Render bump/offset map

[PhilippeV8]

I was wondering ... I have a 3D model with fine detail on a plastic part ... but it's heavy to work with and in the end it's not shown in a render from close-up (If I need such a render, i'll use the high detail 3D) ... so i'd like to make a simplified part that is just flat, then add a bumpmap with the details.  So if we have the detailed 3D model, is it possible to "render" a good working bumpmap of it ?  What lighting to use, what colors, etc etc ?

[DriesV]

Hey Philippe,

Here is a technique I sometimes use to generate normal maps from geometric detail.

- Import the (preferably tilable) geometric pattern in KeyShot
- Position model and camera such that Standard View Front is looking straight at the pattern (Azimuth -90° / Inclination 0°)
- Make sure the camera's lens type is set to Orthographic to avoid perspective distortion
- Render the scene with Geometric Normal Pass
- Open the Geometric Normal Pass in Photoshop
- Use attached Photoshop action (Normals - convert EXR.atn) to convert the pass to something that can be used as a normal map
- Optionally: Crop the image to make it tilable

Attached normal map Simple Thread Plate_normal.png was generated from model Simple Thread Plate.step.

Dries

[DriesV]

Left: original geometry
Right: plane with converted normal map

Dries

[bdesign]

This is great, Dries. Thanks very much for sharing the file and the Photoshop action!

Cheers,
Eric

[DriesV]

Hi Eric,

You're welcome.
Let me know how it works. It is possible that this technique can be improved a bit. I have noticed some dithering after the 32 bit to 8 bit conversion.  (i.e. There is some noise in the 'flat' purple areas when applied as a normal map in KeyShot.)

Dries

[NM-92]

Nice approach ! Really useful

[PhilippeV8]

Here's what I came up with in the meantime ...

Created a custom HDR environement.  Component texture is 10% gray.  Environement contrast up at 1.388 brightness down to 0.145

Attached is the HDZ file and the output result I get.  I used this as a bumpap.

[PhilippeV8]

Render results ... which is which ?

[DriesV]

Hey Philippe,

Workable approach too. 
I see you have some shadowing on the diffuse material, which you probably will want to avoid.
Perhaps it works even better if you disable Self Shadows. Or enable Performance Mode.

Dries

[DriesV]

Btw, we are looking into adding geometric normal pass output that can directly be used as a normal map.

Dries

[DriesV]

UPDATE:
I re-uploaded the zip archive in my first post. I replaced the converted normal map and Photoshop action.
In the original version, I inverted the green channel, which isn't necessary.

Dries