Reflectivity and highlight settings

Turns on reflections for this material.

Reflect the current environment in Hardware rendering mode, as well as other objects in the scene in Ray Trace rendering mode.

Use a reflection map when you want your materials to reflect something other than the environment background. Control brightness using the Reflection brightness slider (must be adjusted for each environment).

A reflection map must be a panoramic image in the “vertical cross” format. The image file should have an aspect ratio of 3:4 and pixel dimensions that are a power of 2 (24 x 32, 384 x 512, etc.). The image can either be a regular image (JPG, PNG, BMP) or a High Dynamic Range image (HDR, EXR).

Various materials reflect differently depending on the angle you view them from; for example, looking directly at a flat surface might show little or no reflection, but viewing the surface at an oblique angle might clearly show reflections. This effect is also called Fresnel. Use the Reflectivity menu to determine if reflectivity varies by angle viewed.

• Is constant across the surface : The brightness of reflections is constant across the surface (the default). Adjust overall reflectivity by dragging the Overall reflectivity slider that appears. Full reflectivity is attained when you drag all the way to the right (1.000).
• Depends on the viewing angle : Reflections are stronger on areas of the surface viewed edge-on and weaker on areas of the surface viewed directly on. Adjust this effect using the reflectivity graph that appears.
  

  The mathematical function that relates the angle of view to the amount of reflection is called a "Fresnel function", and it is uses three parameters: Bias, Scale, and Power. The fourth parameter, Max, stops the amount of reflectivity from ever going above a certain number.

  The formula is: reflectivity = bias + (scale * (1.0 - cos(view angle))**power)). You can try typing in these values directly, or use the reflectivity graph to change the Fresnel function. As you change the curve on the graph, the look of the material updates in the view.

  Change the reflectivity by clicking and moving the handles. The left side of the graph shows how reflective the material is when viewed directly ("at center"). The right side shows you how reflective the material is when viewed on an oblique angle ("at edge").

  See Reflectivity examples.

Controls the size of shiny highlights or hotspots on the surface. (This value is sometimes called eccentricity.) This value affects directional light, as configured with the Environment Light slider in the Directional Light and Shadows window.

Modulates or scales the intensity of the specular highlight. (This value is also called specular rolloff.) In other words, it affects how much of the highlight spreads into darker areas. Like highlight size, this value affects directional light, as configured with the Environment Light slider in the Directional Light and Shadows window.

Use this drop-down box to control reflection tint. You can tint the reflection with the material color, with a custom color, or not at all. If you choose the custom color option, controls appear so you can select a color or an image map. See Color parameters

(Not available when the custom reflection type is selected.) Dims the reflection by removing light that is coming off of the reflective surface. Use this in parallel with the Overall reflectivity slider or reflectivity graph under Reflectivity. Suitable for surfaces such as aluminum or gold. For example, gold tends to strongly reflect other colors in the scene, which might not be desirable. You can reduce this effect by increasing reflection absorbency.

Turns on blur and enables the accompanying Surface rougness slider. Useful for simulating materials that are reflective or transparent but do not have a perfectly smooth surface, such as sandblasted glass or metal.

Examples of use:

• Take a highly reflective chrome surface and use blur to make it look like silver or aluminum.
• With beige leather, and bump enabled, turn down reflectivity and use blur to make the surface look less like plastic.
• With glass materials, add a bump map and use and use reflectivity blur to create a "frosted" look.
• With Gold, turn up reflectivitity and use blur to give it a realistic sheen.
• If you want a polished surface, turn down Surface roughness.
• If you want a glossy surface, reduce or turn off blur.
• On wood surfaces, to get a satiny finish, enable blur, add some surface roughness and a bit of reflectivity.