Wednesday, 29 October 2014

Jack'O Lanterns

Can you feel it? It's Halloween and is coming! Today I am feeling in the mood to write a themed post on pumpkin carving...but in 3D of course.

So,first off we will need to do a pumpkin model. The good thing about pumpkins is that are pretty easy to model and even if the shape is not perfect, it won't really matter since in reality pumpkins have many shapes. Don't forget to make the small stem on the top.

Pumpkin modelling in Maya
Pumpkins are just deformed spheres
Because we are working on a very organic 3d piece, I decided to do some workaround on a high res version on Zbrush. Once again, you are free to deform your pumpkin to your liking. There are no written rules on how a pumpkin must be.

Pumpkin in Zbrush
My pumpkin after some Zrbrushing. 
After sculpting on Zbrush, you should review the low poly version in Maya and make it its UVs. If you messed the topology with Dynamesh, then you will probably have to do some retopo.
So, now we should be ready to bake our normal map. Nothing weird, I did this on xNormal.
Then as usually, I tweaked my texture on Photoshop.

Pumpkin Normal map

Because the carvings I'll be doing in this pumpkin are going to be pretty detailed, I decided to do it through texture. You can actually carve the geometry of the mesh using booleans or the split polygon tool in Maya if the carved faced is pretty basic but I wouldn't do it at all if you are planing something complex.

Anyway, I picked 3 random jack'o lanterns images from Google and made 3 masks out of them in Photoshop which, as usually, were merged on a single texture. Place them so they match your UVs.

Pumpkin mask texture

For the color texture I did something pretty basic. I'm not very good at drawing and painting after all. I did however, include the AO bake on the alpha channel for material shading purposes.

Pumpkin color texture

Having finished theses 3 textures and my low poly model, I just imported them on Unreal and worked on my magic material. This is how it looks my network.

Pumpkin material network

Pumpkins do have some light transmission effect just like wax or human flesh, so I decided to make use of the Subsurface Effect (although I didn't test the new subsuface profile option in 4.5).
Also yoy may notice I made use of the NormalFromHeightmap node to do the matching relief for the carving which saved me from making 3 different texture for my normals.
This is the result.

Pumpkin in the dark 1

Pumpkin in the dark 2

Needless to say that jack'o lanterns are meant do be used in the dark and in conjunction of point lights.

And there is also another option involving the use of a masked material and a two sided material. As you see in image below, the shadow cast by the inner light is pretty awesome and can achieve some cool effect, though have in mind that the inside of the mesh will be visible and a physical light source as a candle should be added. For this one, I decided the SSS was counter-productive

Pumpkin masked material

And this is the network for the masked material. Be sure that you checked the "two sided" option or you won't see the inside of your pumpkin!

Pumpkin masked material network

And this is it. Have a creepy Halloween!


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