Tutorial bump map?

Tutorials/guides/tips on how to use Indigo and the Indigo exporters
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Nick
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Tutorial bump map?

Post by Nick » Sat Aug 22, 2009 3:46 am

Hello guys, i dont found one tutorial of bump map!!!

Now for create bump map, i use photoshop and i open the texture file and after i hide saturation...this is the correct procedure???

If yes, early i will create a little tutorial!
If no, suggestions are welcome!!


Nick

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Godzilla
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Re: Tutorial bump map?

Post by Godzilla » Sat Aug 22, 2009 4:04 am

You'd be better off just using the diffuse map as the bump map, if that's all that you're doing. There would be no noticeable difference.
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Pibuz
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Re: Tutorial bump map?

Post by Pibuz » Mon Aug 24, 2009 10:33 pm

Nick, ANY texture can be used as a bump map.

As Godzilla said, you could set the bump drop down menu on "SketchUp" and you'd get almost the same result as if you converted the SU texture to greyscale in PS.

The PS passage helps you to make the texture more suitable for your needs, adjusting the contrast, the levels, the brightness. This way, you can optimize, select, accent the bump (or the specular) zones at your will.

I attach the maps used for the floor mat in my memorial scene.
I hope this clears up a little their usefulness. :wink:
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Re: Tutorial bump map?

Post by madcoo » Mon Sep 07, 2009 8:54 pm

Hi guys!

Can I check with you I've got it all right?

In a BUMP MAP = dark areas are supposed to be the "deeper" parts of the texture.
(for example in a parkett Bump Map the dark areas are situated in the "veins" of the wood and between each plank of wood)

In an EXPONENT MAP = dark areas are those supposed to be less shiny than the others.
(useful for unevenly reflective surfaces)

In a DISPLACEMENT MAP = lighter areas get more displaced than dark areas.

Am I right???
:?
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CTZn
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Re: Tutorial bump map?

Post by CTZn » Tue Sep 08, 2009 12:33 am

That's all correct madcoo !

Here are some details, I hope they will help for clarification, as opposed to confusion :)

Bump maps, exponent maps, displacement maps are called "scalar" maps. Blend maps also, off the top of my head.

Why scalar ? Because their data is not used for a direct visual effect, like they would for albedo or specular reflectivity for instance.

They are just providing a multiplier (changing over the surface) to control a given shading parameter. As you know, for an uniform effect over the surface, no need to create an uniform map, a single float value is enough (that's common for materials blendind).

So, "scalar" because they often just give the scale, or variation, of the parameter. The "b" value of the texture is giving the maximum allowed value of the effect; b-c is the real amplitude of the map as a whole.

You can indeed understand that darker pixels will code for a smaller value of the parameter.

Practical example (displacement):

We want to evaluate the height of a displaced surface directly above a given pixel of a texture. That pixel is, say, 48% grey. The map "b" value is 0.016 (meters), it's "c" value is 0.004.

The displaced height above that pixel will be:

Code: Select all

(0.48 x 0.016) + 0.004 = 0.01168 meters
You can see that the texture (= file) is giving only one of the three terms of the equation. The whole thing is the mapping for a control, namely displacement.

This is how Indigo handles texture files in most cases, if not all. Hopefully you can now predict the effects of complex parameters, like the above.

Or, that will come ;)
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madcoo
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Re: Tutorial bump map?

Post by madcoo » Tue Sep 08, 2009 1:05 am

This is just a BRILLIANT explanation, many thanks for that CTZn!!!
:D

I always wondered what the "a", "b", and "c" values were, now I know a little more!!!

This way, when I want the "veins" of the wood to be - let's say - 2 millimeters high, I'll be able to work out what values I need to put in!!!

Great, many thanks again!
:D

EDIT: What's the "A" value then???
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CTZn
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Re: Tutorial bump map?

Post by CTZn » Tue Sep 08, 2009 4:44 pm

EDIT: What's the "A" value then???
I don't know that :)

I'm used to believe it's a gamma setting but I didn't test the thing out tbh.

EDIT:
below, madcoo wrote:Ok thanks!
:wink:
Here's my theory, please exercise caution with it:

The texture "A" parameter could be a modifier for the texture gamma, zero leaving it unchanged, positive values augmenting it, and negative values reducing it, obviously.

I would use details in plain english myself...
Last edited by CTZn on Tue Sep 08, 2009 6:34 pm, edited 1 time in total.
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madcoo
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Re: Tutorial bump map?

Post by madcoo » Tue Sep 08, 2009 6:13 pm

Ok thanks!
:wink:
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CTZn
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Re: Tutorial bump map?

Post by CTZn » Tue Sep 08, 2009 6:49 pm

See edit above...

Another tip:

you can control the textures saturation by reducing the b parameter, and setting the c parameter so b+c=1 (at a maximum or it will burn out, lower b+c values are acceptable).

No image editor hassle, and gain in flexibility ;)
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madcoo
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Re: Tutorial bump map?

Post by madcoo » Tue Sep 08, 2009 7:23 pm

I still have trouble getting what "texture saturation" is...
:?

Feeling dumb right now...
:mrgreen:
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CTZn
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Re: Tutorial bump map?

Post by CTZn » Wed Sep 09, 2009 2:29 am

Heh...

:oops:

It's how I call "luminosity" when I'm overzealous :mrgreen:

My bad madcoo, don't feel confused.
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madcoo
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Re: Tutorial bump map?

Post by madcoo » Wed Sep 09, 2009 6:30 pm

:lol:

No worries CTZn!!!
Now I get it!

Thanks for your clear and highly helpful explanations!
:D
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dakiru
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Re: Tutorial bump map?

Post by dakiru » Tue Sep 22, 2009 4:40 am

CTZn wrote:That's all correct madcoo !

Here are some details, I hope they will help for clarification, as opposed to confusion :)

Bump maps, exponent maps, displacement maps are called "scalar" maps. Blend maps also, off the top of my head.
...
This explanation is awesome! Thank you very much! :D

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madcoo
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Re: Tutorial bump map?

Post by madcoo » Wed Oct 28, 2009 4:04 am

CTZn wrote:The "b" value of the texture is giving the maximum allowed value of the effect; b-c is the real amplitude of the map as a whole.
:?
I'm a bit puzzled... again...
Sorry!
:oops:

=> If the B value is the maximum value allowed for the effect, what's the point in adding another parameter (the "c" value)???
Sorry I really can't work it out!!!
:wink:
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madcoo
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Re: Tutorial bump map?

Post by madcoo » Wed Oct 28, 2009 4:09 am

Maybe adding a "c" value to -say- a 48% black pixel, will tell Indigo that:
- the max value for displacement will be the "b" value,
- EXCEPT for all 48% black pixels (and only them), which will be "higher" than the others (by a value of "c")

:?: :?: :?:
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