Looking to learn from an experiment

[bob.bernstein]

Hi all, I've always been a hobbyist user, and mostly worked on low poly models, I'm exploring the world of high poly modeling, and having a ton of fun.  Of course I'm dealing with things I've never done before.  Last night I tried an experiment.  I'm making a headlight lens, and I've been dissatisfied by the appearance of a bump map (gamma at 1.0) wired into the bump map channel of a physical material.  Otherwise default thick glass preset.

I took that same bump map and wired it into the emission channel.  In the viewport the entire lens blows out in massive appearance of light.   In the Art renderer, instead of seeing light, it just appears to enhance the contrast of the bumps.  Kind of what I was looking for.  

Max 2017, scene light is a daylight system.  Renderer is ART.  Material is physical with bump map.  Bump map was made in Photoshop by just painting the areas of desired bump to be white.  Attached are two images, one with just the bump channel, the other with both bump and emission changes getting the bump map.

I'd enjoy hearing from the pros why I see what I see, and hear alternatives to the emission channel for make the bump map easier to see in the renders.

[Alfred.DeFlaminis]

Hello @bob.bernstein,

Interesting.  From the screenshots the key light seems to be leaving highlights but not lighting the scene much, a lot of the lighting seems environmental.  Am I off base there?  When I try to use a Daylight System with Art I get a bunch of errors, is it possible you are using the Sun Positioner?  If I created a private folder for you, could you upload the file for me to check out?  That business with emissive is a bit strange and it would be great to see the actual file.   What I think is the most odd is that the lens as it faces the camera is going totally flat which means it's not really getting hit by direct light, or at least it doesn't seem to be.  Odd.  

All that being said, displacement might help (but probably not worth it) but the number 1 thing that would bring out that bump in my opinion is giving the scene something fun to reflect rather than just the environment sky which is even and a bit boring.  (In general.)  The problem with Art is you cannot use the Sun Positioner *and* an HDRI for reflections.  So it's a bit of a conundrum.  In that case another option might be to map some HDR images onto planes and use them for reflections.  You can't mix the Sun positioner node with the HDRI in a Mix or Composite because those maps don't support it, so the reflections would have to come from the scene objects. Sometimes there are environmental overrides on materials but I don't see anything for Physical materials in that vein.  A closer look at the scene might help find a fix here.  

Best Regards,

[bob.bernstein]

Thanks AJ, happy to send the file, can you make me one of those
folders. I don't feel completely comfortable making this available to all.

I get what you said about lighting, and possibly that's really the
issue. Maybe this lens with simply a bump map would look more realistic
with different lighting. I don't know how to create the hdri image you
mentioned, although I've read about it.

I just thought it was odd that putting a map into bump and emission
pretty much eliminated the bumpiness, but showed the entire pattern flatly.

Best,
Bob

[Alfred.DeFlaminis]

Hello @bob.bernstein,

I have to agree that's a bit strange.  That's one of the reasons I thought checking the file would help to understand what is going on, thanks for sharing it and I'll stay private.  I have set up a private folder for you if you'd like to upload your files there. You should get an email about it shortly, and if you don't see it please check your SPAM folder. These files are private and will not be shared with anyone but yourself and the support staff. Please let me know if you have any questions. Please use at least an 8 character password or the Box account may not work properly.

My first hunch about the emissive issue is that since it's emissive it may not receive light and shadow at all which would break the bump since it uses the light and direction of light to determine the highlights and bumpiness.  Without any light hitting it (which self illuminated materials often don't have) it might break the bump or at least cause it not to show.  Hard to say for sure though but I'll look into it.  Thanks Bob!

Best Regards,

[Alfred.DeFlaminis · Accepted solution]

Hello @bob.bernstein,

Thanks for uploading that.  I had a chance to check it out and I've uploaded a new file.  There are a couple things that I adjusted on auto-pilot when I went in here that I think may help to resolve this.  

First, your lighting is working fine.  Things are just so reflective and I'm not so used to ART's rendering look that I didn't recognize it.  When I selected the glass for the headlight, I did see that it had a flat back with a curved front which would affect the light tracing through that shape and make it look a bit less realistic.  I turned off the tesselate modifier, deleted the back face, and put a shell on it with a turbosmooth to round out the surface and accentuate the smoothness of the lamp.  

Next I took a look at the material and noticed two things about the bump map.  First, the map itself needed to be inverted in the Output settings of the bump map.  This would allow the bump strips to poke outward instead of inward as currently it's backwards.  (From what I know about headlights.)  This also affect how the light was playing on the surface which was leading to the less than pronounced bump you were getting.  I also increased the bump value a bit to .3 instead of .1.  

From there it looked pretty good.  I tested the emissive and it doesn't seem to remove the bump anymore, but perhaps I wasn't using the same settings.  Can you take a look and we'll compare notes again?   Thanks!

Best Regards,

[bob.bernstein]

This is cool, thanks so much. All of your comments made sense, and I
can't wait til I can really dig in. Just to see the bumps inverted will
be cool. Talk more after I get to spend quality time with max, prolly
tomorrow night. I must say that the lens shape did occur to me, but I
had no idea what good looked like. The shape started as an extrude from
a circle, and then I shaped the front, never considered issues with the
back.

Bob

[Alfred.DeFlaminis]

Hello @bob.bernstein,

Thanks for uploading, it's a really fun scene.  It was fun to be in the scene and checking things out.  I look forward to your next update!

Best Regards,

[bob.bernstein]

AJ, I see how you inverted the map, first time I've seen that control.  I never really looked at the Output tab.  

I agree, your changes improved the lens totally.  The distortion of the mapping seems less now that the surfaces are parallel.  This is really fine learning for me.  Much obliged.

Bob

[Alfred.DeFlaminis]

I am happy to help in any way @bob.bernstein, keep 'em comin'!  Thanks for the update!

Best Regards,