Only glas in png file

[Jorgensen_cg]

Hi

I often use Photoshop to adjust reflection in windows. Is there any way to only save glassmaterials to a png file ? I have played around with material ID, render Id, reflection but haven't found a method yet.

Can anyone help ?

Thanks

[jrharvey]

Re: Only glas in png file

Check the affect "alpha button" on the material settings. Is that what your looking for?

[Jorgensen_cg]

Re: Only glas in png file

unfortunately not. I think, if the alpha has to work, the glass has to be placed where you can see through the building - or am I wrong ?

Thanks

[jrharvey]

Re: Only glas in png file

ya true

[dalomar_cg]

Re: Only glas in png file

I often use Photoshop to adjust reflection in windows. Is there any way to only save glassmaterials to a png file ? I have played around with material ID, render Id, reflection but haven't found a method yet.

In order to really do the kind of modification that you're looking for, you'd have to assemble a full composite. Basically, a final render is a series of different pieces that come together to create what you see. If you take each of these pieces individually and "assemble" what would be the final render yourself, then you can go ahead an make the kind of modifications that you're looking for. I'd have to dig through a bunch of my notes to get you through the steps of putting together a full composite. Its not the hardest thing in the world, but it does take a good amount of setup. If that's something you're interested in, then let me know.

[Jorgensen_cg]

Re: Only glas in png file

Hi Dalomar

I think you lost me there ???

[dalomar_cg]

Re: Only glas in png file

Okay, the resulting image is a combination of a lot of different pieces which V-Ray calculates...diffuse, GI, Lighting, reflection, refraction, etc.... If we want to change one of those sections individually its going to be very hard to do so when working with the final result. But if we have each of those pieces composited together, then it is much easier to make a modification on just the diffuse color or just the reflections in your case because each of those pieces are their own image. I guess that's as simple as I can explain it....once you see it visually I think you'll get it much easier.

[Jackson_cg]

Re: Only glas in png file

If I understand correctly, you're just looking for a simple way to create a mask which you can use in Photoshop to select all areas which have the glass material, right?


A trick I used once (when we were happy with the final night render which had taken a few hours, but just needed to adjust brightness of interiors in PS without re-rendering) was simply to save a copy of the skp file, make the glass material 100% opaque and bright red (or another colour which doesn't occur elsewhere in the render), reduce your visopt quality really really low (as you're only going to use the render for masking) and export the "Diffuse" VFB channel. Overlay the diffuse channel render as a new layer over your previous render in PS and using colour range (low setting- probably 50 or less) choose the colour that your glass has rendered and make a mask from it. Set the diffuse channel layer to invisible, select the orginal render layer and you can can work away on it while only affecting the glass.

[dalomar_cg]

Re: Only glas in png file

I can't remember whether its the MatID or ObjectID channel, but that will essentially get you a mask that you can use to select the area in question in PS. HOWEVER, there's a right way and a wrong way to do this. Your suggestion, although useful when in a pinch, is essentially working with modifying the final result. If you're looking for a way to just tweek the reflections (not the refractions behind it, not the potential color of the glass or any other object), then the only way to be able to access those effectively is by putting together some sort of composite.

Again, putting together these composites aren't incredibly complex, just slightly time consuming the first time you try it, and the flexibility that they offer is astonishing. There are several very simple comps that you can put together, but the "minimal" full comp is a formula as follows (all variables are channel names).

Lighting+GI+Self Illumination+Reflection+Refraction

If you want to get more complex and have more flexibility (ie change diffuse colors and things like that), then you can put together a slightly more complex comp that splits out diffuse info from the lighting info. The only thing I'll note about this is that GI will still have some color information in it, since the light itself is colored by the materials. Just note that if you're making material changes.

(Raw Lighting*Diffuse)+(Raw GI*Diffuse)+Self Illum+ Reflection + Refraction

The last major thing that you can add in regards to more flexibilty/complexity is to split out the reflections an refractions. This way you can adjust them while maintaining their falloff.

Lighting+GI+Self Illum+ (Raw Reflection*Reflection Filter)+(Raw Refraction*Refraction Filter)

Notice how for that last one I put the (Raw Lighting*Diffuse) back to just Lighting. Feel free to "mix and match" how those initial 5 channels are broken down (4 really...Self Illum can't be broken down).

In regards to what you'll need in photoshop, you can perform these mathematical operations through layer blending modes. For the addition operations, you will need to use the Linear Dodge mode. For the multiply operations, you guessed it, you'll need to use the Multiply mode. Last thing is that you may need to group any of the layers that are multiplied together. I can't remember whether that's required or not since its been a while since I put a full comp together (sorry, my clients are you guys )

http://www.spot3d.com/vray/help/150R...erelements.htm