Options tab

Contains infrequently used render settings, including settings for memory and performance, framebuffer settings, and various overrides.

Memory and Performance

Tile Scheme

Select from the following ways for Turtle to distribute tiles over the image plane:

Hilbert

A way for Turtle to achieve maximum coherence, the fastest rendering time possible.

Left to Right
Render from left to right.
Concentric
Starts in the middle and renders outward in a spiral.
Random

A good way to get an early feel for the whole picture without rendering everything.

Tile Size

A smaller tile gives better ray tracing coherence but more inefficient shading. There is no 'best setting' for all scenes.

Use one thread per CPU
When on, Turtle automatically detects the number of available processors.
Rendering Threads
Manually set the number of rendering threads.
Use SSE

Turtle uses specialized vector instructions to speed up the rendering. The cost is higher memory usage. Turn off SSE/AltiVec if Turtle starts swapping memory.

Use Instancing

Enables use of instanced geometry, which saves memory. If disabled all instanced shapes will get a separate copy of the geometry, which might decrease render time, but increases memory usage.

Vertex Merge Threshold

Sets the threshold used for merging multiple face vertices into single vertices when loading scene geometry. If the difference of vertices is smaller that this threshold they are merged. This is used to optimize meshes data and decrease memory usage. The default value 0.001 should rarely be altered. Can be set to 0.0 to disable mesh optimization.

Framebuffer

Premultiply Alpha

If this box is checked the alpha channel value is premultiplied into the color channel of the pixel.

Note: Disabling Premultiply Alpha gives poor results if used with environment maps and other non-constant camera backgrounds, but it can be convenient when compositing images in post.
Premultiply Threshold
This is the alpha threshold for pixels to be considered opaque enough to be 'unmultiplied' when using premultiply alpha.
Enable Input Gamma Correction

Turtle renders everything in linear intensity space (not gamma corrected). This means Turtle assumes that all colors selected as inputs on Maya shaders are treated as linear, the same applies to all file textures. The output image produced by Turtle is also in linear space. If this is not desired Gamma Correction can be automatically applied to the input colors and textures, and to the output image.

For example, if the file textures are in gamma 2.2 and the resulting image needs to be in gamma 2.0, setting input gamma to 2.2 transforms the input textures from 2.2 to 1.0 (linear space). Setting output gamma to 2.0 transforms the rendered image from gamma 1.0 (linear) to 2.0.

If some file textures are in linear space, input gamma correction can be individually disabled on the file texture nodes. HDRI file formats such as OpenEXR and Radiance HDR are always treated as linear.

Gamma correction, both input and output, applies to all render modes including Vertex Baking. The exception is Point Cloud Baking where the output file format is always considered linear, and will thus ignore any specified output gamma correction.

Gamma correction is designed to correct colors with intensities between 0.0 and 1.0 between different display devices. Maya lets you set color values with any possible brightness, but this leads to very unpredictable results as a relatively limited color value can still be boosted to huge values by the gamma correction. Try to keep colors limited, and use Intensity sliders where available, as scalar values are never gamma corrected. This ensures that the color you see on your monitor transfers correctly to linear color space, and still has the boost in intensity that you want.

Input Gamma Correction

Selects the gamma space that input colors are assumed to be in.

Note: HDRI images are always considered linear.
Output Correction
Select the type of correction to apply to output colors.
None
Writes the linear colors directly.
Gamma
Takes the linear colors to the gamma specified in Output Gamma Correction.
SRGB

Converts the colors to SRGB when showing them. This is similar, but not identical to gamma 2.2.

Output Gamma Correction
Only considered when Output Correction is set to Gamma. Selects the gamma space the rendered image is transformed to.
Dither Final Color
Turn on if you want images dithered during conversion from high dynamic range float to low dynamic range integer colors.

Output Shader

Output Shader

The image rendered can be post processed by applying an output shader. It can only operate on single pixels, one at a time and thus cannot do any advanced operations such as blurring or multi-pixel filtering. It is primarily used for gamma correction or color channel swapping. To use, apply a simple color utility to the shading box. When the shading network is finished, the node ilrOutputShaderBackendNode must be applied to tell the shading network where it should get its color information. A simple example of an output shader could be: Connect a gammaCorrectNode to the Output Shader in the Render Globals, connect a ilrOutputShaderBackendNode to the Value of the gammaCorrect, set up the gammaCorrectNode accordingly, and then render and enjoy your gamma corrected image.

Note: The ilrOutputShaderBackendNode must be assigned in the shading network, otherwise Turtle does not insert the original image color correctly. Failure to do so results in a black image.

