Open topic with navigation

Fog With ArchiCAD Object Medium

Instead of using the Environment as a medium you can create your Fog using an ArchiCAD Object. This way you have more control to customize the Fog by not only setting the Medium parameters but also adjusting the Fog Object by changing size and placement.

Figure 1: ArchiCAD Object used for fog.

The workflow is:

1) Load scene into ArchiCAD
2) Zoom out to see total scene and add a large ArchiCAD Cube or Slab to create the Fog Object.
3) Enlarge the cube or slab to cover your entire scene, except the camera. Camera must NOT be inside the Fog Object
4) Set OctaneRender for ArchiCAD plugin. Open Viewport, start rendering.
5) Change the material of the cube to something not used elsewhere in the scene (i.e. ‘Fog-cube’)
6) Get back to your Camera (cube should be blocking the view; the ArchiCAD camera has always to be outside of the Fog Object)
7) Match your Camera View cone and the Size of the Fog Cube to make sure the Fog covers your Camera scene. You can either set your camera view cone smaller (to give yourself some space for the volumetric Object) or make your Fog Object bigger.
8) If you change your scene objects or add new materials you need to update the plugin, Rendering Tab → Refresh.
9) In ArchiCAD, unselect and reselect the cube (the new material should now be in the plugin MaterialsA set of attributes or parameters that describe surface characteristics. Tab)
10) Change cube material to specular, reflection 0, index 1, smooth disabled, roughness 0, fake_shadows enabled, medium scattering (scattering 1, absorption 0, phase 0.5, scale 0.01).
11) Change kernel to Direct Lighting.
12) Play with the Medium settings, rotate camera and move sun until you get the effect you are looking for!

The medium setting used in the workflow is a good basic to start with. Depending on your scene you need to tweak the parameters. Increase the Density to get more effort. A setting of 1 will be like a thick mist!

IMPORTANT NOTE: If you set the scene scale (Configuration) to 1, the scattering scale of about 0.01 is used). But it is easier to scale the scene down (0.1), then you can more easily tune the scattering. Remember to adjust the ray epsilon if you scale the scene.

Notes:

• A cube shape seems to work better than a sphere as the volumetric geometry.
• No need to reverse the normals of the volumetric cube.
• Only works well the Direct Lighting kernel.
• The effort works better inside (where there are darker shadows) than out.
• If you are doing an interior scene, with sun coming thru the window - just have the cube placed from the window to the camera. Do not place the cube outside the window (that just dilutes the effect).

In most ArchiCAD scenes the Fog Object might be a very large cube or slab to cover the scene. In the next example the Fog Object is 500x200x150 meters. The Object is placed near to the camera (in red).

Figure 2: ArchiCAD scene with Camera outside Fog Object (Slab).

Figure 2: Parameters Of Fog Object and result .

Figure 3: Two results with different settings for Density and ScatteringDefines how fast light gets scattered when traveling through the medium. direction.

Open topic with navigation