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  nephilim's Advanced Normal Map Tutorial  
This tutorial has been written by nephilim, for questions, suggestions or any other comments head over to the dedicated BI Forum Thread.
It has been reviewed and some minor spelling mistakes have been corrected by ArmedAssault.info :

Ok, lets's start here.

This friday, I'll show you how to create and enhance your photo-sources normal maps.

I'm gonna start simple, here´s what we´ll use.

View High-Res


Nice gravel :)

The texture can be found on mayang.com/textures. Usually people seem to take a photo and run it through the normal map photo shop filter and the result will usually look like this:

Photoshop:

View High-Res



3dsMax, Normal map only:



3dsMax, Normal and Diffuse:


Doesnt look really cool huh? More like a cheap wallpaper you can buy in your local walmart.
But why is that so?

Lets take a deeper look into the source image.

For that we desaturate it.

View High-Res


Ok now the pic´s black and white. And now it tells us quite alot!

Normal Maps are commonly refered as bump maps on steroids.
Especially if you create them via photoshop. Generally speaking white areas are the peaks and dark areas are the valleys.

As you can see in the image some stones are black. It would make much sense having these caving inside whilst their actual geometry is described with a convex shape.

Ok, so how to we solve this?

Increase the samples in the plugin? Hm lets try this:





Looks better but still they appear flat

So what do we do??

We are going to do what the plugin does but we'll do it manually! MANUALLY?? Yes indeed, manually!

But we´ll use some trickery to get what we want :)


Ok as I said earlier, the B/W image tells us alot about the geometry.
BUT since some things like stones (or whatever) can be black we´re having a problem :/
So what now? Hang us? No....

Open up your image in Photoshop and then click on :
Image>Mode> LAB-Channel.


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Q: Ok what the heck is LAB channel???

A: Lab channel is something quite nice, it saves us a luminocity channel!


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Do you see the difference?

Some might say hey I could crank up the brightness to get that. Well, ... it might work in some cases in others it won't.
That is my approach and you are free to follow or not.

But there are still some stones that are dark due to their color.
And we do not want that because we aim for it to get something similar to a Bump Map, that just describes the height! So we need to elimate these folks :)


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For this I took the LAB channel and pasted it into a new image, and then collapsed it down and converted into an average RGB.

Also as we just want to describe the actual geometry I blurred the image a bit to get rid off all those small nooks and crannies. We will need them but not right now.

The next step is to basically paint over some stones, preferably the dark ones to give them more height.
You can use the dodge and burn tools or just paint with black and white and blend them, what ever serves you.
I also cranked the contrast a to get better peaks and valleys.


View High-Res


Alright done ,but wheres the normal map fun??

Here it comes :

Save that B/W image and run the normal map filter with it
I used these settings :
-height generation :4 sample
-scale 5
-height source: average RGB

Anything else isn't important.

Ok now we have a normal map and it looks cool but still not awesome :)
Here comes the trickery. It's simple if you know how to do it and its not really magic.

What you do is the following.

duplicate, set blend mode to overlay, blur,
duplicate, set blend mode to overlay, blur,
duplicate, set blend mode to overlay, blur,
duplicate, set blend mode to overlay, blur,
duplicate, set blend mode to overlay, blur,
duplicate, set blend mode to overlay, blur,
etc etc.


Yes thats all!

Duplicate copies the normal map and setting it to blend mode somewhat doubles the "height"
blurring and allows you do get smoother transistions.

Now that youve youve done this, merge all layers down and eventually use the smoothing brush to get some nasty edged stones smooth.

Ok now we have a geometry describing normal map, but it doesnt have any detail! all the scratches are gone! NEPHILIM IS A LIAR *DIE**HATE*!

Remember the other crappy normal map we got previously?

Load it up and copy it into the "cool new" normal map and set it to overlay blend mode

You'll get this:


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Now that looks cool, and much better than the crappy normal map we previously had.

As a last step we merge it all down and fire up the normal map filter again and go into:
Alternate Conversions and set it to Normalize only.

During the copy/paste/blend process some channels get messed up slightly,and this option fixes it. So dont forget that!


Heres how it looks in action:

Just the diffuse, normal map, and some hard specularity to get a wet look:


DOWNLOAD - High-Res Video (finished)


no magic, no clumsy messing with the normal maps channels

I admit I could've done better with this normal map, but i just want to give you a glimpse on what can be done with some extra effort!

Remember!´Layer your normal maps and blend them with other images and you´ll get far better results!

Here´s another texture ive done on the fly using the similar technique.

Bad :


DOWNLOAD - High-Res Video (bad)



Good :


DOWNLOAD - High-Res Video (good)




This tutorial has been written by nephilim and was revised by ArmedAssault.info
  December 26th, 2007 - 20:25   Comment (0)  

 
 
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