Scattering Megascans Atlases with Forest Pack
My name is Darryl Johnson and I am an Artist and Pipeline Manager for Quixel’s Megascans. I come from an automotive background working on car commercials as a 3D generalist. I have worked at Blur Studios as a scene assembler, and at Blizzard as a lighter/compositor on the recent Overwatch cinematics. In this tutorial, I want to go over my process for using Megascans atlases with iToo’s Forest Pack for my Quarry pack eye candy scene.
Importing Atlases using Bridge
Importing atlases is a little bit different from importing assets, but not by much. The only difference is, instead of geometry being imported, it is the material that is imported into 3ds Max and loaded into the material editor.
- The new imported material will appear in your material editor.
- Before cutting out our cards or billboards, we need to make a square plane and apply material. I like to start off with a plane with 20×20 segments.
- After that, apply an “Edit Poly” to the plane.
Cutting out Atlases
This section can be done in many different ways; I personally prefer to cut out my atlases by tracing the individual pieces using the opacity map, visible in viewport and with the cut tool in vertex mode. Note, I am using “Compact Material Editor”.
- Apply the loaded material to the plane.
- Inside the material, scroll down to the “Maps” rollout and open the Opacity map.
- While the opacity is loaded, click the “Show Shaded Material in Viewport” on the “Material Editor Toolbar.”
- With the plane selected, switch to “Vertex” mode and enable the cut tool.
- With the cut tool enabled, cut an outline of the individual assets in your atlas maps (leave some padding for the opacity map). Don’t be too concerned about how clean the cuts are because we will be changing the topology later.
- After this is done, select the faces of your individual atlas and “Detach.”
- To achieve a clean flow of polygons on my card I added a “Subdivide” modifier to the edit poly. I then adjust the “Size” in the parameters until the polygons are distributed evenly across the mesh. Depending on whether the card is going to be bent or standing up right, will determine whether this will be high or low poly.
- After all the cards are cut out, make sure the cards are oriented in the correct direction it will be scattered. Forest Pack will use the pivot and direction to scatter the card.
- To do this click on the “Hierarchy” in Command Panel and select “Affect Pivot Only”. With this selected, you can move the pivot into position. *Remember to disable “Affect Pivot Only,” when done.*
Making Redshift Shader
Because I am using Redshift, I prefer to use the “Redshift Sprite” material. This handles my opacity maps inside the Redshift renderer.
- Since my material is already loaded in the material editor, all we need to do is change the “Redshift Material” to a “Redshift Sprite”. When prompted about “Replace Material,” select “Keep old material as sub-material.” This way the shader that is already built by bridge will drive the “Redshift Sprite” material.
- Under “Stencil” load the opacity map from the atlas here. This will stencil out any excess geometry that is in your card.
- Go into the “Input Material” and disable or clear out the opacity map because “Redshift Sprite” stencil will be doing all the work.
- From here, you can do some test renders to make sure the stencil and the shader are working correctly.
Customizing the foliage with multiple variations is going to create a more unique composition when using Forest Pack to scatter. While this can be tedious work, the mileage you can get out of this process can be invaluable. After you are done setting up your atlases, I would highly recommend saving these out for future projects
- For this step, I would make around 3-5 variants of each card.
- With my variations I used a combination of bends and old school poly modeling to achieve different looks. If you find you don’t have enough geometry to bend or customize your card, you can add another “Subdivide” to get more geometry.
- Also make sure you name your atlases and variation in a way it is easy to organize.
Setting up Forest Pack
There are multiple methods for setting up Forest Pack. Some people like to use splines or maps to drive their systems. For this particular system, I chose to custom paint method. Forest Pack has the option to use a paint brush inside your viewport and paint where your would like your scattered objects to be placed. This was very useful for me because I had a static camera.
- Switch from “Standard Primitive” to “Itoo Software” under the Create Panel.
- Select “Forest Pro” then select the surface you would like to scatter and immediately change to the “Modify” tab to avoid creating multiple Forest Packs.
