Blenderseed's export settings

In this tutorial, we go over the options and settings exposed in the Blenderseed export panel, as well as the various other ways to alter how a Blender scene gets exported.

Table of contents:

1. Settings controlling what gets exported
   1.1. Scene
   1.2. Camera
   1.3. Non-renderable objects
   1.4. Write Meshes to Disk
2. Settings controlling how it gets exported
   2.1. Export Emitting Objects as Mesh Lights
   2.2. Point Lights Diameter
   2.3. Point Lights Energy Multiplier
   2.4. Light-Emitting Materials Energy Multiplier
   2.5. Specular Highlights Multiplier
   2.6. Recompute Vertex Normals
   2.7. Apply Modifiers
   2.8. Tessellation Quality
3. Settings controlling the rendering engine
   3.1. Lighting Engine
   3.2. Sample Count
   3.3. Enable Image Based Lighting

1. Settings controlling what gets exported

1.1. Scene

A Blender project may contain multiple scenes. The Scene drop-down list lets you select which of those scenes gets exported to the appleseed project.

In a future version, Blenderseed may allow exporting multiple Blender scenes into the same appleseed project.

1.2. Camera

Similarly, a Blender scene may contain multiple cameras. The Camera drop-down list lets you select which of those cameras get exported to the appleseed project.

As of version 1.1.0 alpha-7, appleseed only allows a single camera per project file. Both appleseed and Blenderseed will eventually support multiple cameras per project file.

1.3. Non-renderable objects

1.4. Write Meshes to Disk

This checkbox controls whether the mesh data of the scene should be written to disk during export. When checked, mesh data (the *.obj files) are written to disk alongside the scene (the camera, the lights, the materials, the object positions and orientations, etc.) When unchecked, only the scene is exported.

When exporting a Blender scene to appleseed, you'll want to continuously tweak the scene and the export settings until you're satisfied. This requires the export step to be as quick as possible. Unfortunately, writing mesh data is a slow process. By checking 'Write Meshes to Disk' for the first export only and unchecking it for subsequent exports, you can speed up considerably the "export & render" cycle for large scenes.

Of course, this only works if the mesh objects haven't changed since the last export.

2. Settings controlling how it gets exported

2.1. Export Emitting Objects as Mesh Lights

This checkbox controls whether objects using a material with an 'Emit' value greater than zero should be exported as mesh lights.

Blender materials have an 'Emit' property that controls the amount of light materials emit. By checking 'Export Emitting Objects as Mesh Lights', you'll effectively turn all objects with a light-emitting materials into mesh lights.

Having a lot of mesh lights in a scene may increase the convergence time (the time required for the noise to disappear completely), thus it may sometimes be desirable to only export a few key objects as mesh lights. This is achieved as follow:

1. In Blender, select the object you want to turn into a mesh light, and open the Properties editor.
2. Go to the Material tab, and open the Custom Properties section at the bottom.
3. Click on the Add button to add a new property.
4. Click the Edit button of the newly added property, type 'appleseed_arealight' (without the quotes) in the Property Name input. The value of the property is not important.
5. Click OK.

At this point, it should look like this:

Repeat the steps above to tag all the materials that should emit light in the appleseed render.

Now, when exporting the scene to appleseed, uncheck 'Export Emitting Objects as Mesh Lights' to make sure only those objects with tagged materials actually emit light.

Notes:

• The custom property 'appleseed_arealight' is set on a material, not on an object. This implies that all objects using a material with 'appleseed_arealight' will be emitting light.
• Materials with 'appleseed_arealight' will be exported as light-emitting materials regardless of the value of the Emit property.
• If the Emit property of a material with 'appleseed_arealight' is set to 0, it will be exported as if it was set to 1.

2.2. Point Lights Diameter

As of version 1.1.0 alpha-7, appleseed only supports mesh lights. Since point lights are not yet supported, Blenderseed exports them as small invisible spherical lights. This option allows to control the diameter of those point lights.

2.3. Point Lights Energy Multiplier

This option allows to control the amount of light that should be emitted from point lights.

2.4. Light-Emitting Materials Energy Multiplier

This option allows to control the amount of light that should be emitted from light-emitting materials.

2.5. Specular Highlights Multiplier

This option allows to control the strength of the specular highlights.

2.6. Recompute Vertex Normals

When checked, Blender will recompute the vertex normals of mesh objects before writing them to disk. When unchecked, vertex normals will be exported as they are.

2.7. Apply Modifiers

This option allows to enable or disable modifiers on mesh objects.

2.8. Tessellation Quality

This option allows to control the quality of the tessellation for non-polygonal objects.

As of version 1.1.0 alpha-7, appleseed only supports polygonal geometry: higher order surfaces (NURBS, subdivision surfaces, free form surfaces, etc.) are not yet supported. When exporting a non-polygonal surface from Blender to appleseed, Blenderseed will first convert it to polygonal geometry (it will "tessellate" the surface into triangles). The 'Tessellation Quality' option allows to control the "fineness" of the tessellation (the number of triangles):

• In Preview mode, fewer triangles will be used to approximate a given surface, potentially resulting in a faceted look but reducing the export time, the render time and the amount of memory used during rendering.
• In Render mode, more triangles will be used, producing a smoother surface but increasing render time and memory usage.

Note that the actual settings for the Preview and Render modes can be modified in Blender. Typically, the Preview mode uses lower tessellation settings than the Render mode, but this is not required and is not necessarily the case.

3. Settings controlling the rendering engine

3.1. Lighting Engine

The 'Lighting Engine' drop-down list lets you select the rendering engine to use in appleseed. As of version 1.1.0 alpha-7, two of appleseed's rendering engines are exposed:

• The Distributed Ray Tracing engine computes direct illumination only:
  
• The Path Tracing engine computes full global illumination:
  

3.2. Sample Count

appleseed provides two rendering modes:

• The progressive rendering mode continuously refines the whole image, and must be manually stopped when the desired rendering quality has been reached. This mode is well suited for interactive rendering, quick previews, or when one wants to let the rendering engine improve the image until the time budget is reached.
• The final frame rendering mode computes the image one tile at a time using a predetermined number of samples per pixels. This mode is more efficient than the progressive rendering mode, but one needs to know in advance how many samples per pixels are sufficient to fully eliminate the noise.

The 'Sample Count' setting lets you choose the number of samples per pixels for the final frame rendering mode.

Note that appleseed lets you choose which rendering mode to use, you don't have to do this choice at the time you export the scene from Blender.

3.3. Enable Image Based Lighting

(This setting will be available starting with Blenderseed 1.1.1 which will be released together with appleseed 1.1.0 alpha-8.)

This checkbox allows to enable or disable image based lighting, that is, illumination coming from the environment.

In the following render, we set the world's horizon color to light blue, selected the Path Tracing lighting engine and checked 'Enable Image Based Lighting':

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