Understanding Rayshader’s render_highquality() Function

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In recent years, rayshader has become a popular tool for rendering high-quality images in R. Its ease of use and versatility have made it a favorite among data visualization professionals and researchers alike. However, like any complex software package, rayshader is not immune to issues with image quality. In this article, we’ll delve into the specifics of render_highquality() and explore ways to minimize or eliminate unwanted grey noise in your images.

Introduction to Grey Noise

Grey noise refers to a type of additive noise that has equal intensity at all frequencies. When rendered using rayshader’s render_highquality() function, grey noise can manifest as a uniform grey or dark grey background, often accompanied by subtle artifacts and texture distortions. This issue is particularly prevalent in images with deep shadows or complex geometries.

The Role of Samples

The samples argument in the render_highquality() function plays a crucial role in determining the level of noise present in an image. By default, this value is set to 128, which can lead to noticeable grey noise, especially when rendering high-contrast scenes with deep shadows.

Increasing the number of samples (e.g., setting it to 512) significantly reduces noise and improves overall image quality, at the expense of increased computation time. However, balancing these competing factors is essential to achieving optimal results.

Using Multiple Light Sources

One effective strategy for minimizing grey noise involves utilizing multiple light sources instead of relying on a single default direction. By doing so, you can control the orientation and intensity of light in your scene, which has a direct impact on the final image’s appearance.

When using two or more light sources, each light source will cast its own shadow, effectively reducing the uniformity of grey noise across the image. This approach is particularly useful for scenes with complex geometries or deep shadows, where a single light source may exacerbate the issue.

Sample Code and Best Practices

Here’s an example code snippet demonstrating how to use render_highquality() with multiple light sources:

# Render high-quality image using render_highquality()
library(rayshader)
library(rayrender)

volcano %>% 
  sphere_shade() %>% 
  plot_3d(volcano, zscale = 2)

# Set the number of samples to reduce noise (512 in this case)
render_highquality(clear = TRUE,
                   filename="p1_hq.png",
                   samples = 512,
                   lightdirection = c(60,150))

In this code snippet:

• We first define our scene using volcano and apply a sphere shade to it.
• Next, we use the render_highquality() function to generate the high-quality image. Here, we set:
  • samples = 512, which is higher than the default value of 128.
  • clear = TRUE, indicating that the background should be cleared before rendering.
  • filename="p1_hq.png", specifying the output file name for the high-quality image.

Additional Tips and Considerations

• Choosing Light Directions: Selecting appropriate light directions can significantly impact the final image’s appearance. Experiment with different values, such as c(60,150), to find a combination that works best for your scene.
• Balancing Noise Reduction and Computation Time: When adjusting the samples parameter, be mindful of the trade-off between reduced noise and increased computation time. Higher sample counts will generally result in higher-quality images but also increase rendering times.

Conclusion

In conclusion, grey noise is a common issue when using rayshader’s render_highquality() function to generate high-resolution images. By understanding the role of samples and employing strategies like using multiple light sources, you can minimize or eliminate unwanted grey noise in your images. Remember to balance noise reduction with computation time to achieve optimal results.

Further Exploration

For further exploration and practice, consider experimenting with different sample counts, light directions, and scene geometries to fine-tune your rayshader rendering workflow.

By following these best practices and exploring the various options available in rayshader, you can unlock high-quality images that showcase your data or artwork in the best possible light.

Last modified on 2024-03-23