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RockstarKate
03-20-2008, 09:36 PM
I need to get a tiny concave dent to show up in my render of a very shiny and reflective black plastic object. The dent is concave and has a very, very shallow curvature. There are no sharp edges.
So far, I am using Max 2008 and Mental Ray. I'm using the Arch and Design material. I'm able to see the dent if I position the light so the specular highlight shows up right at the edge of it, but this is very difficult to do!

Just for an idea of scale- imagine a dent that is has a radius of .25mm and maximum depth of .05mm. The surface is 100X that size.
Anybody have any suggestions for me on how to make my renders capture this detail? Lighting, material, render setting suggestions would be most welcome. The material must be very reflective, much like flat car paint (no speckles)
Marcel
03-21-2008, 09:01 AM
You can make the dent with a bumpmap.

If the material is very reflective then you need to give it something to reflect to make the form visible. Place white cards in your scene at strategic places so that the the dents show up.

The material of the whitecard should be very bright. You can do this by clicking on the 'self illumination' color and fill out a very high number in the 'Value' field. This wil make the white card much brighter than a normal white surface, as if it was a lightsource (it won't emit light though, I'm just talking about how it shows up in the reflection.)
RockstarKate
03-21-2008, 12:57 PM
Is it possible to measure the depth that will be simulated by a bump map? I thought of doing it that way, but I have to compare the appearance of 2 different dents of specific depth.
I will try the white card idea, thank you.
Marcel
03-21-2008, 02:11 PM
Is it possible to measure the depth that will be simulated by a bump map? I thought of doing it that way, but I have to compare the appearance of 2 different dents of specific depth.
I will try the white card idea, thank you.

Bumpmaps are just a simple cheat, so you can't easily say how 'deep' the dent is. Just eyeball it until it looks ok :)
playmesumch00ns
03-22-2008, 01:00 PM
I'd suggest using a good captured HDR reflection map. Just key it to rotate 360 degrees around your object, render a sequence, then choose whichever angle shows off your model best and robert's your mother's live-in lover
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03-22-2008, 01:00 PM
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