How to add specularity map in Vray materials option ?

thegunslinger · 8 Nov 2011, 15:45

If it can help those who asked the same question that I did YES i'll be glade to put all what I've learned up to now ..

I suppose that turning off the sun mean disable the physical camera (or the exposure), euh yes, because I've used an hdri file but I didn't enable the defaults lights under the global switches menu and neither adjust it in the reflect color under environment menu. it was just a little test to see how the specular map will work with artificial light sources .
Yes andy, i totally agree with , The GI color will only affect the brithness of the model's textures ( increase the amount of white when increasing the value of the GI color)
Here is an exemple below.

thegunslinger · 8 Nov 2011, 17:00

We can also sorte out the mtexture when playing with the value of BG color and the Sm .
HERE is same difference when using the speculartiy map ( euh I used a diffuse map in this case i'll try it next time with another material with its own sm )

The BG color affect the brightness of the refelction and the image of back ground of course.
Sm will affect the type of the reflection .
You can see same difference between the images below..
I also used an hdri file ..

![BG color 10 " It gives a good wet aspect euh.."](/uploads/imported_attachments/gc3X_hhh.png "BG color 10 " It gives a good wet aspect euh.."")

john2 · 10 Sept 2012, 09:35

@thegunslinger said:

I had worked for hours to get the aspect that i've seen in the demo in this site : http://www.arroway-textures.com/catalog but still don't get it .
Can we get this result with Vray for sketchup ??

I don't think that the reflection filter is used for the specularity; this is what it's said about it in Vray for sketchup " manual "
Reflection Filter :
The filter color is used to apply color to reflections. You can see that by changing the filter color
on each of the renderings below the color of the reflections change. The magnitude of this effect
will change based on the strength of the reflections themselves. In the case of materials which are
very reflective, filer color may be an effective way to change the object’s appearance.

About the reflection glossiness :
You don't always get clear reflection from reflective material. Objects like matte finish metal, wood and some plastic materials do not reflect the lightsource clearly due to its uneven surfaces. This is because the
uneven surfaces create many reflecting angles for light to bounce around. So the highlight is not as sharp if compare to reflection from smoother surfaces. The best way to create this kind of rendering quality is playing around the setting of both Highlight Glossiness and Reflection
Glossiness

The specularity map is used to reflect the light form bright object "lightsource" and sun and let only some part of the material " or object that we have affected it " reflect them because of the iregularity of the surface like in concret .

In this tutorial of chaosgroup Material part 2 he used the reflectivity map and set it as a texbitmap in both highlight glossines ans reflection glossiness . and for the the wall texture he used a fresnal for the reflectivity glossiness .
http://www.youtube.com/watch?v=ygvBfeK2HHY&feature=mfu_in_order&list=UL

Does someone can expaline to me where can i put exactly the speculartiy map and why ?

here in the image the specularity and glossy are specified as 50 %. but in fresnel we write 1.55 or something like that. how are the percentages written on arroway website then considered?

stefanq · 10 Sept 2012, 16:44

John, 50% means 0,5. Default is 1. So if u use a map in reflection glossiness, use 0,5 glossiness, NOT texture multiplier.
Since I jumped into this, I did some experiments based on my experience, so that doesn't mean that are 100% correct.
I'm using HDRI map in both GI Color and BG Color , IM and DMC,physical camera disabled .
I have bump map with 0,01 multiplier. Reflection glossiness and highlight glossiness always set to 1.
Image 1
I just added reflection layer to the material, with 1,55 Fresnel.
Image 2
I added the specular map to the perpendicular slot of the Fresnel. Note how nice the bump of the material is now defined (the bump is the same, 0,01)
Image 3
I added the same specular map to the Reflection Glossiness slot.
This is where I usually stop. Adding the map to the highlight glossiness doesn't seams to affect the look of the material.

john2 · 11 Sept 2012, 05:07

@stefanq said:

John, 50% means 0,5. Default is 1. So if u use a map in reflection glossiness, use 0,5 glossiness, NOT texture multiplier.
Since I jumped into this, I did some experiments based on my experience, so that doesn't mean that are 100% correct.
I'm using HDRI map in both GI Color and BG Color , IM and DMC,physical camera disabled .
I have bump map with 0,01 multiplier. Reflection glossiness and highlight glossiness always set to 1.
Image 1
I just added reflection layer to the material, with 1,55 Fresnel.
Image 2
I added the specular map to the perpendicular slot of the Fresnel. Note how nice the bump of the material is now defined (the bump is the same, 0,01)
Image 3
I added the same specular map to the Reflection Glossiness slot.
This is where I usually stop. Adding the map to the highlight glossiness doesn't seams to affect the look of the material.

