Texture Painting - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 164

Reconciling Fixed Seams and Layered Images

Fixing Seams
With my texture for the skin nice and detailed, I
headed back to Blender to check that it worked okay
and then started fixing any seams in the texture. To
do this, I exported my skin texture from GIMP and
replaced the old skin texture in Blender with the
new exported version.
There were bound to be some artifacts in the
texture along UV seams, where I had painted over
the edges of a UV island in GIMP. To fix these, use
Blender's Quick Edit feature:

This process fixed my seams, but because I fixed the
texture in Blender, I had only a single-layer image
as a result. To get back to a layered format, I opened
the corrected image in GIMP as a new layer in my
texture file, on top of my other layers. I wanted to be
able to keep my old layers visible where possible, so
I needed to mask this layer to show through only in
those areas where I fixed the seams. To accomplish
this, do the following:

1. Set the new fixed layer's blend mode to

Difference in the Layers dialog. The result
of this blend mode is the difference between
the colors on this layer and the pixels below,
meaning that different areas look bright and
unchanged areas remain black. Overall, it may
look very dark at the moment because the dif-
ferences are slight, but you'll fix that shortly. You
can use the result as the basis for a mask that
shows only the fixed parts of the new layer.

1. To fix a seam on one part of your model, navi-

gate the 3D view to an angle where the seam is
clearly visible.

2. To make sure that no shading is visible on screen,

set the viewpoint display mode to GLSL and set
the material to Shadeless in the Materials tab
of the Properties editor.

3. In Texture Paint mode, set the Quick Edit reso-

lution to 1024 and click Quick Edit from the
Tool Shelf (see Figure 11-15 ❷ ). This opens a
screenshot of that view in GIMP, which we can
then start painting over.

2. Right-click on the top layer in the Layers dialog

and select New Layer from Visible . This creates
a new layer that is a composite of all the lay-
ers below, merged into one. In our case, this is
the difference between the fixed layer and the
original layered image. Using the Levels tool
( Colors 4 Levels ), you can increase the values
of this layer to create something we can use as
a mask. The Levels tool takes the current layer
as the input and uses the settings you provide to
adjust the values of the layer. You simply want to
take any pixels that aren't 100 percent black—
areas where the fixed image differs from the
original—and make them white. To do this, set
the right-hand endpoint of the input gradient so
that it's close to the left-hand end by dragging it
to the left (see Figure 11-16) and click OK .

4. For best results, scale up the screenshot in

GIMP, using Image 4 Image Size , and set the
new size to 2048 . Then, create a new transpar-
ent layer on which we will fix the seam (the rea-
son for this will become clear shortly).

5. Using the Clone tool, start cloning from the

layer below to cover the seam; the Grunge brush
shape works well for this. (Turning on Sample
Merged in the tool options will let you sample
from all layers when you set the source, rather
than having to switch layers first.)

6. With the seam painted out, disable the original

layer, leaving only the newly painted layer that
covers the seam. Use ctrl -E to export the image
and save over the original exported image from
Blender.

3. The results may look slightly noisy and have

some odd-looking colors, but the colors
don't matter because we'll be using only the
brightness of this layer as a mask. To smooth
things out a bit, use the Gaussian Blur filter
( Filters 4 Blur 4 Gaussian Blur ) to blur the
layer by about 10 pixels.

7. Back in Blender, click Apply to apply the painted-

over image to your texture (see Figure 11-15 ❹ ).
Because you saved only the areas of the image
that covered the seam, only these areas are
replaced. Repeat this process for any further
seams on your model and then save the new
fixed texture as a new image.

4. Next, copy this new merged layer and use it as

a mask for the fixed texture. Press ctrl -A to
select all and ctrl -C to copy the layer to the
clipboard.