through them one by one and assigning each? I found a script for material ids...but not object ids

[BrianKitts]

you could do that with a script....

 

another option would be just to render the vraywirecolor element.... it will give you a render element colored by the objects wireframe color which makes it easy to select all the elements individually in post.

[alias_marks]

you could do that with a script....

 

another option would be just to render the vraywirecolor element.... it will give you a render element colored by the objects wireframe color which makes it easy to select all the elements individually in post.

 

+1 for this recommendation, very helpful and easier to set up in my opinion than obj id pass.

[Nic H]

do you get clean mattes with the wirecolour element? never used it.

[alias_marks]

I usually have to bump up the aa settings to something like 2/4 to get something good, but it's still pretty quick...

[WAcky]

I'm pretty sure the only pre-multiplied element that's useful for making passes is the multimatteelement. This will give 3 channels (R, G, B) which is easy to make a selection using the channels panel in PS) This way you dont need to render huge files with high AA settings to get a clean mask.

 

Either use a multimatteelement or get PSD man or use a renderpass script.

 

I can't image it would be anything more than a very simple 1 loop script to assign a unique object ID to any object. Hrm. This is tempting

 

Something like create a unique ID for selected items. Add enough multimatte elements to cover all the items and assign the correct numbers to the multimatte and save them out with a relevant name. hrmm.

[Nic H]

yeah would be a handy script

unique object ID from selection and corresponding multimattes.

 

sounds easy, unfortunately i cant do maxscript.

[WAcky]

Yeah I'm having a go at it now. Seems it's easy enough to add elements but I'm not sure if the parameters can be accessed. I'll get back to you.

[braddewald]

I use the VRayRenderID element... Is this better/worse than using the wire-color? Why?

[WAcky]

Because like all the others, except the MultiMatteElement, it's unpremultiplied and Photoshop doesn't play nice with unpremultiplied masks. And although the multimatteelement only renders out in 3 colours (rgb) it means you can use the channel selection functions in Photoshop to make a perfect anti-aliased selection.

 

The script I've been working on is almost done.

[WAcky]

Ok try this plugin.

 

It may or may not work but it basically creates multimatteelements for you.

It takes your selected objects, creates the necessary elements and warns you if any selected objects have existing ids.

 

Let me know how you go.

[gfriedman]

is psdman a plugin? know of any good resources for understanding premultiplied elements?...

[WAcky]

PSD manager is a plugin that outputs black and white masks and render elements to a .psd file for easy use. Click here.

The masks are premultiplied.

 

Photoshop works well with pre-multiplied masks but not with un-pre-multiplied masks. In order to work with un-pre-multiplied masks you need to be working in a program like nuke or digital fusion. Even then the workflow is tedious.