PHOTOREAL LANDSCAPES

Germán Casado Fraga reveals how to harness a professional workflow to create a detailed landscape for VFX

Germán Casado Fraga reveals how to create a detailed landscape using Clarisse

c larisse is a very powerful application and a godsend for CG environment artists. In this tutorial, we’ll have a look at some of its features.

The workspace layout is fully customisable, so I first make sure it shows what I’ll be needing. I also create a project structure to keep my items organised.

The scene organisation works very much like a regular file navigator and it’s very intuitive. Folders are called ‘contexts’; contexts can be created, duplicated, and more importantly, referenced in other contexts. Once you get used to working this way, it’s hard to go back!

I’ll take you through the steps to create a simple landscape scene. I’ll be using imagery from Utah’s State Geographic Information Database (SGID) – they have a great portal where you can download digital elevation images, LIDAR and orthophotography (www.raster.utah.gov).

In the online Vault, you can find high-resolution screen grabs to follow my settings and download the texture files used in this scene.

01 Getting started

Create a map file item by right-clicking through the contexts: New>texture>map>map File. All items can be created by rightclicking in the browser window and navigating to the relevant section. I set the projection mode to Planar Y, and set the path to my texture. Now I create a polygrid in the Geometry context and set its size; in this case each pixel of my elevation map equals 0.5m, so I make the polygrid 4,651 km by 3,6455 km, and set its divisions to 250.

I can now go back to my Map File node and click on Fit to Bounding Box (make sure your Y value is 1). My texture is aligned to my grid, so I can duplicate it and set its path to my colour texture.

02 handling materials

I create a material for my geometry in my Materials context and lock the Attribute Editor by clicking on the lock icon. This allows me to navigate to where my textures are and drag them to the corresponding slot in the material properties.

To see the geometry, I drag the Geometry folder to the Display Selection Mode drop-down in the 3D view. This is a very common workflow in Clarisse. The 3D view can be very easily configured to only show contexts, geometry groups, objects and more.

It’s now that the texture loads into memory: Clarisse only loads data when it’s needed.

03 Assigning the Displacement texture

To add the displacement, you need a displacement item. Displacement, clip maps and materials are shown on the Material Linker (in the far right panel under Attributor Editor).

After assigning my displacement texture, I make sure that the Single Channel Behaviour in the Attribute Editor is set to Force Luminance.

The polygrid has been displaced upwards. I know the lowest value of my displacement map, so I move my geometry in the Y axis by that amount so it’s in line with the ground plane.

04 trillions of polygons

In the 3D view, I change the Refresh Mode to FPS Driven. This ensures that I’ll have smooth interactivity no matter how many polygons are in the scene – Clarisse’s viewport doesn’t rely on

Opengl, so you can easily navigate scenes with trillions of polygons! Then I create a Perspective Advanced camera in my camera context, and drag it to the eye icon in the 3D view to look through it and compose the shot.

05 using 3D layers

Selecting the Image item, I can see in the Layer editor that there is a layer called background. Every image can contain multiple layers, these are 3D layers – referring to objects in the scene, textures or even other images within my scene. In this case, I just need a 3D layer. So I create a new Path Tracing item in the Shading context and assign it as the renderer by dragging it to the Renderer slot, and I do the same with my camera.

The Anti Aliasing Sample Count can be increased to 12 samples per pixel, and I change the Anti Aliasing filter to a Blackman-harris filter.

06 lighting the scene

I now need some light, so I click on the chrome ball icon in the Lighting tab and pick an HDRI.

The image is still black. The 3D layer in my image has all its visibility options set to Use Current Context. You can define geometry groups, but in this case I’ll just instance the contexts that I want the renderer to see. This can be easily done by right-clicking and dragging whatever context you want the renderer to see into the Image context. I bring in my Geometry context and my Lighting context.

The Geometry and Lighting contexts are now instanced inside of the Image context and their icons have changed to reflect whether they are a source (S) or an instance (I). Assets can be organised in their own contexts and referenced in other contexts or across scenes.