thanks a lot for clearing my doubts. image number two is really sexy!!. can you share the hdri map please? i have tried many times to change the environment to something realistic but my renders always look poor. i have to definitely learn about hdri to have quality renders. thanks again.

stefanq · 11 Sept 2012, 09:16

You're welcome, unfortunately I can't share it, because it is commercial, but you will find free hdri with amazing quality here: http://www.openfootage.net/?cat=15

john2 · 11 Sept 2012, 09:24

@stefanq said:

You're welcome, unfortunately I can't share it, because it is commercial, but you will find free hdri with amazing quality here: http://www.openfootage.net/?cat=15

okay, just tell me the name. that'll help me find a similar free one .

hdri are light settings right? e.g. how the lighting would be in a mountainous region etc.?

redot · 11 Sept 2012, 11:19

Thank you Stefan,
This is an issue I have often wondered about.
And now I know!
Thanks again.

john2 · 12 Sept 2012, 06:25

another great tutorial here...

http://sketchupvrayresources.blogspot.in/2012/03/basic-vray-sketchup-tutorial-series-4.html

andybot · 19 Sept 2012, 23:07

@stefanq said:

John, 50% means 0,5. Default is 1. So if u use a map in reflection glossiness, use 0,5 glossiness, NOT texture multiplier.
Since I jumped into this, I did some experiments based on my experience, so that doesn't mean that are 100% correct.
I'm using HDRI map in both GI Color and BG Color , IM and DMC,physical camera disabled .
I have bump map with 0,01 multiplier. Reflection glossiness and highlight glossiness always set to 1.
Image 1
I just added reflection layer to the material, with 1,55 Fresnel.
Image 2
I added the specular map to the perpendicular slot of the Fresnel. Note how nice the bump of the material is now defined (the bump is the same, 0,01)
Image 3
I added the same specular map to the Reflection Glossiness slot.
This is where I usually stop. Adding the map to the highlight glossiness doesn't seams to affect the look of the material.

Stefan, thank you very much for this instruction! That's a great suggestion adding the specular map in the perpendicular slot of the Fresnel texture. Really helps the realism.

Andy

john2 · 20 Sept 2012, 05:34

i get that .5 means 50 percent. and what does 1.55 in Fresnel mean?

andybot · 20 Sept 2012, 12:24

@john2 said:

what does 1.55 in Fresnel mean?

The Fresnel value is for the IOR (Index of refraction) - it's the cosine of something or other... see if you can decipher the wikipedia article

john2 · 21 Sept 2012, 05:51

@andybot said:

@john2 said:

what does 1.55 in Fresnel mean?

The Fresnel value is for the IOR (Index of refraction) - it's the cosine of something or other... see if you can decipher the wikipedia article

yup i know about index of refraction since a long time [thanks to all my class 9 physics lectures ] you really gave me a deja vu

i'm talking about Reflection.

Im aware that IOrefraction is

sine of angle of incidence in air

divided by

sine of angle of refraction in the material

andybot · 21 Sept 2012, 08:50

@john2 said:

i'm talking about Reflection.

similar principal applies - the ior sets the strength of the reflection based on the angle of incidence.

john2 · 21 Sept 2012, 11:04

@andybot said:

@john2 said:

i'm talking about Reflection.

similar principal applies - the ior sets the strength of the reflection based on the angle of incidence.

uhhuh...can't figure this. the angle of light changes when it travels from one medium to another, that's why the bending occurs. but according to the law of reflection. angle of incidence is equal to angle of reflection.

ATLAStudio · 21 Jan 2013, 13:59

Thanks Stefan for your tips on map slots, been very useful! I managed to cook this up following your advice and Bertrand Benoit's 'materialism' post.

To clarify on the percentage contribution of the glossiness, I've found that once you plug a map into the glossiness slot this overrides whatever figure you use. In the example below is the same material with spec map and glossiness set to 1.0, 0.8 and 0.2 from L to R, it's not a great example scene but you can't see any diminished reflection as a result of the map being 'darkened'. If you drop the texture multiplier however, it blurs the whole thing rather than reducing the contribution of the map alone (shiny cube example), which means you have to go into photo editing software to finetune the map. This is a bit frustrating, if anyone knows a workaround within vray settings please share!

andybot · 21 Jan 2013, 18:32

did you make sure the specular map is in the perpendicular slot of your fresnel reflection options? If it is in that location, then glossiness will be affected.