Reflection - working with falloff maps, fallof curves, curve types for certain mats

[PIXELBOX_SRO]

Hi,
I ve been wondering whether there is some sort of literature of tuts on working with falloff curves in regards to the type of the material??

I ve seen some really mental (meant in a good way) curve types in Alex Romans Exeter building tutorial and i just wonder how he came up with such shapes and values?

Have i missed some basic tut somewher or some important piece of know how on this matter?

Thanks for any info

Best Regards

[joconnell]

Pretty much just style really? Ior is all very well but it's not going to give you the exact look of a material you want - since the look of a material, especially a shiny or reflective one, is a combination of it's settings and the lights and environment around it you'd spend a lot of time trying to get the exact result you want. With a falloff it's just a dumb curve you can adjust easily so if you've a photograph of an object you're trying to match or just want a little bit more artistic control over how the reflection on something rolls off then falloff is really handy. There's no technique involved in it as such, it's all dependant on the shape of your object (since you're dealing with how the material changes between front and side) and your scene which is always different. It's very handy for print and product shots when you want to tweak how a tiny bit of a reflection warps around the side of an object for example.

[PIXELBOX_SRO]

i get you ....i was just wondering whether that curve Alex applied was by experience or by some sort of material settign know how or guide that could be found somewhere

[joconnell]

Not really - I take it you're talking about the level of reflection on the concrete walls? To be honest I think it's a choice of style more than anything. For example if you look at the right of this wall, you get plenty of reflection further away at the window but it gradually dies away as it comes towards us - similar to the look of the exeter stuff.



You might find having that amount of reflection on your walls would be far too strong over all so having a falloff curve means you can tweak it to have a very high level of reflection just at the window but die off fairly quickly afterwards. Personally I find it really handy to temporarily put the falloff map into the main slot of a vray light material and render a single frame so you can quickly tweak how it's fading between white and black for the angle you're rendering from, then put that back into the reflection slot of your main vray material. Anything you can do to give you faster render feedback or more predictable results is worth doing in my book.

[Da_elf]

i think the major question is if his settings are based on a document out there that lists real falloff for different materials or were arrived at via trial and error, long time experience, or just a good material library used over and over again

[PIXELBOX_SRO]

Thanks for your insight and tips Joconnell!!! I have to try this vraylight material tip!

Da_elf: Yes, thats what i meant in general

[joconnell]

Ah I getcha - Cheers Elf.

I've found over the years that any tables of values for material IORS never really give you the look you want. For example if you've got a photograph of concrete that you like the look of and you go along to your table of IOR values and input the correct value, you probably won't get something that looks the same as what you saw in the photograph. Personally I look for photos of the material looking pretty then try and replicate that using a generic ior to start off with (normally I start between 2.5 - 4) and if that looks fine then brilliant, job done. If I find that the way the reflection falls off around the object isn't quite as pretty as I'd like or if I want to get a specific level of reflection on a specific area of the object, then I'll start using falloff. Since falloff is a little bit hard to judge without doing renders, I'll often either use the vray light material method or sometimes turn on the reflection filter render element - that'll give you a black and white render which shows how much vray is using of the reflection on each object in the scene - good if you want to check how much of a contribution your reflection makes.

[PIXELBOX_SRO]

great tips...speaking of falloff....what do you prefer to use? CAMERA/DISTANCE of PERPENDICULAR/PARALEL
let say youd want to match the reflection on that image sample you ve posted???

[joconnell]

Definitely perpendicular / parallel. Camera / distance can't be used as easily on other objects at different positions in your scene.