Bump map not showing differences for different height

Question

I've tried three cubes with different height, and render the height map in Render View Image, the upper one is the height map, the lower one is a plane with the rendered height map.

From top-down view,

From side view

My question is why there is no difference when the height map is applied, my node steup is like this,

Edit:Slope doesn't help too much for the height, I can't tell the difference either.

There is only so far a bump map can trick you into believing there is an actual displacement. Try lowering the distance and / or strength of the bump node. Also, the illusion comes from the slope, not the actual bright value. Try to use a gradient for your bump map between dark and bright values — Gorgious, Feb 22 '21 at 07:15
This might be working, to get better illusion a gradient slope should does the work, I will be doing some trials. — user3505400, Feb 22 '21 at 07:24
How do I add the depth to the map can you shed some light on it — user3505400, Feb 22 '21 at 07:44

jachym michal · Answer 1 · 2021-02-22T10:06:48.353

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I'm not sure the Z depth value is helpful here.
I used this Robin Betts' answer for the height map instead

Render the height map
Set Bump Distance to correspond to your object's max height (0,5 m in my example)
Done

^{Geometry with 0,5 meters max height}

^{Generated Height map}

^{Bump Distance with 0,5 m height}

edited Feb 22 '21 at 10:06

answered Feb 22 '21 at 08:56

jachym michal

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While I created height map from the Z position, the black and white picture shows the difference, but no difference under render view, heightmap should've had height information – user3505400 Feb 22 '21 at 09:15
I'll edit the answer to use the same geometry as your Q :) – jachym michal Feb 22 '21 at 09:58
How do you render the height map? Just place the camera above and hit render? And couldn't you directly render a Normal map? Or is that not worth it? Should I then still rout it trough a Bump map or directly into the normal? – Phönix 64 Feb 22 '21 at 10:27
Yes, I put an orthographic camera there and simply rendered. Baking a normal map would probably give better results (it has more information), but the Q is about bump maps :). – jachym michal Feb 22 '21 at 11:38
Thanks @JachymMichal I am now trying your solution wish I would get better result – user3505400 Feb 22 '21 at 12:52
@JachymMichal can you share your node setup, I use geometry to extract Z value, I got the result nearly the same as before, which I think bump map can only going so far, not what I expected – user3505400 Feb 22 '21 at 13:57
@JachymMichal You said normal map contains more information, why is that, bump map has height info which normal doesn't, you can place a cube on the plane and normal map doesn't even show that cube cause all angle points upwards – user3505400 Feb 22 '21 at 14:00
Hello @user350 :). Bump map only uses one Black/White channel, Normal maps use all three RGB channels.. Bump maps are simpler to create/use/calculate, but have considerable limits. It's an older way of adding details. – jachym michal Feb 22 '21 at 14:16
@JachymMichal But normal map doesn't have height info while bump has, normal can not replace bump as they serve for different purposes – user3505400 Feb 22 '21 at 14:53
Hey @user350 :). Blender Stack Exchange: Bump Maps vs Normal Maps – jachym michal Feb 22 '21 at 15:18
I've read the linked answer before, but still no explain for why normal have more information over height map, cause height map does have information which normal map doesn't. – user3505400 Feb 23 '21 at 15:01
Let us continue this discussion in chat. – jachym michal Feb 23 '21 at 16:39

score 0 · Answer 2 · answered Feb 22 '21 at 09:01

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In this case, you should use Displacement. First, you need enough geometry. So put a subdivision surface modifier on the mesh and crank it up then you can go into the Material tap and under settings in surface change the Displacement to Displacement Only. Then replace your Bump node in your material with a Displacement node and then feed it into the Displacement.

answered Feb 22 '21 at 09:01

Phönix 64

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This is a solution however I want to know why the identical looking when different height is applied – user3505400 Feb 22 '21 at 10:03

Bump map not showing differences for different height

2 Answers2