Output Verbosity

Error

Prints error messages.

Warning

Prints warning messages.

Benchmark

Prints benchmark information.

Progress

Prints progress information.

Info

Prints info messages.

Verbose

Prints verbose information.

Debug

Prints debug information. Used for development purposes.

Save output to file

If enabled, all output is saved to the file <Maya LT project path>\Turtle\temp\debug.out.

Advanced Settings

Texture Cache

Enable Texture Cache

Selects whether the texture cache should be used or not. The texture cache works by storing textures in a format supporting random access making it possible to load them more efficiently. In scenes using large textures this will make the memory footprint of textures smaller and the texture loading faster. If disk space is an issue, the texture cache may be a problem since it stores copies of all textures.

Read Only Cache

If this box is checked, textures already in the cache will be used, but modified or added files won’t be cached.

Texture Tile Size

Sets the size of tiles in the textures. Smaller tiles will make the cache more memory efficient, but somewhat slower.

Texture Cache Size (Mb)

Sets the maximum memory usage for the texture cache. Note it’s the memory used by the renderer, not physically on the disk.

Minimum Texture Size (Mb)

Sets the minimum memory usage for a texture for it to be cached. It may be unnecessary to cache small textures that won’t use very much memory anyway.

Texture Compression Type

Sets what compression to use for textures stored on disk.

None
No compression, gives high performance and large disk usage.
RLE

Run Length Encoding. Gives good compression on images with large single colored areas.

PIZ
A good compression type if using large tiles.
ZIP
A versatile compression giving good results for texture maps in general.
Texture Cache Directory

Sets the directory in which the textures will be stored. A directory starting with “//” refers to a directory in the project path.

Delete Cache
Deletes all the files in the texture cache.

Advanced Raytracing Settings

Recursion Depth
Decides how deep the Ray Tracing Acceleration Data Structure can recurse.
Recursion Threshold

Decides how many triangles that can reside in a leaf before it is split up. The Recursion Depth has precedence over the threshold. A leaf at max depth will never be split. The Recursion Depth and Recursion Threshold are advanced settings that shouldn’t be altered unless Acceleration Data Structures are second nature to you.

Overrides

Ignore Light Links
When on, Turtle ignores light links. Use this option if you find there are issues with light links, which can occur in scenes with a lot of geometry and lights when no light links are available.
Enable Quality Limits

Soft ray traced shadows and glossy reflections tend to increase render times and generally need a lot of tuning to get a good result at a reasonable render time. Turning Enable Quality Limits on limits the number of rays for all light sources and glossy shaders in the scene, disregarding the actual values on the shaders. This is useful when rendering previews of scenes to see the overall look before starting the final render.

Max Shadow Rays

The Max Shadow Rays setting cannot be used to raise the number of shadow rays above the number set in the Shadow Rays setting for any light source, only to lower the limit. For example, if Max Shadow Rays is set to 60 and Shadow Rays for a light source is set to 30, there will not be more than 30 rays per point for that light source. If Max Shadow Rays is set to 15 and Shadow Rays is set to 30, no more than 15 rays will be sent.

Max Glossy Rays

Sets the number of glossy rays used to determine the influence of a light source at an

Min Shadow Rays

Use this value to ensure that you get enough quality in soft shadows at the price of render times. The setting sets a lower limit on the number of rays sent to determine whether a point is lit by a light source or not. This raises the minimum number of rays sent for any light sources that have a Min Shadow Rays setting lower than this value.

Note: This setting cannot be used to lower the number if Min Shadow Rays for the light source is set to a higher value. For example, if Min Shadow Rays for a light source is set to 10 and this setting is set to 5, there will be at least 10 rays sent, provided that the maximum limit of rays is not reached before that. Setting this to a value higher than Max Shadow Rays under Quality Limits or Shadow Rays for the light source will not send more rays than the minimum value of those two settings for that light source.

Tangent Space

Flip for odd UV winding direction

Forces Turtle to mirror tangent and binormal when UV has odd winding direction.

Vertex Level Orthogonalization

Orthogonalize tangent space basis vectors (tangent, binormal and normal) at every vertex.

Vertex Level Normalization

Normalize tangent space basis vectors (tangent, binormal and normal) at every vertex.

Intersection Level Orthogonalization

Orthogonalize tangent space basis vectors (tangent, binormal and normal) at every intersection point.

Intersection Level Normalization

Normalize tangent space basis vectors (tangent, binormal and normal) at every intersection point.

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