Min distance for vray dirt?

[joconnell]

Heya folks!

We do a tonne of dirty surfaces and weathering in work so we rely on vray dirt quite a bit for masks. One issue of course is when you've got a large object that has some small details or shallow surfaces, a radius setting that works well on the large parts will leave the small parts totally filled with dirt. Do you think it'd be possible to do something like have a minimum distance parameter or some kind of ramp control where we'd be able to not consider polygons that are closer than a specific distance? Or perhaps some kind of control curve between 0 and the radius value so we'd be able to turn down the strength of the closer areas?

There's some other solutions available for this in 3dsmax of course but I'd love to keep everything within the development environment of chaos where speed and memory handling are constantly improved, plus it'd be great to have the same options in other applications which we have vray licenses for!

Cheers,

John

[denisg]

Could not agree more. This would be a huge feature. Great post

[vlado]

Can you show me an example?

Best regards,
Vlado

[joconnell]

Righty! So here's a poly model with thin and thick bits and it's dirt settings. We definitely want the dirt on the tick sections of the model to use as our mask but if we use a large radius then all of the thin parts get completely covered. We can use a second vray dirt with a radius that works well on the thin parts and put it into a composite map but there's no way to get the big bits without affecting the small bits currently. I was thinking that similar to how the graphs in phoenix work for things like mapping temperature values to colour or smoke density to opacity, would it be possible to keep the ray distance while shading is being calculated and then have another curve control in the vray dirt texture, maybe a 0 to 1 range that automatically maps itself from 0 to whatever dirt radius you have and acts as an opacity control for the rays? With that we'd be able to take down the contribution of the close rays in the thin parts to 0 and leave the large radius rays untouched? Or perhaps the curve would be effective enough that we could find what point along our curve our thin rays lie at and leave some of them on and remove the need for multiple dirt maps?

[joconnell]

So kind of what I mean is here's a load of cylinders, kind of like rays, with their wirecolour mapped to the height of each cylinder. If you could do something similar as an option within vray dirt, like maybe even have it output ray distance as a normalized black to white value, we'd be able to use it to drive a gradient ramp and use it as a mask for both thick and thin areas. The same thing goes for curvature too - in it's present state there's no way to get either convex or concave on it's own so it's not that useful. If you made a single change to have convex values be black, concave values be white and everything in the middle being shades of grey (and ideally a min / max value) then we'd have something really useful to drive edge masks!

[rikou]

+1 !
It would be really great !

[gadzooks]

Would love to know how to use the Vray Dirt material as a mask? Is it used with a composite map or a standard Vray material? And if so where is the Dirt Map used (what slot is it plugged into)?

[Ihno]

+1 great idea!

[joconnell]

Would love to know how to use the Vray Dirt material as a mask? Is it used with a composite map or a standard Vray material? And if so where is the Dirt Map used (what slot is it plugged into)?

There's a tonne of ways to use it since by default it just outputs black and white values. The most obvious texture is the mix map where you have two different colours or textures and then a third slot for a map to use as a mask - white values give you one of the two colour maps, black gives you the other. Alternatively you can use the composite map. at the right of each layer is a button to choose another map as a mask, you can put your dirt in here. Lastly the dirt map itself has a map slot for each of the two colour swatches so if you only want to mix between two textures you can do it in there instead.

[gadzooks]

There's a tonne of ways to use it since by default it just outputs black and white values. The most obvious texture is the mix map where you have two different colours or textures and then a third slot for a map to use as a mask - white values give you one of the two colour maps, black gives you the other. Alternatively you can use the composite map. at the right of each layer is a button to choose another map as a mask, you can put your dirt in here. Lastly the dirt map itself has a map slot for each of the two colour swatches so if you only want to mix between two textures you can do it in there instead.

Thank you Sir!

[denisg]

So kind of what I mean is here's a load of cylinders, kind of like rays, with their wirecolour mapped to the height of each cylinder. If you could do something similar as an option within vray dirt, like maybe even have it output ray distance as a normalized black to white value, we'd be able to use it to drive a gradient ramp and use it as a mask for both thick and thin areas. The same thing goes for curvature too - in it's present state there's no way to get either convex or concave on it's own so it's not that useful. If you made a single change to have convex values be black, concave values be white and everything in the middle being shades of grey (and ideally a min / max value) then we'd have something really useful to drive edge masks!

Yes!!!

This concept of normalizing distance so it can later be used to drive a gradient is exactly what's needed. Perhaps less intuitive for newcomers, but vastly more powerful for the experienced.

I second everything JoC said. Including separating convex from concave in curvature. Could also move to an RGB gradient which can then be decomposed for cov. conc. flat with a color channel node.

I just want to say, with some work Vray dirt could be the single most powerful and useful map in the tool chest. Unfortunately, currently, the limitations mean that it often goes unused.

Hope this gets on the priority board. Could be so useful.