View Full Version : VPR_vs_Render

05-05-2011, 03:06 PM
Hi guys.
I am working on texturing and shading a model, can someone help me understand why the vpr render is so different to the f9 render?
This only happens when I use the node shader material simple skin, I tweak, getting the look I want which is updating in vpr just great, but then my render is nothing like it.


05-05-2011, 04:10 PM
Because it's a previewer, not a final renderer?

05-05-2011, 04:16 PM
Simple skin is not compatible with VPR, and neither are most of the SSS shader nodes, or anything which calls a pre-compute function before the renderer. This is no different to Fprime, which also can't use any shader which calls a pre-pass before the render.

NT are aware of this and are working on improved shaders and improvements to the VPR system.

NB: You should report this in the HC area as discussions about specific HC issues aren't supposed to be made public. Suffice it to say a lot of the new functions in LW 10.x are still in beta.

05-05-2011, 04:24 PM
Thanks Tobian.

05-05-2011, 04:48 PM
To me this looks more like ColorSpace settings difference, Did you save your Render as Linear or sRGB ? VPR looks like sRGB and render like Linear.


05-05-2011, 04:50 PM
You should check out a new feature in LW 10.+ you will really like, if you haven't already download the latest build, and watched the preview vid, you should!

05-05-2011, 07:33 PM
Thanks Lewis, the colour space settings are the same, both are linear.
It just seems to be any material node thats different in vpr and render, if I turn off the material node both vpr and render are identical.

05-05-2011, 07:54 PM
Yep that sounds like what I thought. The shader is made up of a diffuse+reflection+spec+sss element, and the difference is all of that - the sss part, which VPR can't do. Hopefully the latest news should please you! :D

05-05-2011, 10:10 PM
Another reason that renders in VPR might look differently is beause VPR uses a draft mode by default which renders faster but doesn't do as full a job as normal. You can check it off in the VPR options found in the top right hand corner of the window.

05-05-2011, 10:50 PM
VPR is great but it is only a preview, if you have a stack of polys it's a bit painful even with a pair of W5580 CPUs. So a small render with low AA is almost as quick.

Having said that for a bit of fun with monitor real estate!.....

05-06-2011, 01:21 AM
Have I been mistaken the VPR promotion wrong along the line?
As I percieved it..I thought it should and could render almost anything, with emphasis of not being a previewer like other software or fprime, but what you see is a low res iteration process
that is as the final renderer, except post processing to match that as of the final render?

Ivé recently been testing dielectric materials, only to found out that there
seem to bee quite big differences in how glass is rendered, that is a bit unfortunate since glass is a such delicate material to tweak, and not matching the final renderer, makes it less useful to use the vpr at all for glass tweaking.

I love the VPR for many other stuff thou, but I was just a little dissapointed that glass dielectric doesn´t seem to render properly to match that of final render.

The conductor material seems okay thou, but who knows if it suddenly appears completly different render in the final render once you tweaked it in vpr?


05-06-2011, 07:39 AM
Guys. I think this is pushing the nature of the NDA somewhat. Perhaps a mod can move this thread into the HC area?

05-06-2011, 07:53 AM
Guys. I think this is pushing the nature of the NDA somewhat. Perhaps a mod can move this thread into the HC area?

How ? Isn't Trevor using LW10 released in DEC 2010 and Simpleskin node+VPR? What's under NDA there in LW which is released 5 months ago ?

I don't see him showing 10.x layout or saying which version is this?

05-06-2011, 08:32 AM
Yes but like I said the work on VPR is ongoing and there are certain *things* In LW 10.1 which aren't properly public yet, which will help him out. I don't know how to make it more obvious than saying it Lewis, which I can't, obviously.

Elmar Moelzer
05-06-2011, 09:02 AM
I think that VPR does a lot and it does it very well. Dont forget that this is only the first release.
There are some smaller issues, most of them are due to the legacy of some features, which were never designed with something like VPR in mind (some nodes that use preprocessing come to my mind here).
I guess that NT will improve on these issues in coming releases and that more things will work with VPR in the future.
This is only the very first version after all.
IMHO, it actually does more than I would expect from it.

05-06-2011, 09:08 AM
Well this is the thing. It is very early software, and it will be constantly refined during the LW 10 and on series, as both Renderer and VPR gain greater parity, which is where we start to get into features which are under revision, and still not released to the public sphere. There's a specific feature of the latest build of VPR which addresses this very point, so you should go get it! :D

Elmar Moelzer
05-06-2011, 09:25 AM
Tobian, please try to be a bit more vague, we are all under NDA here, after all ;)
There I am, trying to be as subtle as possible and then you come along, gggg
Well yeah, what Tobian said.

05-06-2011, 10:46 AM
Thanks for your input.
I have found the thing thats making the vpr different from the render. I have a gradient set to bump parameter driving the luminosity channel.
If I change the values here, vpr reacts but the f9 render does not.
So it seems the material node is bypassing this channel in the final render.

My next question is how do I plug in a luminosity gradient so that the render does react? The vpr render is close to what I want, I just cant seem to get the same results in the render.

05-06-2011, 11:18 AM
All of the 'materials' completely disable all classic surface properties (values or the texture layers) much as any node shaders disable/overwrite classic surface settings also. Since your render in VPR is using the classic surface settings, that means all you are getting is classic settings, and nothing from the node shader (as we said, VPR doesn't support all materials).

How to customise your own material, with blended luminosity.. hmm, that's going to be tough, but the simple answer is to not use the skin shader at all (which is more or less what you have now :D). The problem you have is most 'materials' are much more simplistic in terms of the inputs they accept because they are specifically designed for their purpose: dielectric makes glass, conductor makes metal, and the skin shaders make skin simulations. Or more importantly, for you, they stop you from adding things which have no reason to be there! To mix in 'imaginary' material properties, which they don't support you will have to use the material mixer and use a classic surface editor, and some sort of incidence angle mask. Like I said.. tricky!

05-06-2011, 11:46 AM
Since your render in VPR is using the classic surface settings, that means all you are getting is classic settings, and nothing from the node shader (as we said, VPR doesn't support all materials).

Thanks Tobian.
Heres where im a little foggy, because the simple skin shader is working in vpr, I cranked up the settings to extreme in this vpr render, the sss is clearly having an effect. Along with this the bump channel is active in the classic settings which also seems to be playing nice.


I think the best way to achieve the results I am after would be to render in multiple passes and comp in post. That way I can get all the elements I need.

05-06-2011, 03:24 PM
I can't deny it's doing something, but ultimately it's not looking the same as renderer, so nice as it is you have to go with what renderer is doing, not VPR. Passes would also be a way to do what you want to achieve too. Whatever works! :)