Wednesday, 31 July 2013

BumpMapping Level II

To my surprise the 'BumpMapped Logo' tutorial got the most hits of my blog so far, which inspired me to revisit the effect yesterday.
I think there is a lot of potential in bumpmapping that is overlooked and today im going to show you how you can add some complexity to the basic technique.

The key element of bumpmapping is blurring and as all my gimp-scientist-padawans know, blur means you can shape it with an alpha-curve ! :)



01. So for our exercise, i set up a square canvas 600x600px in scientific green, with guides at 50% horizontically and vertically.

02. Create a gradient on a new tansparent layer, from white to transparent, radial shape, with adaptive supersampling ticked


03. Shape the gradient with an alpha-curve, first in a rough form and then refine.



04. Create a new layer on top of your background and below the gradient in a 50ies grey (#808080).....
turn off the gradient layer !

05. With the grey layer active, bumpmap the gradient layer and you get this "speaker" shape:


06. Next create a circular selection from the middle, save it to a channel, invert and delete from the grey layer....


07. deselect then blur the channel by 5px.

08. Activate the speaker layer and bumpmap it with the channel


Now some decoration:

01. Create a new grey layer on top of the BG.

02. Create a circular selection from the middle and make it bigger than the speaker and delete from the grey layer.


03. Create a rectangular selection from the middle and delete.


04. Repeat until you get a nice decorative shape, that you like.
I also want rounded edges, so i blur (12) and then tweak with alpha curve.


Alpha select your deco and save it to a channel for future use.

05. Duplicate decor layer, put it on top, lock alpha channel, drag white over it, unlock

06. Blur white layer (8), then turn off the eye

07. Activate grey decor layer and bumpmap

08. For more decoration, call up the selection from the saved channel and shrink (i used 26),
then fill on a new transparent layer with grey.

09. Deselect – for rounded edges repeat blurring and alpha curve


10. Duplicate, put on top, lock alpha channel, drag white, unlock and blur (12) as above for the bumpmap.

11. For a little variation we are giving the bump map a contour. Heres a reminder from a previous tutorial what contours can look like:


I used this one:


Here is a little trick, giving a bumpmap a contour and then applying the bumpmap often results in jaggy edges....
what can help is blurring the bumpmap again - 3-5px seem like good values....

then bumpmap !



12. You can repeat this forever, with texture, patterns, structures. Be creative !


For another example lets give text a contour:

Type your text.
Duplicate layer, lock alpha channel, drag white over it, unlock, then blur (i used 10), shape contour, put on top.


See how you get all ugly jaggy edges when you bump map it like it is:


But blur the contoured bumpmap again by 5px and it looks like this !




To finalize the piece i mapped a gradient on the text, played with value curves and applied anisotropic smoothing (a bit like in my Kitsch Chrome Tutorial).
On top of that G'MIC 'Light Glow'.

Added a drophadow that i displaced with the speaker bumpmap.

The blue light effect is just radial motionblur


That concludes this tutorial, hope you like it !

If you want to study what i did, here is the XCF-file:

1 comment:

Ashish Tomer said...

It's great! Thank you :)