Friday, 17 January 2014

A simple trick to reuse parts of a normal map

Have you ever wanted to reuse parts of a normal map only to realise the copied part doesn't render as expected?
This is because normal maps take the direction of the normals, reduces them to colours and applies them to a 2D texture. If you simply copy a piece of detail and flip it to fit your UVs, while your detail will fine, the colours have been untouched and therefore the normals are still pointing where they were before.

This leads to problems and is why the render doesn't look correct. The details were flipped but not the normals!
This is what I will explain how to counter with an extremely simple trick.

The thing to understand is each colour channel points in a different direction. Depending on the engine, the directions will be different. In the case of Blender, RED is X, GREEN is Y and BLUE is Z

 Here is an example. I want to copy a piece of detail to another area of the normal map.

The first step is to copy and flip the piece of detail.

As you can see, the detail is flipped but the normals are not since the colours haven't been touched.

The next step is done in an editing software. Any software that can edit RGB channels independently will work. Select the new piece of detail and go into a channel editing window.

From the screenshot above you can see that we need to flip the RED channel because we flipped the detail along the X axis (to the right). The GREEN channel does not need to be flipped because the Y component of the normals is already correct since we only flipped the image in the X direction.

So this is what we do. We select the area we mirrored, go into channels window and invert the colours. Dark things will become lighter and vice versa meaning the direction of that component of the normal will be reversed. So instead of pointing where it was before, it'll point in the way we want.

Here is the result. You can see how the lighting now matches meaning the two are now pretty much identical, but oriented differently. Now lighting will behave as expected.

I hope this was helpful!

Saturday, 11 January 2014

The Homerun Slicer: Dota2 Item

After a lot of frustration with the weapon being at 90 degrees from the expected orientation and realising I made a silly mistake we finally finished it!

The model and concept were inspired by a Digital Tutors tutorial, and made by Kejayarts ( while I produced the textures.

It was entirely painted in Blender.

Meepo weapon texture

View of the text on the weapon

Meepo weapon side view

Thursday, 9 January 2014

Tesla S turntable

I recently made quick a turntable of the Tesla S. I wanted to play with cycles and materials so this was perfect. I still need to work out how reduce the apparent noise in the image without increasing render time too much.

More work needed to fully complete the model. Mostly in the tail lights as well as various other areas of the body which I want to be closer to the real Model S.

I made good use of the RayPump service to render it in under 10 minutes.

Tuesday, 7 January 2014

Dota2 Raccoon Courier

This is the culmination of months of on/off work. The process was similar to my last character. The main difference this time, was that the rigging and animating was offloaded to an animator friend of mine.

Also, notice the DIY Hero shader made with BI nodes. I tried to replicate the in-game shader. It's not quite there, for one there's no normal map, or most of the other maps used by the real Hero shader, but I think it's a start.

The texture still needs a bit of work but it's almost there.

Dota2 Weapon Model

My friend asked me to produce the texture for his first Dota2 item. Naturally I accepted. 

I decided I would use the Blender painting tools exclusively as I wanted to try out a new workflow.

With a Wacom tablet, Blender's texture painting tools are simple and surprisingly fun to use. The following pictures are work in progress.