Blended Cube Projection
By Neil Blevins
Created On: Feb 12th 2013
Updated On: Nov 19th 2016

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, 291 objects to be exact, 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...
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, 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.



There are three different ways to make a Blended Cube Projection...
All have advantages and disadvantages.

Max 2017 Ext 1 BlendedBoxMap Technique

The best and most modern Blended Cube Projection technique is using the BlendedBoxMap inside Max 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...



This technique is full of advantages, the only real disadvantage to this technique is it requires max 2017 Ext 1 or higher to work. So if you're using an older copy of max, you may want to try out the other two techniques below...

CameraMapGemini Technique

This technique uses the free plugin CameraMapGemini to project your textures onto the surface (make sure you have the free plugin CameraMapGemini v0.16 or higher by Markus Boos http://www.projectgemini.net/CameraMapGemini/). 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), choose CameraMapGemini Method in the Create Mapping Modifiers dropdown, and hit Do. Now we have 6 cameras pointing at our object from all 6 cardinal directions, Up, Down, Left, Right, Front, Back.



And a CameraMapGemini modifier is assigned to the objects...



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...



First, change the Mode to CameraMapGemini. 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 CameraMapGemini Technique to a robot head...



UVWMapping Technique

This technique is almost identical to the CameraMapGemini technique, except it uses Planar UV modifiers instead of camera projections. Here's the differences in the setup:

When using the blendedCubeProjectionMaker, set it to UVWMapping Method in the Create Mapping Modifiers dropdown. 6 Cameras will again be created, but instead of a CameraMapGemini modifier assigned to our objects, we'll have 6 Planar UV modifiers aligned with the cameras.



Change the Mode in cameraMapTemplateRenderer to Selected Cameras, and select your 6 cameras. It will render the 6 templates exactly like before.

Paint your maps exactly like before, and place them in the same slots. The visual result will be identical.

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



Comparing The CameraMapGemini and UVWMapping Methods

The main advantages of using the UVWMapping Technique over the CameraMapGemini technique are...
The main disadvantages of using the UVWMapping Technique over the CameraMapGemini technique are...

Conclusion

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


This site is ©2016 by Neil Blevins, All rights are reserved.
Back to NeilBlevins.com