- A “default” card will be loaded for representation of Forest Pack. This can be deleted after you load up your first atlas geo. This can be done by using either of two methods:
- 1) Click “Add new item” and change the template to “Custom Object.” After this, select the geo in your scene.
- 2) Click “Add multiple Custom Objects” and select from a list of geo in the scene.
- After my geo is loaded, I immediately change or check these settings under the following rollouts:
- [Geometry] I uncheck “Consolidate Material” because I sometimes make custom shaders and would like to instance them across multiple Forest Pack systems.
- [Surface] I double check that I am scattering across the correct surface or add additional surfaces.
- [Transform] Check “Rotation” and “Scale” to add variation. (Enabling Horizontal Mirror can add additional variation)
- [Display] Change viewport to “Points-Cloud.” (This will allow me to view my scatter as a point cloud instead of loading each mesh as geo which can slow your viewport down if you are working with a big scene.)
Customizing Forest Pack
Now that I have my geo loaded and all my default setting set up, I can begin to scatter and customize my system’s look (I will do test renders throughout this process to get a better visualization).
- If I find that my atlas geo is too small, I can change the scale globally or individually without editing the original geo under the “Geometry” rollout.
- Under the “Distribution Map” rollout, I will sometimes use one of the preloaded maps to drive my scatter. By default the density of the system will be very sparse. One way to adjust this is to change the value of the unit size under “Density” while still in the “Distribution” rollout. This can be adjusted throughout the project to get the desired look.
- I found that painting in my grass was the best option due to the static camera in my scene. This allowed me to have more artistic control over where I wanted my grass to be scattered. Again, there are multiple ways to drive where you place your system. So I advise you to look into what best fits your situation. The “Paint Area” tool can be found under the “Area” rollout
- By default, “Surface Area” will be on. This cannot be deleted, but it can be turned off.
- After “Surface Area” is turned off, I click “Add a new Paint Area.” When added, you will have a few new options in the properties:
- [Paint] Will turn your cursor into a paintbrush to paint in custom Forest Pack.
- [Erase] Will change your paintbrush into an eraser to remove already painted areas.
- [Brush Options] You can adjust the brush size and falloff in this menu.
- [Convert to Spline] This will convert the painted area into a spline (this works well when I want to use the same painted area in a different system).
- When I feel like I have a high enough density, I do some test renders to find out which of my atlases stand out more than the others. This happens because some of my variations are so unique they stick out like a sore thumb. To cull them, I will change their “Probability” under the “Geometry” rollout to a smaller value, like 1-5%. This will make that atlas feel unique in the scene without giving the scene a sense of repeating geometry.
- When this is complete, I will tweak the settings under the “Transform” rollout.
- [Rotation] I will change the “Min/Max” on the “X” axis, so the atlases are facing different directions.
- [Scale] I will change the “Min/Max” to get more scale variation. –
- [Mirroring] This will give me an extra amount of variation by mirroring some of the geo horizontally across the axis (this works well in high density systems).
At this point, I paint in the areas where I want to see a specific Forest Pack system. I want to note that you can add multiple “Paint Areas” to a single system. This step can take a while to get the look you want out of Forest Pack. Just to put it in perspective, I had almost 30 Forest Pack systems in my scene. Just like making variations to my atlas geo, I also do the same with my Forest Pack systems. For example, I sometimes change the color of my shader to appear dead or a lighter color. I also make systems just for a specific species of plant because that’s how it grows.
When it comes to fine tuning the Forest Pack for final, it can take some time to achieve. This is when artistry and problem solving comes into play. I say this because if you want to pull off a certain look whether it’s from reference or your own ideas, Forest Pack is a tool with dozens of ways to achieve your look. With that said, I would like you to take what I have done with my scene and add new tricks of your own. I am always finding new ways to use Forest Pack, and it’s pretty exciting when I do. I hope you enjoyed this tutorial and thanks for reading!