You could, for example, create a lookdev context that would have its own image. You would just need to instance in it your lighting and whatever asset you wanted to lookdev.

To see my HDRI in the scene, I create a new sphere geometry, make it very large, assign a Matte material to it and point it to the HDRI texture. In the Attribute Window all the visibility options except for Unseen by Renderer and Unseen by Camera should be ticked. Cast Shadows, Receive Shadows and Is Emitter should be turned off. We also have to change the original texture mapping type from Parametric, to Spherical Y.

07 work on the Foreground

I want to add some detail to the foreground of the scene. Since my displacement is being applied as a planar projection, I can align a plane to my foreground and export it for detailing.

To bake out displacement, it needs to be applied as a deformer, since the displacement I applied previously is calculated on the fly.

To line up my new plane to our foreground, I just need to select it and move it while pressing the [S] key. It will snap to the vertex under the mouse.

Once lined up, and checking that it covers enough area, I add a Displacement deformer in the Deformers drop-down menu, making sure I turn Local Deformation off. Copy the terrain’s Y value, and they should line up perfectly. You can export it to an external app for editing through the File>export menu.

After importing the terrain back, I can work on my external app, updating the file and pressing Ctrl+r in Clarisse to reload any changed assets.

To add some rocks to the foreground, I import some external .obj files into my Geometry context. I create a Point Cloud item in my Scatterers context and set my newly imported foreground object as its source in Geometry under the Scattering options. Starting with a Density of 1.

08 using the scatterer

The Scatterer is a really powerful scene tool that enables you to scatter tons of scene objects. I set my point cloud as the Geometry Support, and under Geometry I choose my rocks.

I adjust the Scatter Scale, Scatter Scale Variance and set Scatter Rotation Variance to 360 on all axes. To create a second layer of detail, I duplicate and rename both my scatterer and point cloud, and change their settings to make pebbles: 303,811 geometries, 5.568 billion polygons and no lag at all!

09 scatter some points

Let’s scatter some points on the main terrain. I create a new point_uv_sampler in my Scattering context. A regular Point Cloud item would also do, but the point_ uv_sampler looks at values in the chosen texture to place the points, while the point cloud places them and then culls them by looking at the texture, so it’s not as efficient.

10 Adjusting particles

I can see that my particles are not sitting on the ground. I move my terrain from its original position and parent my point cloud so that the transformations carry along. In the Attribute Editor, I choose a terrain as Parent in the Parent slot – right under the transform controls – and I set the Y translate to zero again. My particles are now on the terrain.

11 Decimate with textures

You can control which points you decimate with a texture. I duplicate my colour texture, set its mapping to UV and set it as Texture in the point_uv_sampler. Some points may disappear. If you bring up the Material Editor and select my point_uv_sampler, you’ll see it’s wired to your texture. Now press [Tab] and add a Remap node. Adjust the curve to improve the scattering.

12 ADDING variation

The Instance Color node can be used to easily add variation. Here, we can see how the texture maps on the foreground terrain and how it maps on the scatterers. You can duplicate and offset the texture, and blend between them to add even more variation and avoid tiling. I import my bushes into my ‘geometry’ folder and use the same procedure as with the rocks.

13 Detail the Foreground

After tweaking the shaders and distribution, I want to add some more detail to the foreground. The Clone Stamp 3D tool is ideal for this process. Select which objects you want to ‘paint’, and set the randomness you want. A target geometry can also be specified. In this case, I pick my foreground floor and add some more rocks.

14 ADDING Atmosphere

To add atmosphere, I add a Geometry Box Volume, set its size to encompass my scene and assign a volume material to it. I usually start with a 0.001 density in the volume box and then adjust my material settings, tinting the scattering blue, and adding red to the absorption colour.

15 render the Final scene

You can do most material and lighting tweaking in the 3D view, but if you need to look at your image, there is a handy slider that will reduce the quality of the render settings. So you can leave your Pathtracer item untouched and just adjust the slider to get faster feedback. I now just need to render my image, replace the sky and do some comp work on it.