Gradient Ramp brighter than 255

[andrewjohn81]

I've got a front loading washing machine and I want a nice little reflection across the glass. You've seen the type. Usually found on images of computer monitors, tv's and cell phones.

So I created a black and white gradient that looks like how I want it and put it in the environment slot. Maybe that's my problem, but I'm not sure.
can you maybe not have something with an explicit map in the environment slot?

If I render without changing the output, then it looks fine. If I change output amount, rgb offset, or level, I get this strange lined pattern that would remind you of a moire pattern.

any ideas?


(i would love to post an image, but I can't through this proxy as pretty much all image posting sites are blocked).

[vlado]

You should use spherical environment mapping rather than explicit map channel for environments. Overbright colors should not be a problem for V-Ray, but I'm not sure about the Gradient Ramp texture itself.

Best regards,
Vlado

[^Lele^]

that is because you "stretch" the 8 bit values, introducing banding.
Try texture mapping the gradient ramp with overbright vrayColor maps, and it should work the treat.

[re:FORM]

Sorry to hijack this thread a bit, but... lele, do you know if there's any way to get more than just 100 points on a gradient ramp? Its great having float colour now, but it would be even better to have float precision on the gradient itself!

[instinct]

what i did with success was simply right clicking swatches and add a vraycolor as a swatchmap in the gradient ramp

worked fine for me...

Regards,
Thorsten

[^Lele^]

afaik, no, that's a limit which is hard-coded in the map.
The only, very laborious way I can see, is to nest gradient ramp maps inside the points, but it's a hell of an headache.
Possibly scriptable...

[percydaman]

giggity, I smell a script coming...

[instinct]

given the headache i dont.... :P :P :P

[re:FORM]

Yea... I wonder.. if beyond the fact the map is hard coded that way, that there isn't another reason why they haven't updated the map. Is it because max maps generally aren't float yet?

Maybe we should stick a vray-gradient-map into vlado's wishlist inbox ? Although I think the demand for such a map is fairly limited.

[andrewjohn81]

I know environment mappping is generally built for spherical environment maps, but couldn't I use explicit maps instead? What would be the problems that might occur.

Basically the problem is I want a reflection on the glass on the front, but nothing else. It would be nice if I could have an object reflect in the glass, but not be reflected by anything else. That way I could just apply the gradient to a plane in front of the glass to match what I want. That's really what I want. I'd apply the gradient to opacity and put an overbright vray color in the diffuse, if needed. That way the glass could continue to reflect the environment where the gradient isn't matching the rest of the unit.

[^Lele^]

I know environment mappping is generally built for spherical environment maps, but couldn't I use explicit maps instead? What would be the problems that might occur.

That your map would traced as if it was overlayed on top of geometry, rather than properly reflected.
For the issue with individual reflections, do use compositing.

[andrewjohn81]

I know the reflection wouldn't be right, but if the darn thing is in a completely white environment reflecting a different environment it's already "wrong" anyway. And I'm not animating it. It's just a still.

We usually do this in photoshop without any additional renders, but then we are kind of lying about the actual shape.
I suppose I could do just a reflection pass with just the object I want and composite only that, but doesn't that just seem like quite a bit of unnecessary work for one single image?
In the time I set up the render I could have drawn the thing in photoshop. I was basically just hoping to get the same faked results in vray so I could skip a step but show the curve of the glass more effectively.