Soulburn Studios Art Lessons

Blended Cube Projection In 3dsmax
By Neil Blevins
Created On: Feb 12th 2013
Updated On: Dec 9th 2024
Software: 3dsmax

First off, I recommend reading my Blended Box Mapping tutorial first, it contains useful background info that will help you with this tutorial.

What is a Blended Cube Projection?

Say you have a complex object, like a robot head made up of 291 objects, and you want to paint some specific dirt on it, like dirt near the places where the screws intersect with the face shields, drips traveling down the face, darkening near panel lines, etc. Some possibilities...

You could uv the objects and then use a 3d paint program, but damn, uv mapping 291 objects is a real pain.
You could auto map it, but the result will be useless if you want to edit the textures in photoshop.
You could use Ptex, but then you'll have to keep track of 291 Ptex files associated with this model.
You could use procedurals, but it might be a lot of work getting it to look natural when it would be pretty easy to paint.
The Blended Box Mapping technique works great for applying "General" dirt to a surface, but you want control over placing the dirt in very specific spots.

If you want to apply "Specific" dirt to a surface, you need to take the next step, a Blended Cube Projection. This is very similar to a Blended Box Map, except instead of using a single map aplied to all 6 sides, you create 6 different maps, one for each direction, and then apply them to your surface.

The basic procedure is as follows, start with your model...

Assign a Blended Cube Projection.

Render Templates of your objects from all 6 sides.

Now open Photoshop, and load the front image. Create a new layer, and start painting a dark brown color everywhere you want dirt.

Save this as a psd file, so you can always go back to your working file.

Once done, click "Lock Transparent Pixels" in your layers palette on your dirt layer, and then fill your layer with white. Now everywhere you painted brown will be white. Then place a black layer below the dirt layer. And flatten the image. Now you have a black and white mask, where white will put dirt, and black will be transparent. Save this mask as a tif.

Open up max again, go to your Blended Cube Projection map, drop the dirt bitmap you just created in the front slot.

Now place your Blended Cube Projection map in the mask slot of a Blend material, with Material 1 being your metal material, and Material 2 being a dirt material.

Hit render, and voila, your dirt details are now projected on the front surfaces of your objects.

Repeat for the other 5 sides, and now you've placed specific texture details on all of your objects quickly and efficiently without the need to unwrap everything.

3dsmax BlendedBoxMap Example

The best and most modern Blended Cube Projection technique is using the BlendedBoxMap inside 3dsmax that was released in version 2017 Ext 1. If you turn it from using 1 or 3 projections to 6, you are now using it as a Blended Cube Projection instead of a Blended Box Map.

Here's a video showing the process...

3dsmax SoulburnScripts Blended Cube Projection Example

This is an older technique that I don't recommend using anymore, but I've included it here for historical purposes.

Take the robot head model with the simple metal material applied to it. Select all of the objects.

Now run my BlendedCubeProjectionMaker script, available here: Soulburn Scripts for 3dsMax page. Here's an interface snapshot...

Now make sure all 6 maps are empty (since we haven't painted the maps yet), and hit Do. Now we have 6 cameras pointing at our object from all 6 cardinal directions, Up, Down, Left, Right, Front, Back.

And we'll have 6 Planar UV modifiers aligned with the cameras.

We also have a mix map in the medit that uses all our cameras...

Next, we use another soulburn script, this one is called cameraMapTemplateRenderer. Here's the interface...

Change the Mode in the cameraMapTemplateRenderer to Selected Cameras, and select your 6 cameras. Next, it's recommended you turn on camera lights, so you get even illumination from all camera angles. Or for even better results, turn off all lights except a dome light (for example, use vray's "GI Environment" light set to a multiplier of 1 and a color of white in the render dialog if you're using vray as your renderer). Finally, in the script's interface, choose an output directory and hit Do. You'll now have 6 templates saved to you directory.

Now open Photoshop, and load the front image, and create the dirt layer are discussed in the section "What is a Blended Cube Projection".

Open up max again, go to the map tree that the BlendedCubeProjectionMaker script created, and load your new front bitmap in the appropriate map.

Now place your map tree in the mask slot of a Blend material, with Material 1 being your metal material, and Material 2 being a dirt material (this doesn't have to be complex, a standard material with no specular and a dark brown color for instance).

Now hit render. And voila, you have painted dirt on your model. Do the same for the other 5 directions.

Here's a video showing me apply a blended cube projection using the SoulburnScripts UVWMapping Technique to a robot head...

Conclusion

So the big advantages of using a Blended Cube Projection instead of unwrapping / ptex / procedurals are...

You were able to apply dirt to a whole bunch of objects without the need to worry about unwrapping the UVs on every object.
If you need to move or add to or modify the faces on any of your objects, you can do so without messing up your paint or uvs.
You have 6 images to manage, as opposed to possibly hundreds of images necessary for an unwrapped object.

Frequently I'll start by making a material that uses a Blended Box Map, just to get the basic patterns on the object, then I'll use a Blended Cube Projection to add more specific details on top. For those of you who do Matte Painting, you'll recognize this technique, it's just it's being used to do regular shading as opposed to being used to do more traditional Matte Painting from the hero camera.

Anyways, hope you see the advantages of the Blended Cube Projection technique and give it a shot. You may never unwrap the UVs on another object again!